CN117413514A - Video codec using overlapped block motion compensation, combined inter-frame intra prediction and/or luma mapping and chroma scaling - Google Patents
Video codec using overlapped block motion compensation, combined inter-frame intra prediction and/or luma mapping and chroma scaling Download PDFInfo
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Abstract
An example apparatus for decoding video data includes one or more processors implemented in circuitry and configured to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block. To generate the final prediction block, the processor may perform LMCS on the first inter-prediction sub-block, combine the LMCS mapped first inter-prediction sub-block with the intra-prediction block using CIIP, and perform OBMC between the first CIIP prediction block and the second inter-prediction sub-block.
Description
Cross Reference to Related Applications
The present application claims priority from U.S. patent application Ser. No. 17/662,140, filed 5/2022, and U.S. provisional application Ser. No. 63/197,190, filed 4/6/2021, which are incorporated herein by reference in their entireties. U.S. patent application Ser. No. 17/662,140, filed 5 at 2022, claims the benefit of U.S. provisional application Ser. No. 63/197,190, filed 4 at 2021, 6.
Technical Field
The present disclosure relates to video coding (codes), including video coding (encodings) and video decoding (decoders).
Background
Digital video capabilities can be incorporated into a wide range of devices including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal Digital Assistants (PDAs), laptop or desktop computers, tablet computers, electronic book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video gaming consoles, cellular or satellite radio telephones, so-called "smartphones", video teleconferencing devices, video streaming devices, and the like. Digital Video devices implement Video codec techniques such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, section 10, advanced Video Codec (AVC), ITU-T H.265/High Efficiency Video Codec (HEVC), ITU-T H.266/Versatile Video Codec (VVC), and extensions of these standards, as well as proprietary Video codecs/formats such as AOMedia Video 1 (AV 1) developed by the open media alliance. By implementing such video codec techniques, video devices may more efficiently transmit, receive, encode, decode, and/or store digital video information.
Video coding techniques include spatial (intra-picture) prediction and/or temporal (inter-picture) prediction to reduce or eliminate redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video picture or a portion of a video picture) may be partitioned into video blocks, which may also be referred to as a Coding Tree Unit (CTU), a Coding Unit (CU), and/or a coding node. Video blocks in an intra-coding (I) slice of a picture are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same picture. Video blocks in an inter-codec (P or B) slice of a picture may use spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures. A picture may be referred to as a frame and a reference picture may be referred to as a reference frame.
Disclosure of Invention
In general, this disclosure describes techniques for encoding and decoding video data using various combinations of Overlapped Block Motion Compensation (OBMC), combined inter/intra prediction (CIIP), and Luma Mapping and Chroma Scaling (LMCS). The present disclosure describes various techniques in which these various codec modes may be combined or excluded depending on which modes are enabled or disabled.
In one example, a method of decoding video data includes generating an inter-predicted block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
In another example, an apparatus for decoding video data includes a memory configured to store video data; and one or more processors implemented in the circuitry and configured to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
In another example, a computer-readable storage medium having instructions stored thereon that, when executed, cause a processor to generate an inter-predicted block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
In another example, an apparatus for decoding video data includes means for generating an inter prediction block of a current block of video data; means for generating an intra-predicted block of a current block of video data; means for generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and means for decoding a current block of video data using the final prediction block.
The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.
Drawings
Fig. 1 is a block diagram illustrating an example video encoding and decoding system that may perform the techniques of this disclosure.
Fig. 2 is a block diagram illustrating an example video encoder that may perform the techniques of this disclosure.
Fig. 3 is a block diagram illustrating an example video decoder that may perform the techniques of this disclosure.
Fig. 4 is a conceptual diagram illustrating an example architecture for performing Luma Mapping (LMCS) with chroma scaling.
Fig. 5A and 5B are conceptual diagrams illustrating examples of sub-blocks used in Overlapped Block Motion Compensation (OBMC).
Fig. 6 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure.
Fig. 7 is a flowchart illustrating an example method for decoding a current block in accordance with the techniques of this disclosure.
Fig. 8 is a flowchart illustrating an example method of jointly predicting blocks of video data using OBMC and CIIP.
Fig. 9 is a flowchart illustrating an example method of jointly predicting blocks of video data using CIIP, OBMC, and LMCS.
Fig. 10 is a flowchart illustrating another example method of jointly predicting blocks of video data using CIIP, OBMC, and LMCS.
Detailed Description
Fig. 1 is a block diagram illustrating an example video encoding and decoding system 100 that may perform the techniques of this disclosure. The techniques of this disclosure are generally directed to encoding (encoding and/or decoding) video data. Generally, video data includes any data used to process video. Thus, video data may include raw, non-decoded video, encoded video, decoded (e.g., reconstructed) video, and video metadata, such as signaling data.
As shown in fig. 1, in this example, the system 100 includes a source device 102 that provides encoded video data to be decoded and displayed by a destination device 116. Specifically, the source device 102 provides video data to the destination device 116 via the computer readable medium 110. The source device 102 and the destination device 116 may comprise any of a variety of devices including desktop computers, notebook (i.e., laptop) computers, mobile devices, tablet computers, set-top boxes, telephone handsets (such as smartphones), televisions, cameras, display devices, digital media players, video game consoles, video streaming devices, broadcast receiver devices, and the like. In some cases, the source device 102 and the destination device 116 may be equipped for wireless communication, and thus may be referred to as wireless communication devices.
In the example of fig. 1, source device 102 includes video source 104, memory 106, video encoder 200, and output interface 108. Destination device 116 includes input interface 122, video decoder 300, memory 120, and display device 118. In accordance with the present disclosure, the video encoder 200 of the source device 102 and the video decoder 300 of the destination device 116 may be configured to apply techniques for encoding and decoding video data using various combinations of Overlapped Block Motion Compensation (OBMC), combined inter/intra prediction (CIIP), and Luma Mapping and Chroma Scaling (LMCS). Thus, source device 102 represents an example of a video encoding device, and destination device 116 represents an example of a video decoding device. In other examples, the source device and the destination device may include other components or arrangements. For example, source device 102 may receive video data from an external video source, such as an external camera. Similarly, the destination device 116 may interface with an external display device instead of including an integrated display device.
The system 100 as shown in fig. 1 is merely one example. In general, any digital video encoding and/or decoding device may perform techniques for encoding and decoding video data using various combinations of Overlapped Block Motion Compensation (OBMC), combined inter/intra prediction (CIIP), and Luma Mapping and Chroma Scaling (LMCS). The source device 102 and the destination device 116 are merely examples of such codec devices, wherein the source device 102 generates decoded video data for transmission to the destination device 116. The present disclosure refers to "codec" devices as devices that perform the codec (encoding and/or decoding) of data. Thus, the video encoder 200 and the video decoder 300 represent examples of codec devices, specifically, a video encoder and a video decoder, respectively. In some examples, source device 102 and destination device 116 may operate in a substantially symmetrical manner such that each of source device 102 and destination device 116 includes video encoding and decoding components. Thus, the system 100 may support unidirectional or bidirectional video transmission (e.g., for video streaming, video playback, video broadcasting, or video telephony) between the source device 102 and the destination device 116.
In general, video source 104 represents a source of video data (i.e., raw, non-decoded video data) and provides a succession of pictures (also referred to as "frames") of video data to video encoder 200, which video encoder 200 encodes the data of the pictures. The video source 104 of the source device 102 may include a video capture device such as a camera, a video archive containing previously captured raw video, and/or a video feed interface that receives video from a video content provider. As yet another alternative, the video source 104 may generate computer graphics-based data as the source video, or a combination of live video, archived video, and computer-generated video. In each case, the video encoder 200 encodes captured, pre-captured, or computer-generated video data. The video encoder 200 may rearrange the pictures from the received order (sometimes referred to as the "display order") to a codec order for encoding and decoding. The video encoder 200 may generate a bitstream including the encoded video data. The source device 102 may then output the encoded video data onto the computer readable medium 110 via the output interface 108 for receipt and/or retrieval by an input interface 122, such as the destination device 116.
The memory 106 of the source device 102 and the memory 120 of the destination device 116 represent general purpose memory. In some examples, the memories 106, 120 may store raw video data, such as raw video from the video source 104 and raw decoded video data from the video decoder 300. Additionally or alternatively, the memories 106, 120 may store software instructions executable by, for example, the video encoder 200 and the video decoder 300, respectively. Although in this example, memory 106 and memory 120 are shown separately from video encoder 200 and video decoder 300, it should be understood that video encoder 200 and video decoder 300 may also include internal memory for functionally similar or equivalent purposes. Further, the memories 106, 120 may store encoded video data, for example, data output from the video encoder 200 and input to the video decoder 300. In some examples, a portion of the memory 106, 120 may be allocated as one or more video buffers, e.g., to store raw, decoded, and/or encoded video data.
Computer-readable medium 110 may represent any type of medium or device capable of transmitting encoded video data from source device 102 to destination device 116. In one example, the computer-readable medium 110 represents a communication medium to enable the source device 102 to transmit encoded video data directly to the destination device 116 in real-time, e.g., via a radio frequency network or a computer-based network. According to a communication standard, such as a wireless communication protocol, output interface 108 may modulate a transmission signal including encoded video data, and input interface 122 may demodulate a received transmission signal. The communication medium may include any wireless or wired communication medium such as a Radio Frequency (RF) spectrum or one or more physical transmission lines. The communication medium may form part of a packet-based network, such as a local area network, a wide area network, or a global network such as the internet. The communication medium may include a router, switch, base station, or any other device that facilitates communication from source device 102 to destination device 116.
In some examples, source device 102 may output encoded data from output interface 108 to storage device 112. Similarly, destination device 116 may access encoded data from storage device 112 via input interface 122. Storage device 112 may include any of a variety of distributed or locally accessed data storage media such as hard disks, blu-ray discs, DVDs, CD-ROMs, flash memory, volatile or non-volatile memory, or any other suitable digital storage media for storing encoded video data.
In some examples, source device 102 may output encoded video data to file server 114 or another intermediate storage device that may store the encoded video generated by source device 102. The destination device 116 may access the stored video data from the file server 114 via streaming or download.
File server 114 may be any type of server device capable of storing encoded video data and transmitting the encoded video data to destination device 116. File server 114 may represent a web server (e.g., for a website), a server configured to provide file transfer protocol services, such as File Transfer Protocol (FTP) or file delivery over unidirectional transport (FLUTE) protocol, content Delivery Network (CDN) devices, hypertext transfer protocol (HTTP) servers, multimedia Broadcast Multicast Services (MBMS) or enhanced MBMS (eMBMS) servers, and/or Network Attached Storage (NAS) devices. The file server 114 may additionally or alternatively implement one or more HTTP streaming protocols, such as dynamic adaptive streaming over HTTP (DASH), live streaming over HTTP (HLS), real-time streaming protocol (RTSP), dynamic streaming over HTTP, and the like.
The destination device 116 may access the encoded video data from the file server 114 via any standard data connection, including an internet connection. This may include a wireless channel (e.g., wi-Fi connection), a wired connection (e.g., digital Subscriber Line (DSL), cable modem, etc.), or a combination of both, that is adapted to access encoded video data stored on file server 114. The input interface 122 may be configured to operate in accordance with any one or more of the various protocols described above for retrieving or receiving media data from the file server 114 or other such protocols for retrieving media data.
Output interface 108 and input interface 122 may represent wireless transmitters/receivers, modems, wired network components (e.g., ethernet cards), wireless communication components operating according to any of a variety of IEEE 802.11 standards, or other physical components. In examples where output interface 108 and input interface 122 include wireless componentsThe output interface 108 and the input interface 122 may be configured to transmit data such as encoded video data according to cellular communication standards such as 4G, 4G-LTE (long term evolution), LTE-advanced, 5G, etc. In some examples where output interface 108 includes a wireless transmitter, output interface 108 and input interface 122 may be configured to communicate with a wireless communication device in accordance with a wireless communication device such as an IEEE 802.11 specification, an IEEE 802.15 specification (e.g., )、/>Other wireless standards such as standards to transmit data such as encoded video data. In some examples, source device 102 and/or destination device 116 may include respective system-on-chip (SoC) devices. For example, source device 102 may comprise a SoC device that performs the functions attributed to video encoder 200 and/or output interface 108, and destination device 116 may comprise a SoC device that performs the functions attributed to video decoder 300 and/or input interface 122.
The techniques of this disclosure may be applied to video encoding and decoding to support any of a variety of multimedia applications, such as over-the-air television broadcasting, cable television transmission, satellite television transmission, internet streaming video transmission (such as dynamic adaptive streaming over HTTP (DASH)), decoding of digital video encoded onto a data storage medium, digital video stored on a data storage medium, or other applications.
The input interface 122 of the destination device 116 receives the encoded video bitstream from the computer readable medium 110 (e.g., communication medium, storage device 112, file server 114, etc.). The encoded video bitstream may include signaling information defined by the video encoder 200, which is also used by the video decoder 300, such as syntax elements having values describing characteristics and/or processing of video blocks or other decoded units (e.g., slices, pictures, groups of pictures, sequences, etc.). The display device 118 displays the decoded pictures of the decoded video data to a user. Display device 118 may represent any of a variety of display devices, such as a Liquid Crystal Display (LCD), a plasma display, an Organic Light Emitting Diode (OLED) display, or other type of display device.
Although not shown in fig. 1, in some examples, the video encoder 200 and the video decoder 300 may each be integrated with an audio encoder and/or an audio decoder, and may include appropriate MUX-DEMUX units or other hardware and/or software to process multiplexed streams including both audio and video in a common data stream.
Video encoder 200 and video decoder 300 may each be implemented as any of a variety of suitable encoder and/or decoder circuits, such as one or more microprocessors, digital Signal Processors (DSPs), application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs), discrete logic, software, hardware, firmware or any combinations thereof. When the techniques are implemented in part in software, a device may store instructions of the software in a suitable non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Each of the video encoder 200 and the video decoder 300 may be included in one or more encoders or decoders, any of which may be integrated as part of a combined encoder/decoder (CODEC) in the respective device. Devices including video encoder 200 and/or video decoder 300 may include integrated circuits, microprocessors, and/or wireless communication devices, such as cellular telephones.
The video encoder 200 and the video decoder 300 may operate in accordance with a video codec standard, such as ITU-t h.265, also known as High Efficiency Video Codec (HEVC) or an extension thereof, such as a multiview and/or scalable video codec extension. Alternatively, the video encoder 200 and video decoder 300 may operate in accordance with other proprietary or industry standards, such as ITU-t h.266, also known as universal video codec (VVC). In other examples, the Video encoder 200 and Video decoder 300 may operate in accordance with proprietary Video codecs/formats, such as AOMedia Video 1 (AV 1), extensions of AV1, and/or subsequent versions of AV1 (e.g., AV 2). In other examples, video encoder 200 and video decoder 300 may operate in accordance with other proprietary formats or industry standards. However, the techniques of this disclosure are not limited to any particular codec standard or format. In general, video encoder 200 and video decoder 300 may be configured to perform the techniques of this disclosure in conjunction with any video codec technique that uses various combinations of Overlapped Block Motion Compensation (OBMC), combined inter/intra prediction (CIIP), and Luma Mapping and Chroma Scaling (LMCS).
In general, the video encoder 200 and the video decoder 300 may perform block-based encoding and decoding of pictures. The term "block" generally refers to a structure that includes data to be processed (e.g., data to be encoded, decoded, or otherwise used in an encoding process and/or a decoding process). For example, a block may comprise a two-dimensional matrix of samples of brightness and/or color data. In general, video encoder 200 and video decoder 300 may codec video data represented in YUV (e.g., Y, cb, cr) format. That is, the video encoder 200 and the video decoder 300 may codec brightness and color tone components, which may include both red and blue hue components, instead of red, green, and blue (RGB) data of samples of a picture. In some examples, the video encoder 200 converts the received RGB formatted data to a YUV representation prior to encoding, and the video decoder 300 converts the YUV representation to RGB format. Alternatively, a preprocessing and post-processing unit (not shown) may perform these conversions.
The present disclosure may generally relate to encoding and decoding (e.g., encoding and decoding) of a picture, including processes of encoding or decoding data of the picture. Similarly, the present disclosure may relate to the coding of blocks of pictures, including processes of coding or decoding data of the blocks, e.g., prediction and/or residual coding. The encoded video bitstream typically includes a series of values representing codec decisions (e.g., codec modes) and syntax elements for picture-to-block partitioning. Thus, reference to a codec picture or block should generally be understood as a value of a syntax element that the codec forms the picture or block.
HEVC defines various blocks, including Coding Units (CUs), prediction Units (PUs), and Transform Units (TUs). According to HEVC, a video codec, such as video encoder 200, partitions a Coding Tree Unit (CTU) into CUs according to a quadtree structure. That is, the video codec partitions CTUs and CUs into four equal, non-overlapping squares, and each node of the quadtree has zero or four child nodes. A node without child nodes may be referred to as a "leaf node," and a CU of such a leaf node may include one or more PUs and/or one or more TUs. The video codec may also partition PUs and TUs. For example, in HEVC, a Residual Quadtree (RQT) represents a partition of TUs. In HEVC, PY represents inter prediction data and TU represents residual data. The intra-predicted CU includes intra-prediction information, such as an intra-mode indication.
As another example, the video encoder 200 and the video decoder 300 may be configured to operate according to VVC. According to VVC, a video codec, such as video encoder 200, partitions a picture into a plurality of Codec Tree Units (CTUs). The video encoder 200 may partition the CTUs according to a tree structure, such as a quadtree-binary tree (QTBT) structure or a multi-type tree (MTT) structure. QTBT structures remove the concept of multiple partition types, such as separation between CUs, PUs, and TUs of HEVC. The QTBT structure includes two layers: a first layer partitioned according to a quadtree partitioning and a second layer partitioned according to a binary tree partitioning. The root node of the QTBT structure corresponds to the CTU. Leaf nodes of the binary tree correspond to coding and decoding units (CUs).
In the MTT partitioning structure, blocks may be partitioned using a Quadtree (QT) partition, a Binary Tree (BT) partition, and one or more types of Trigeminal Tree (TT) (also referred to as Ternary Tree (TT)) partitions. A trigeminal or ternary tree partition is a partition that divides a block into three sub-blocks. In some examples, the trigeminal or ternary tree partitioning divides a block into three sub-blocks without dividing the original block by center. The segmentation types (e.g., QT, BT, and TT) in MTT may be symmetrical or asymmetrical.
When operating according to the AV1 codec, the video encoder 200 and the video decoder 300 may be configured to codec video data in block units. In AV1, the largest codec block that can be processed is called a super block. In AV1, the superblock may be any of 128x128 luminance samples or 64x64 luminance samples. However, in a subsequent video codec format (e.g., AV 2), the super block may be defined by a different (e.g., larger) luma sample size. In some examples, the superblock is the top level of the block quadtree. The video encoder 200 may also partition the super block into smaller codec blocks. The video encoder 200 may use square or non-square partitioning to partition super blocks and other codec blocks into smaller blocks. Non-square blocks may include N/2xN, nxN/2, N/4xN, and NxN/4 blocks. The video encoder 200 and the video decoder 300 may perform separate prediction and transformation processes for each codec block.
AV1 also defines slices of video data. A slice is a rectangular array of super blocks that can be encoded and decoded independently of other slices. That is, the video encoder 200 and the video decoder 300 may respectively encode and decode the intra-slice codec blocks without using video data from other slices. However, the video encoder 200 and the video decoder 300 may perform filtering across slice boundaries. The sheets may be uniform or non-uniform in size. Slice-based encoding and decoding may enable parallel processing and/or multithreading of encoder and decoder implementations.
In some examples, the video encoder 200 and the video decoder 300 may use a single QTBT or MTT structure to represent each of the luma component and the chroma components, while in other examples, the video encoder 200 and the video decoder 300 may use two or more QTBT or MTT structures, such as one QTBT/MTT structure for the luma component and another QTBT/MTT structure for the two chroma components (or two QTBT/MTT structures for the respective chroma components).
The video encoder 200 and video decoder 300 may be configured to use quadtree partitioning, QTBT partitioning, MTT partitioning, superblock partitioning, or other partitioning structures.
In some examples, the CTU includes a Coding Tree Block (CTB) of luma samples of a picture having three sample arrays, two corresponding CTBs of chroma samples, or a CTB of samples of a monochrome picture or a picture encoded using three separate color planes, and a syntax structure used to encode and decode the samples. CTBs may be blocks of nxn samples of some value of N, such that dividing a component into CTBs is a sort of partitioning. The component may be from 4:2: 0. 4:2: 2. 4:4: an array or single spot of one of three arrays (luminance and two chromaticities) of a picture in a 4-color format, or an array or single spot of an array of a picture in a monochrome format. In some examples, the codec block is an mxn sample block of some values of M and N, such that dividing CTBs into codec blocks is a sort of partitioning.
Blocks (e.g., CTUs or CUs) may be grouped in pictures in various ways. As one example, a tile may refer to a rectangular region of CTU rows within a particular slice in a picture. A tile may be a rectangular region of CTUs within a particular tile column and a particular tile row in a picture. A slice column refers to a rectangular region of a CTU whose height is equal to the height of a picture and whose width is specified by syntax elements (e.g., syntax elements such as in a picture parameter set). A slice line refers to a rectangular region of a CTU whose height is specified by a syntax element (e.g., such as a syntax element in a picture parameter set) and whose width is equal to the width of a picture.
In some examples, a tile may be partitioned into multiple tiles, each tile may include one or more rows of CTUs within the tile. A tile that is not divided into multiple tiles may also be referred to as a tile. However, tiles that are a proper subset of tiles may not be referred to as tiles. Tiles in a picture may also be arranged in slices. A slice may be an integer number of tiles of a picture that may be contained exclusively in a single Network Abstraction Layer (NAL) unit. In some examples, a slice includes multiple complete slices or complete tiles that include only one contiguous sequence of slices.
The present disclosure may use "N x N" and "N by N" interchangeably to represent the sample size of a block (such as a CU or other video block) in the vertical and horizontal dimensions, e.g., 16 x 16 samples or 16 by 16 samples. Generally, a 16×16 CU has 16 samples in the vertical direction (y=16), and 16 samples in the horizontal direction (x=16). Similarly, an nxn CU typically has N samples in the vertical direction and N samples in the horizontal direction, where N represents a non-negative integer value. The samples in a CU may be arranged in rows and columns. Further, a CU does not necessarily have to have the same number of samples in the horizontal direction as in the vertical direction. For example, a CU may include n×m samples, where M is not necessarily equal to N.
The video encoder 200 encodes video data of a CU representing prediction and/or residual information, as well as other information. The prediction information indicates how the CU is to be predicted in order to form a prediction block of the CU. The residual information generally represents sample-by-sample differences between samples of the CU and the prediction block prior to encoding.
To predict a CU, video encoder 200 may typically form a prediction block of the CU by inter-prediction or intra-prediction. Inter-prediction generally refers to predicting a CU from data of a previously decoded picture, while intra-prediction generally refers to predicting a CU from previously decoded data of the same picture. To perform inter prediction, the video encoder 200 may generate a prediction block using one or more motion vectors. Video encoder 200 typically performs a motion search to identify reference blocks that closely match the CU (e.g., in terms of differences between the CU and the reference blocks). The video encoder 200 may calculate a difference metric using a Sum of Absolute Differences (SAD), a Sum of Squared Differences (SSD), a Mean Absolute Difference (MAD), a Mean Squared Difference (MSD), or other such difference calculation to determine whether the reference block closely matches the current CU. In some examples, video encoder 200 may use unidirectional prediction or bi-directional prediction to predict the current CU.
Some examples of VVCs also provide affine motion compensation modes, which may be considered inter prediction modes. In affine motion compensation mode, the video encoder 200 may determine two or more motion vectors representing non-translational motion (such as zoom in or out, rotation, perspective motion, or other irregular motion types).
To perform intra prediction, the video encoder 200 may select an intra prediction mode to generate a prediction block. Some examples of VVCs provide sixty-seven intra-prediction modes, including various directional modes, as well as planar modes and DC modes. In general, video encoder 200 selects an intra prediction mode that describes predicting samples of a current block (e.g., a block of a CU) from neighboring samples of the current block. Assuming that the video encoder 200 encodes CTUs and CUs in raster scan order (left to right, top to bottom), such samplings may generally be above, above to the left or left of the current block in the same picture as the current block.
The video encoder 200 encodes data representing a prediction mode of the current block. For example, for inter prediction modes, the video encoder 200 may encode data indicating which of the various available inter prediction modes is used, and motion information for the corresponding mode. For unidirectional or bi-directional inter prediction, for example, the video encoder 200 may encode motion vectors using Advanced Motion Vector Prediction (AMVP) or merge mode. The video encoder 200 may encode the motion vectors for the affine motion compensation mode using a similar mode.
AV1 includes two general techniques for encoding and decoding codec blocks of video data. The two common techniques are intra-prediction (e.g., intra-prediction or spatial-prediction) and inter-prediction (e.g., inter-prediction or temporal-prediction). In the context of AV1, when a block of a current frame of video data is predicted using an intra prediction mode, the video encoder 200 and the video decoder 300 do not use video data from other frames of video data. For most intra-prediction modes, the video encoder 200 encodes a block of the current frame based on the difference between the sample value in the current block and the prediction value generated from the reference sample in the same frame. The video encoder 200 determines a prediction value generated from the reference sample point based on the intra prediction mode.
After prediction (such as intra prediction or inter prediction of a block), the video encoder 200 may calculate residual data for the block. Residual data (such as a residual block) represents a sample-by-sample difference between a block and a prediction block of the block, the prediction block being formed using a corresponding prediction mode. The video encoder 200 may apply one or more transforms to the residual block to produce transformed data in the transform domain instead of the sample domain. For example, video encoder 200 may apply a Discrete Cosine Transform (DCT), an integer transform, a wavelet transform, or a conceptually similar transform to the residual video data. Additionally, the video encoder 200 may apply a secondary transform after the first transform, such as a mode dependent inseparable secondary transform (MDNSST), a signal dependent transform, a Karhunen-Loeve transform (KLT), and the like. The video encoder 200 generates transform coefficients after applying one or more transforms.
As described above, after generating any transform of transform coefficients, the video encoder 200 may perform quantization of the transform coefficients. Quantization generally refers to a process in which transform coefficients are quantized to potentially reduce the amount of data used to represent the transform coefficients to provide further compression. By performing the quantization process, the video encoder 200 may reduce the bit depth associated with some or all of the transform coefficients. For example, the video encoder 200 may round an n-bit value to an m-bit value during quantization, where n is greater than m. In some examples, to perform quantization, the video encoder 200 may perform a bit-wise right shift of the value to be quantized.
After quantization, the video encoder 200 may scan the transform coefficients, producing a one-dimensional vector from a two-dimensional matrix comprising the quantized transform coefficients. The scan may be designed to place higher energy (and therefore lower frequency) transform coefficients in front of the vector and lower energy (and therefore higher frequency) transform coefficients in back of the vector. In some examples, video encoder 200 may scan the quantized transform coefficients using a predefined scan order to produce a serialized vector and then entropy encode the quantized transform coefficients of the vector. In other examples, video encoder 200 may perform adaptive scanning. After scanning the quantized transform coefficients to form a one-dimensional vector, the video encoder 200 may entropy encode the one-dimensional vector, e.g., according to context-adaptive binary arithmetic coding (CABAC). The video encoder 200 may also entropy encode values of syntax elements that describe metadata associated with the encoded video data for use by the video decoder 300 in decoding the video data.
To perform CABAC, the video encoder 200 may assign context within the context model to the symbol to be transmitted. The context may relate to, for example, whether the adjacent value of the symbol is a zero value. The probability determination may be based on the context assigned to the symbol.
The video encoder 200 may also generate syntax data to the video decoder 300, such as block-based syntax data, picture-based syntax data, and sequence-based syntax data, for example, in a picture header, a block header, a slice header, or other syntax data, such as a Sequence Parameter Set (SPS), a Picture Parameter Set (PPS), or a Video Parameter Set (VPS). The video decoder 300 may similarly decode this syntax data to determine how to decode the corresponding video data.
In this way, video encoder 200 may generate a bitstream that includes encoded video data (e.g., syntax elements describing picture-to-block (e.g., CU) partitioning and prediction and/or residual information for the block). Finally, the video decoder 300 may receive the bitstream and decode the encoded video data.
In general, the video decoder 300 performs a process reciprocal to that performed by the video encoder 200 to decode encoded video data of a bitstream. For example, the video decoder 300 may decode the values of the syntax elements of the bitstream using CABAC in a manner substantially similar to (although reciprocal to) the CABAC encoding process of the video encoder 200. The syntax element may define partition information for partitioning a picture into CTUs and partitioning each CTU according to a corresponding partition structure such as a QTBT structure to define CUs of the CTU. Syntax elements may also define prediction and residual information for blocks (e.g., CUs) of video data.
The residual information may be represented by, for example, quantized transform coefficients. The video decoder 300 may inverse quantize and inverse transform the quantized transform coefficients of the block to reconstruct the residual block of the block. The video decoder 300 forms a prediction block of a block using a signaled prediction mode (intra prediction or inter prediction) and associated prediction information (e.g., motion information for inter prediction). The video decoder 300 may then combine the prediction block and the residual block (on a sample-by-sample basis) to reproduce the original block. The video decoder 300 may perform additional processing, such as performing a deblocking process to reduce visual artifacts along the boundaries of the blocks.
The present disclosure may generally relate to "signaling" certain information, such as syntax elements. The term "signaling" may generally refer to the communication of syntax elements and/or values of other data used to decode encoded video data. That is, the video encoder 200 may signal the value of the syntax element in the bitstream. Typically, signaling refers to generating values in the bit stream. As described above, the source device 102 may stream the bits to the destination device 116 in substantially real-time or non-real-time (such as may occur when storing the syntax elements to the storage device 112 for later retrieval by the destination device 116).
In accordance with the techniques of this disclosure, video encoder 200 and video decoder 300 may encode (encode and/or decode) blocks of video data using various combinations of OBMC, CIIP, and/or LMCS, as discussed in more detail below.
Fig. 2 is a block diagram illustrating an example video encoder 200 that may perform the techniques of this disclosure. Fig. 2 is provided for purposes of explanation and should not be considered limiting of the techniques broadly illustrated and described in this disclosure. For purposes of explanation, this disclosure describes a video encoder 200 in accordance with techniques of VVC (ITU-T h.266) and HEVC (ITU-T h.265). However, the techniques of this disclosure may be performed by video encoding devices configured as other video codec standards and video codec formats (such as AV1 and successor to AV1 video codec formats).
In the example of fig. 2, video encoder 200 includes video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, luma mapping with chroma scaling (LMCS) unit 228, filter unit 216, decoded Picture Buffer (DPB) 218, and entropy encoding unit 220. Any or all of video data memory 230, mode selection unit 202, residual generation unit 204, transform processing unit 206, quantization unit 208, inverse quantization unit 210, inverse transform processing unit 212, reconstruction unit 214, LMCS unit 228, filter unit 216, DPB 218, and entropy encoding unit 220 may be implemented in one or more processors or processing circuits. For example, the elements of video encoder 200 may be implemented as one or more circuits or logic elements as part of a hardware circuit or as part of a processor, ASIC, or FPGA. Furthermore, the video encoder 200 may include additional or alternative processors or processing circuits to perform these and other functions.
Video data memory 230 may store video data to be encoded by components of video encoder 200. Video encoder 200 may receive video data stored in video data store 230 from, for example, video source 104 (fig. 1). DPB 218 may serve as a reference picture memory that stores reference video data for use by video encoder 200 in predicting subsequent video data. Video data memory 230 and DPB 218 may be formed from any of a variety of memory devices, such as Dynamic Random Access Memory (DRAM), including Synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. Video data memory 230 and DPB 218 may be provided by the same memory device or separate memory devices. In various examples, video data memory 230 may be on-chip (as illustrated) with other components of video encoder 200, or off-chip with respect to those components.
In this disclosure, references to video data memory 230 should not be construed as limited to memory internal to video encoder 200 unless specifically described as such, or to memory external to video encoder 200 unless specifically described as such. Conversely, references to video data memory 230 should be understood to refer to a memory that stores video data received by video encoder 200 for encoding (e.g., video data of a current block to be encoded). The memory 106 of fig. 1 may also provide temporary storage of the output from the various units of the video encoder 200.
Various elements of fig. 2 are illustrated to aid in understanding the operations performed by video encoder 200. These units may be implemented as fixed function circuits, programmable circuits or a combination thereof. The fixed function circuit refers to a circuit that provides a specific function and presets an operation that can be performed. Programmable circuitry refers to circuitry that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For example, the programmable circuit may run software or firmware that causes the programmable circuit to operate in a manner defined by instructions of the software or firmware. Fixed function circuitry may execute software instructions (e.g., to receive parameters or output parameters) but the type of operation that fixed function circuitry performs is typically not variable. In some examples, one or more of the units may be different circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be integrated circuits.
The video encoder 200 may include an Arithmetic Logic Unit (ALU), a basic functional unit (EFU), digital circuitry, analog circuitry, and/or a programmable core formed from programmable circuitry. In examples where the operation of video encoder 200 is performed using software executed by programmable circuitry, memory 106 (fig. 1) may store instructions (e.g., object code) of the software received and executed by video encoder 200, or another memory (not shown) within video encoder 200 may store such instructions.
The video data memory 230 is configured to store received video data. The video encoder 200 may retrieve pictures of the video data from the video data memory 230 and provide the video data to the residual generation unit 204 and the mode selection unit 202. The video data in the video data memory 230 may be raw video data to be encoded.
The mode selection unit 202 comprises a motion estimation unit 222, a motion compensation unit 224 and an intra prediction unit 226. The mode selection unit 202 may include additional functional units to perform video prediction according to other prediction modes. As an example, mode selection unit 202 may include a palette unit, an intra block copy unit (which may be part of motion estimation unit 222 and/or motion compensation unit 224), an affine unit, a Linear Model (LM) unit, and the like.
Mode selection unit 202 typically coordinates multiple encoding passes to test combinations of encoding parameters and resulting rate-distortion values for such combinations. The coding parameters may include CTU-to-CU partitioning, prediction modes of the CU, transform types of residual data of the CU, quantization parameters of residual data of the CU, and the like. The mode selection unit 202 may finally select a combination of coding parameters having better rate-distortion values than the other tested combinations.
Video encoder 200 may segment pictures retrieved from video data store 230 into a series of CTUs and encapsulate one or more CTUs within a slice. The mode selection unit 202 may partition CTUs of pictures according to a tree structure (e.g., the MTT structure, QTBT structure, superblock structure, or quadtree structure described above). As described above, the video encoder 200 may form one or more CUs by dividing CTUs according to a tree structure. Such CUs may also be commonly referred to as "video blocks" or "blocks.
Typically, mode selection unit 202 also controls its components (e.g., motion estimation unit 222, motion compensation unit 224, and intra prediction unit 226) to generate a prediction block for the current block (e.g., the overlapping portion of PU and TU in the current CU or HEVC). To inter-predict the current block, motion estimation unit 222 may perform a motion search to identify one or more closely matching reference blocks in one or more reference pictures (e.g., one or more previously decoded pictures stored in DPB 218). Specifically, the motion estimation unit 222 may calculate a value indicating that the potential reference block has the same phase as the current block, for example, according to a Sum of Absolute Differences (SAD), a Sum of Squared Differences (SSD), a Mean Absolute Difference (MAD), a Mean Squared Difference (MSD), and the like. The motion estimation unit 222 may typically perform these calculations using sample-by-sample differences between the current block and the reference block under consideration. The motion estimation unit 222 may identify the reference block having the lowest value resulting from these calculations, indicating the reference block that most closely matches the current block.
The motion estimation unit 222 may form one or more Motion Vectors (MVs) defining the position of a reference block in a reference picture relative to the position of a current block in a current picture. The motion estimation unit 222 may then provide the motion vectors to the motion compensation unit 224. For example, for unidirectional inter prediction, the motion estimation unit 222 may provide a single motion vector, while for bi-directional inter prediction, the motion estimation unit 222 may provide two motion vectors. The motion compensation unit 224 may then generate a prediction block using the motion vector. For example, the motion compensation unit 224 may retrieve data of the reference block using the motion vector. As another example, if the motion vector has fractional sample precision, the motion compensation unit 224 may interpolate the values of the prediction block according to one or more interpolation filters. Furthermore, for bi-directional inter prediction, the motion compensation unit 224 may retrieve data of two reference blocks identified by respective motion vectors and combine the retrieved data (e.g., by a sample-wise average or a weighted average).
When operating in accordance with the AV1 video codec format, the motion estimation unit 222 and the motion compensation unit 224 may be configured to encode codec blocks (e.g., both luma and chroma codec blocks) of video data using translational motion compensation, affine motion compensation, overlapped Block Motion Compensation (OBMC), and/or composite inter-frame intra prediction.
As another example, for intra prediction or intra prediction codec, the intra prediction unit 226 may generate a prediction block from samples adjacent to the current block. For example, for directional modes, intra-prediction unit 226 may typically mathematically combine the values of neighboring samples and populate these calculated values in a defined direction across the current block to produce a predicted block. As another example, for the DC mode, the intra prediction unit 226 may calculate an average value of neighboring samples of the current block and generate a prediction block to include the resulting average value of each sample of the prediction block.
When operating in accordance with the AV1 video codec format, the intra-prediction unit 226 may be configured to encode codec blocks (e.g., both luma and chroma codec blocks) of video data using directional intra-prediction, non-directional intra-prediction, recursive filter intra-prediction, luma to Chroma (CFL) prediction, intra-block copy (IBC), and/or palette modes. The mode selection unit 202 may include additional functional units to perform video prediction according to other prediction modes.
The mode selection unit 202 supplies the prediction block to the residual generation unit 204. The residual generation unit 204 receives the original, non-decoded version of the current block from the video data store 230 and the prediction block from the mode selection unit 202. The residual generation unit 204 calculates a sample-by-sample difference between the current block and the prediction block. The resulting sample-by-sample difference defines the residual block of the current block. In some examples, residual generation unit 204 may also determine differences between sample values in the residual block to generate the residual block using Residual Differential Pulse Code Modulation (RDPCM). In some examples, residual generation unit 204 may be formed using one or more subtractor circuits that perform binary subtraction.
In examples where mode selection unit 202 partitions a CU into PUs, each PU may be associated with a luma prediction unit and a corresponding chroma prediction unit. Video encoder 200 and video decoder 300 may support PUs having various sizes. As indicated above, the size of a CU may refer to the size of the luma codec block of the CU, while the size of a PU may refer to the size of the luma prediction unit of the PU. Assuming that the size of a particular CU is 2nx2n, the video encoder 200 may support 2 nx2n or nxn PU sizes for intra prediction and 2 nx2n, 2 nx N, N x 2N, N x N or similar symmetric PU sizes for inter prediction. The video encoder 200 and the video decoder 300 may also support asymmetric partitioning of PU sizes of 2nxnu, 2nxnd, nl×2n, and nr×2n for inter prediction.
In examples where the mode selection unit 202 does not further partition the CUs into PUs, each CU may be associated with a luma codec block and a corresponding chroma codec block. As above, the size of a CU may refer to the size of a luma codec block of the CU. The video encoder 200 and the video decoder 300 may support CU sizes of 2nx2n, 2nxn, or nx2n.
For other video coding techniques, such as intra block copy mode coding, affine mode coding, and Linear Model (LM) mode coding, as some examples, mode selection unit 202 generates a prediction block of the current block being coded via a corresponding unit associated with the coding technique. In some examples, such as palette mode codec, the mode selection unit 202 may not generate a prediction block, but rather generate a syntax element indicating a manner of reconstructing the block based on the selected palette. In such a mode, the mode selection unit 202 may provide these syntax elements to the entropy encoding unit 220 to encode it.
As described above, the residual generation unit 204 receives video data of the current block and the corresponding prediction block. Then, the residual generating unit 204 generates a residual block of the current block. In order to generate the residual block, the residual generation unit 204 calculates a sample-by-sample difference between the prediction block and the current block.
The transform processing unit 206 applies one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "block of transform coefficients"). The transform processing unit 206 may apply various transforms to the residual block to form a block of transform coefficients. For example, transform processing unit 206 may apply a Discrete Cosine Transform (DCT), a direction transform, a Karhunen-Loeve transform (KLT), or a conceptually similar transform to the residual block. In some examples, transform processing unit 206 may perform multiple transforms on the residual block, e.g., a primary transform and a secondary transform, such as a rotational transform. In some examples, transform processing unit 206 does not apply a transform to the residual block.
When operating in accordance with AV1, the transform processing unit 206 may apply one or more transforms to the residual block to generate a block of transform coefficients (referred to herein as a "block of transform coefficients"). The transform processing unit 206 may apply various transforms to the residual block to form a block of transform coefficients. For example, transform processing unit 206 may apply a horizontal/vertical transform combination, which may include a Discrete Cosine Transform (DCT), an Asymmetric Discrete Sine Transform (ADST), a flipped ADST (e.g., an inverted order ADST), and an identity transform (IDTX). When using an identity transform, the transform is skipped in the vertical or horizontal direction. In some examples, the transformation process may be skipped.
The quantization unit 208 may quantize the transform coefficients in the block of transform coefficients to generate a block of quantized transform coefficients. The quantization unit 208 may quantize transform coefficients of the block of transform coefficients according to a Quantization Parameter (QP) value associated with the current block. The video encoder 200 (e.g., via the mode selection unit 202) may adjust the degree of quantization applied to the transform coefficient block associated with the current block by adjusting the QP value associated with the CU. Quantization may introduce information loss and, as a result, the quantized transform coefficients may have lower precision than the original transform coefficients generated by the transform processing unit 206.
The inverse quantization unit 210 and the inverse transform processing unit 212 may apply inverse quantization and inverse transform, respectively, to the quantized transform coefficient block to reconstruct a residual block from the transform coefficient block. The reconstruction unit 214 may generate a reconstructed block corresponding to the current block (although possibly with some degree of distortion) based on the reconstructed residual block and the prediction block generated by the mode selection unit 202. For example, the reconstruction unit 214 may add samples of the reconstructed residual block to corresponding samples of the prediction block generated from the mode selection unit 202 to generate a reconstructed block.
The LMCS unit 228 may be configured to perform luma mapping and chroma scaling. Additional details regarding the LMCS are discussed below with reference to fig. 4. In general, for luma data, LMCS unit 228 may perform in-loop mapping based on an adaptive piecewise linear model, and for chroma data, may perform luma-related chroma residual scaling.
The filter unit 216 may perform one or more filtering operations on the reconstructed block. For example, the filter unit 216 may perform a deblocking operation to reduce blocking artifacts along edges of the CU. In some examples, the operation of the filter unit 216 may be skipped.
When operating in accordance with AV1, the filter unit 216 may perform one or more filter operations on the reconstructed block. For example, the filter unit 216 may perform a deblocking operation to reduce blocking artifacts along edges of the CU. In other examples, filter unit 216 may apply a Constrained Direction Enhancement Filter (CDEF), which may be applied after deblocking, and may include application of an inseparable, nonlinear, low pass direction filter based on the estimated edge direction. The filter unit 216 may also include a loop recovery filter applied after CDEF and may include a separable symmetric normalized wiener filter or a dual bootstrap filter.
Video encoder 200 stores the reconstructed block in DPB 218. For example, in an example where the operation of filter unit 216 is not performed, reconstruction unit 214 may store the reconstructed block to DPB 218. In an example of performing the operation of filter unit 216, filter unit 216 may store the filtered reconstructed block to DPB 218. Motion estimation unit 222 and motion compensation unit 224 may retrieve a reference picture formed from the reconstructed (and possibly filtered) block from DPB 218 to inter-predict a block of a subsequently encoded picture. Furthermore, intra-prediction unit 226 may use the reconstructed block in DPB 218 of the current picture to intra-predict other blocks in the current picture.
In general, entropy encoding unit 220 may entropy encode syntax elements received from other functional components of video encoder 200. For example, entropy encoding unit 220 may entropy encode the quantized transform coefficient block from quantization unit 208. As another example, the entropy encoding unit 220 may entropy encode a prediction syntax element (e.g., motion information for inter prediction or intra mode information for intra prediction) from the mode selection unit 202. The entropy encoding unit 220 may perform one or more entropy encoding operations on syntax elements that are another example of video data to generate entropy encoded data. For example, the entropy encoding unit 220 may perform a Context Adaptive Variable Length Coding (CAVLC) operation, a CABAC operation, a variable-to-variable (V2V) length coding operation, a syntax-based context adaptive binary arithmetic coding (SBAC) operation, a Probability Interval Partitioning Entropy (PIPE) coding operation, an exponential Golomb coding operation, or another type of entropy coding operation on the data. In some examples, entropy encoding unit 220 may operate in a bypass mode that does not entropy encode syntax elements.
The video encoder 200 may output a bitstream that includes entropy encoded syntax elements required to reconstruct blocks of slices or pictures. In particular, the entropy encoding unit 220 may output a bitstream.
According to AV1, the entropy encoding unit 220 may be configured as a symbol-to-symbol adaptive multi-symbol arithmetic codec. The syntax element in AV1 includes an alphabet of N elements, and the context (e.g., probability model) includes a set of N probabilities. The entropy encoding unit 220 may store the probabilities as an n-bit (e.g., 15-bit) Cumulative Distribution Function (CDF). Entropy encoding unit 220 may perform recursive scaling with an update factor based on the alphabet size to update the context.
The above operations are described with respect to blocks. Such description should be understood as the operation for the luma codec block and/or the chroma codec block. As described above, in some examples, the luma codec block and the chroma codec block are a luma component and a chroma component of the CU. In some examples, the luma and chroma codec blocks are luma and chroma components of the PU.
In some examples, for a chroma codec block, the operations performed with respect to a luma codec block need not be repeated. As one example, the operation of identifying a Motion Vector (MV) and a reference picture of a luma codec block does not need to repeat the MV and the reference picture for identifying a chroma block. In contrast, MVs of luma codec blocks may be scaled to determine MVs of chroma blocks, and reference pictures may be the same. As another example, the intra prediction process may be the same for both luma and chroma codec blocks.
Fig. 3 is a block diagram illustrating an example video decoder 300 that may perform the techniques of this disclosure. Fig. 3 is provided for purposes of explanation, and not limitation, of the techniques broadly illustrated and described in the present disclosure. For purposes of explanation, this disclosure describes a video decoder 300 in accordance with techniques of VVC (ITU-T h.266) and HEVC (ITU-T h.265). However, the techniques of this disclosure may be performed by video codec devices configured as other video codec standards.
In the example of fig. 3, video decoder 300 includes a decoded picture buffer (CPB) memory 320, an entropy decoding unit 302, a prediction processing unit 304, an inverse quantization unit 306, an inverse transform processing unit 308, a reconstruction unit 310, a luma map with chroma scaling (LMCS) unit 322, a filter unit 312, and a Decoded Picture Buffer (DPB) 314. Any or all of CPB memory 320, entropy decoding unit 302, prediction processing unit 304, inverse quantization unit 306, inverse transform processing unit 308, reconstruction unit 310, filter unit 312, LMCS unit 322, and DPB 314 may be implemented in one or more processors or processing circuits. For example, the elements of video encoder 300 may be implemented as one or more circuits or logic elements as part of a hardware circuit or as part of a processor, ASIC, or FPGA. Furthermore, the video decoder 300 may include additional or alternative processors or processing circuits to perform these and other functions.
The prediction processing unit 304 includes a motion compensation unit 316 and an intra prediction unit 318. The prediction processing unit 304 may include additional units to perform prediction according to other prediction modes. As an example, the prediction processing unit 304 may include a palette unit, an intra block copy unit (which may form part of the motion compensation unit 316), an affine unit, a Linear Model (LM) unit, and the like. In other examples, video decoder 300 may include more, fewer, or different functional components.
As described above, when operating in accordance with AV1, the motion compensation unit 316 may be configured to decode codec blocks (e.g., both luma and chroma codec blocks) of video data using translational motion compensation, affine motion compensation, OBMC, and/or composite inter-frame intra prediction. As described above, the intra-prediction unit 318 may be configured to decode codec blocks (e.g., both luma and chroma codec blocks) of video data using directional intra-prediction, non-directional intra-prediction, recursive filter intra-prediction, CFL, intra-block copy (IBC), and/or palette modes.
The CPB memory 320 may store video data, such as an encoded video bitstream, to be decoded by components of the video decoder 300. For example, video data stored in the CPB memory 320 may be obtained from the computer-readable medium 110 (fig. 1). The CPB memory 320 may include CPBs that store encoded video data (e.g., syntax elements) from an encoded video bitstream. Also, the CPB memory 320 may store video data other than syntax elements of the decoded pictures, such as temporary data representing outputs from various units of the video decoder 300. DPB 314 typically stores decoded pictures that video decoder 300 may output and/or use as reference video data when decoding subsequent data or pictures of an encoded video bitstream. CPB memory 320 and DPB 314 may be formed from any of a variety of memory devices, such as Dynamic Random Access Memory (DRAM), including Synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. CPB memory 320 and DPB 314 may be provided by the same memory device or separate memory devices. In various examples, CPB memory 320 may be on-chip with other components of video decoder 300, or off-chip with respect to those components.
Additionally or alternatively, in some examples, video decoder 300 may retrieve decoded video data from memory 120 (fig. 1). That is, memory 120 may store data as discussed above with respect to CPB memory 320. Likewise, memory 120 may store instructions to be run by video decoder 300 when some or all of the functions of video decoder 300 are to be implemented in software that is to be run by the processing circuitry of video decoder 300.
Various units shown in fig. 3 are illustrated to aid in understanding the operations performed by video decoder 300. These units may be implemented as fixed function circuits, programmable circuits or a combination thereof. Similar to fig. 2, the fixed function circuit refers to a circuit that provides a specific function and presets operations that can be performed. Programmable circuitry refers to circuitry that can be programmed to perform various tasks and provide flexible functionality in the operations that can be performed. For example, the programmable circuit may run software or firmware that causes the programmable circuit to operate in a manner defined by instructions of the software or firmware. Fixed function circuitry may execute software instructions (e.g., to receive parameters or output parameters) but the type of operation that fixed function circuitry performs is typically not variable. In some examples, one or more of the units may be different circuit blocks (fixed function or programmable), and in some examples, one or more of the units may be integrated circuits.
The video decoder 300 may include an ALU, an EFU, a digital circuit, an analog circuit, and/or a programmable core formed of programmable circuits. In examples where the operations of video decoder 300 are performed by software running on programmable circuits, on-chip or off-chip memory may store instructions (e.g., object code) of the software received and run by video decoder 300.
The entropy decoding unit 302 may receive encoded video data from the CPB and entropy decode the video data to reproduce syntax elements. The prediction processing unit 304, the inverse quantization unit 306, the inverse transform processing unit 308, the reconstruction unit 310, and the filter unit 312 may generate decoded video data based on syntax elements extracted from the bitstream.
Typically, video decoder 300 reconstructs the pictures on a block-by-block basis. The video decoder 300 may perform the reconstruction operation on each block separately (where the block currently being reconstructed (i.e., decoded) may be referred to as the "current block").
The entropy decoding unit 302 may entropy decode syntax elements defining quantized transform coefficients of the quantized transform coefficient block, as well as transform information, such as Quantization Parameter (QP) and/or transform mode indication(s). The inverse quantization unit 306 may determine a quantization degree using a QP associated with the quantized transform coefficient block and, as such, an inverse quantization degree for the inverse quantization unit 306 to apply. The inverse quantization unit 306 may, for example, perform a bitwise left shift operation to inversely quantize the quantized transform coefficients. The inverse quantization unit 306 may thus form a transform coefficient block including the transform coefficients.
After the inverse quantization unit 306 forms the transform coefficient block, the inverse transform processing unit 308 may apply one or more inverse transforms to the transform coefficient block to generate a residual block associated with the current block. For example, the inverse transform processing unit 308 may apply an inverse DCT, an inverse integer transform, an inverse Karhunen-Loeve transform (KLT), an inverse rotation transform, an inverse direction transform, or another inverse transform to the transform coefficient block.
Further, the prediction processing unit 304 generates a prediction block from the prediction information syntax element entropy-decoded by the entropy decoding unit 302. For example, if the prediction information syntax element indicates that the current block is inter predicted, the motion compensation unit 316 may generate the prediction block. In this case, the prediction information syntax element may indicate a reference picture in the DPB 314 from which the reference block is retrieved, and a motion vector identifying a position of the reference block in the reference picture relative to a position of the current block in the current picture. Motion compensation unit 316 may generally perform the inter-prediction process in a substantially similar manner as described with respect to motion compensation unit 224 (fig. 2).
As another example, if the prediction information syntax element indicates that the current block is intra-predicted, the intra-prediction unit 318 may generate the prediction block according to the intra-prediction mode indicated by the prediction information syntax element. Again, intra-prediction unit 318 may generally perform an intra-prediction process in a manner substantially similar to that described with respect to intra-prediction unit 226 (fig. 2). Intra-prediction unit 318 may retrieve data for neighboring samples of the current block from DPB 314.
The reconstruction unit 310 may reconstruct the current block using the prediction block and the residual block. For example, the reconstruction unit 310 may add samples of the residual block to corresponding samples of the prediction block to reconstruct the current block.
The LMCS unit 322 may be configured to perform luma mapping and chroma scaling. Additional details regarding the LMCS are discussed below with reference to fig. 4. In general, for luma data, LMCS unit 322 may perform in-loop mapping based on an adaptive piecewise linear model, and for chroma data, luma-related chroma residual scaling may be performed.
The filter unit 312 may perform one or more filtering operations on the reconstructed block. For example, the filter unit 312 may perform a deblocking operation to reduce blocking artifacts along edges of the reconstructed block. The operation of the filter unit 312 is not necessarily performed in all examples.
Video decoder 300 may store the reconstructed block in DPB 314. For example, in an example in which the operation of filter unit 312 is not performed, reconstruction unit 310 may store the reconstructed block to DPB 314. In an example of performing the operation of filter unit 312, filter unit 312 may store the filtered reconstructed block to DPB 314. As described above, DPB 314 may provide reference information to prediction processing unit 304, such as samples of the current picture for intra prediction and previously decoded pictures for subsequent motion compensation. Further, video decoder 300 may output the decoded pictures (e.g., decoded video) from DPB 314 for subsequent presentation on a display device, such as display device 118 of fig. 1.
Fig. 4 is a conceptual diagram illustrating an example architecture for performing Luma Mapping (LMCS) with chroma scaling. ITU-T h.266/universal video codec (VVC) includes Luma Mapping (LMCS) techniques with chroma scaling, which video codecs such as video encoder 200 and video decoder 300 may implement as separate processing blocks before loop filters, e.g., filter unit 216 (fig. 2) or filter unit 312 (fig. 3).
In the example of fig. 4, the architecture includes a chroma portion for decoding (i.e., reconstructing) the chroma data and a luma portion for decoding the luma data. The chroma portion includes a chroma scaling unit 150, a reconstruction unit 152, a loop filter unit 154, a DPB 156, an intra prediction unit 158, and a motion compensation unit 160. The luminance portion includes an inverse quantization and inverse transform unit 162, a reconstruction unit 164, an inverse shaping unit 176, a loop filter unit 166, a DPB 168, an intra prediction unit 170, a motion compensation unit 172, and a forward shaping unit 174.
According to VVC, LMCS has two main components: 1) An in-loop mapping of luminance components based on an adaptive piecewise linear model; 2) For the chrominance components, luminance-dependent chrominance residual scaling is applied. Fig. 4 illustrates an LMCS architecture from the perspective of a video decoder, such as video decoder 300. Thus, the video decoder 300 may also include an LMCS unit between the reconstruction unit 310 and the filter unit 312. As shown in the example of fig. 3, for example, video decoder 300 includes an LMCS unit 322, which may correspond to chroma scaling unit 150, inverse shaping unit 176, and forward shaping unit 174. Similarly, the video encoder 200 in the example of fig. 2 includes an LMCS unit 228, which may correspond to the chroma scaling unit 150, the inverse shaping unit 176, and the forward shaping unit 174 of fig. 4.
The inverse quantization and inverse transform (xform) unit 162 may correspond to the inverse quantization unit 210 and the inverse transform processing unit 212 (fig. 2) or the inverse quantization unit 306 and the inverse transform processing unit 308 (fig. 3). The reconstruction units 152 and 164 of fig. 4 may correspond to the reconstruction unit 214 (fig. 2) or the reconstruction unit 310 (fig. 3). The intra-prediction units 158, 170 of fig. 4 may correspond to the intra-prediction unit 226 (fig. 2) or the intra-prediction unit 318 (fig. 3). The inverse quantization and transform unit 162, the reconstruction unit 164, and the intra prediction unit 170 of fig. 4 may perform processing in the mapping domain.
The other units in fig. 4 may perform processing in the original (i.e., non-mapped) domain. Such units include loop filter units 154, 166 (e.g., deblocking, ALF, and SAO), motion compensation units 160, 172, chroma intra prediction unit 158, reconstruction unit 152, and DPBs 156, 168 that store the decoded pictures as reference pictures. The chroma scaling unit 150, forward shaping unit 174, and inverse shaping unit 176 of fig. 4 correspond to LMCS functional blocks. Like most other tools in VVCs, LMCS may be enabled/disabled at the sequence level using SPS flags.
The forward shaping unit 174 may perform in-loop mapping of the luminance component to adjust the dynamic range of the input signal, including reallocating codewords across the dynamic range to improve compression efficiency. The luminance mapping performed by the forward shaping unit 174 may utilize a forward mapping function FwdMap. The inverse shaping unit 176 may run a corresponding inverse mapping function InvMap.
As shown in fig. 4, motion compensated prediction is performed in the map domain for inter-coded blocks. In other words, motion compensated prediction block Y is calculated based on reference signals in the DPB pred Thereafter, the luminance prediction block in the original domain is mapped to the mapped domain Y 'by applying FwdMap function' pred =FwdMap(Y pred ). For intra-coded blocks, noThe FwdMap function is applied because intra prediction is performed in the map domain. In computing reconstructed block Y r Thereafter, the inverse shaping unit 176 may run an InvMap function to convert the reconstructed luminance values in the mapped domain back to the reconstructed luminance values in the original domainThe InvMap function may be applied to both intra-coded and inter-coded luma blocks.
Fig. 5A and 5B are conceptual diagrams illustrating examples of sub-blocks used in Overlapped Block Motion Compensation (OBMC). In particular, the example of fig. 5A depicts an example block (e.g., a current CU) that includes sub-blocks (i.e., blocks obscured with left-to-right down hashing) that apply OBMC at its CU or PU boundaries. In the example of fig. 5A, the motion vectors of sub-blocks 182B and 182B' are used to perform OBMC of sub-block 180B; and the motion vector of sub-block 182C is used to perform OBMC of sub-block 180C.
Fig. 5B depicts an example block (e.g., CU) including a sub-PU to which OBMC is applied in an Advanced Temporal Motion Vector Prediction (ATMVP) mode. In the example of fig. 5B, the motion vectors of neighboring sub-blocks 186A-186D (neighboring sub-blocks 186) are used to perform OBMC of sub-block 184.
In some examples, the OBMC may be turned on and off using syntax elements (e.g., flags) that are encoded and decoded at the CU level. When OBMC is used in a CU, OBMC may be performed on all Motion Compensation (MC) block boundaries except the right and bottom boundaries of the CU. Further, OBMC may be applied to both luminance and chrominance components. In some video codecs, MC blocks correspond to codec blocks. When a CU is encoded with sub-CU modes (e.g., including sub-CU merging, affine, and Frame Rate Up Conversion (FRUC) modes), each sub-block of the CU may be an MC block. To process CU boundaries in a unified manner, OBMC may be performed on all MC block boundaries at the sub-block level, where the sub-block size may be set equal to 4 x 4, as illustrated in fig. 5A and 5B.
When OBMC is applied to the current sub-block, in addition to the current motion vector, the motion vectors of four consecutive neighboring sub-blocks (if available and not identical to the current motion vector) may also be used to derive the prediction block of the current sub-block. These multiple prediction blocks based on multiple motion vectors may be combined to generate a final prediction signal for the current sub-block.
A prediction block based on a motion vector of a neighboring sub-block may be represented as P N Wherein N indicates indexes of adjacent upper, lower, left and right sub-blocks, and a prediction block based on a motion vector of a current sub-block is represented as P C . When P N Based on motion information of neighboring sub-blocks containing the same motion information as the current sub-block, may not be according to P N OBMC is performed. Otherwise, P N Can be added to P C The same spot in (i.e., P) N Is added to P C . Weighting factors {1/4,1/8, 1/16, 1/32} may be used for P N And weighting factors {3/4,7/8, 15/16, 31/32} may be used for P C . The exception is small MC blocks (e.g., when the height or width of the codec block is equal to 4 or the CU is coded with sub-CU mode), for small MC blocks, only P N Two rows/columns are added to P C . In this case, the weighting factor {1/4,1/8} is used for PN, and the weighting factor {3/4,7/8} may be used for P C . P for motion vector generation based on vertical (horizontal) neighboring sub-blocks N P can be set N Samples in the same row (column) of (a) are added to P with the same weighting factor C 。
In ITU-t h.266/universal video codec (VVC), CUs may be encoded using a combined inter/intra prediction (CIIP) mode. As its name indicates, CIIP prediction combines an inter prediction signal with an intra prediction signal to form a final prediction signal. The intra and inter prediction signals may be combined using a weighted average as follows:
P CIIP =(1-wt)*P inter +wt*P intra
As described above, the video codec performing the CIIP mode generates a final prediction value by calculating a weighted average of the inter prediction block and the intra prediction block. In the presence of LMCS, the inter-prediction values are in the original domain, while the intra-prediction values are in the mapped domain. Therefore, in VVC, luminance mapping is performed on inter-prediction values to map the inter-prediction values into a mapping domain before weighted averaging with intra-prediction values. When OBMC is applied to CIIP codec blocks, interactions with LMCS have not been defined.
The present disclosure describes various techniques for combining techniques of OBMC, LMCS, and CIIP. Although specific examples of OBMC, LMCS and CIIP are described, these techniques may also be applied to other codec techniques. For example, these techniques may be applied to OBMC variants using different on/off controls, weighting parameters, and/or other adaptation techniques. As another example, these techniques may be applied to LMCS variants using different mapping techniques. As yet another example, these techniques may be applied to CIIP variants using different weight calculation methods or other adaptation techniques. In general, the methods of the present disclosure are applicable to a codec tool that uses at least one intra-prediction value and one inter-prediction value that uses motion information from neighboring decoded blocks.
In some examples, the CIIP flag may be signaled in the bitstream before the OBMC flag. In one example, OBMC is disabled for CIIP. In particular, when a video codec (such as video encoder 200 or video decoder 300) determines that the current block is encoded using CIIP mode, the video codec does not encode the OBMC flag and deduces that the OBMC flag is false (i.e., no OBMC is used). In some examples, if LMCS is applied, the video codec disables OBMC of the CIIP codec block. When LMCS is applied and the current block uses CIIP mode, the video codec does not codec the OBMC flag and deduces that the OBMC flag is false.
In some examples, the video codec encodes a CU level flag indicating that LMCS is used for the current block, where the LMCS CU level flag is encoded after the CIIP and OBMC flags. When both OBMC and CIIP are applied to the current block, the video codec may infer that the LMCS CU level flag is false without explicitly coding the LMCS CU level flag, whether or not the CIIP flag is indicated before the OBMC flag.
In some examples, the OBMC flag may be signaled in the bitstream before the CIIP flag. In one example, the video encoder disables the CIIP mode of the OBMC. Specifically, when the current block is encoded using the OBMC mode, the video codec does not encode the value of the CIIP flag and deduces that the CIIP flag is false. In some examples, if LMCS is applied, the video codec disables CIIP for the OBMC-coded blocks. When LMCS is applied and the current block is encoded using OBMC mode, the video codec may not encode the CIIP flag and infer that the CIIP flag is false.
Fig. 6 is a flowchart illustrating an example method for encoding a current block in accordance with the techniques of this disclosure. The current block may include the current CU. Although described with respect to video encoder 200 (fig. 1 and 2), it should be understood that other devices may also be configured to perform a method similar to fig. 6.
In this example, video encoder 200 first predicts the current block (350). For example, the video encoder 200 may form a prediction block of the current block. Video encoder 200 may predict the block using any of the various techniques of the present disclosure, for example, using various combinations of OBMC, CIIP, and/or LMCS, such as the techniques discussed above or described below with reference to fig. 8-10. In particular, the video encoder 200 may generate an inter prediction block and an intra prediction block of the current block. The video encoder 200 may then generate a final prediction block from the inter prediction block and the intra prediction block, including performing a combination of OBMC, CIIP, and LMCS when generating the final prediction block.
The video encoder 200 may then calculate a residual block for the current block (352). To calculate the residual block, the video encoder 200 may calculate the difference between the original, non-decoded block and the prediction block (i.e., the final prediction block) of the current block. The video encoder 200 may then transform the residual block and quantize the transform coefficients of the residual block (354). Next, video encoder 200 may scan the quantized transform coefficients of the residual block (356). During or after scanning, the video encoder 200 may entropy encode the transform coefficients (358). For example, the video encoder 200 may encode transform coefficients using CAVLC or CABAC. The video encoder 200 may then output entropy encoded data of the block (360).
The video encoder 200 may also decode the current block after encoding the current block to use the decoded version of the current block as reference data for subsequently decoded data (e.g., in inter or intra prediction mode). Accordingly, the video encoder 200 may inverse quantize and inverse transform the coefficients to reproduce the residual block (362). The video encoder 200 may combine the residual block with the prediction block to form a decoded block (364). Video encoder 200 may then store the decoded blocks in DPB 218 (366).
In this way, the method of fig. 6 represents an example of a method of encoding and decoding video data, including generating an inter-prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Fig. 7 is a flowchart illustrating an example method for decoding a current block of video data in accordance with the techniques of this disclosure. The current block may include the current CU. Although described with respect to video decoder 300 (fig. 1 and 3), it should be understood that other devices may be configured to perform a method similar to fig. 7.
The video decoder 300 may receive entropy-encoded data of the current block, such as entropy-encoded data of transform coefficients of a residual block corresponding to the current block and entropy-encoded prediction information (370). The video decoder 300 may entropy decode the entropy encoded data to determine prediction information of the current block and reproduce transform coefficients of the residual block (372). The video decoder 300 may predict the current block (374) (e.g., using intra or inter prediction modes indicated by the prediction information of the current block) to calculate a predicted block of the current block. The video decoder 300 may predict the block using any of the various techniques of the present disclosure, for example, using various combinations of OBMC, CIIP, and/or LMCS, such as the techniques discussed above or described below with reference to fig. 8-10. In particular, the video decoder 300 may generate an inter prediction block and an intra prediction block of the current block. The video decoder 300 may then generate a final prediction block from the inter prediction block and the intra prediction block, including performing a combination of OBMC, CIIP, and LMCS when generating the final prediction block.
The video decoder 300 may then inverse scan the reproduced transform coefficients (376) to create blocks of quantized transform coefficients. Video decoder 300 may then inverse quantize the transform coefficients and apply an inverse transform to the transform coefficients to generate a residual block (378). The video decoder 300 may eventually decode the current block by combining the prediction block and the residual block (380).
In this way, the methods of fig. 6 and 7 represent examples of a method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; in response to determining that the current block is encoded using the CIIP mode, preventing encoding and decoding of Overlapped Block Motion Compensation (OBMC) information of the current block; and decoding the current block using the CIIP mode.
The methods of fig. 6 and 7 also represent examples of a method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode and using Overlapped Block Motion Compensation (OBMC), the current block comprising at least a portion of a Coding Unit (CU) of the video data; in response to determining that the current block is encoded using the CIIP mode and the OBMC, determining not to apply a Luma Map (LMCS) with chroma scaling to the current block; and decoding the current block using the CIIP mode and the OBMC without applying the LMCS to the current block.
The methods of fig. 6 and 7 also represent examples of a method comprising: determining that a current block of video data is encoded using Overlapped Block Motion Compensation (OBMC); in response to determining that the current block is encoded using OBMC, preventing encoding and decoding of combined inter/intra prediction (CIIP) mode information for the current block; and decoding the current block using the OBMC mode.
The methods of fig. 6 and 7 also represent examples of a method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; generating an inter prediction block of the current block using Overlapped Block Motion Compensation (OBMC); generating an intra prediction block of the current block; generating a prediction block of the current block using the inter prediction block and the intra prediction block; and decoding the current block using the predicted block (e.g., including the method of fig. 8 discussed in more detail below).
The methods of fig. 6 and 7 also represent examples of a method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); generating an inter prediction block of the current block using motion information of the current block; performing luminance mapping on the inter-frame prediction block according to the LMCS to form a final inter-frame prediction block of the current block; generating an intra prediction block of the current block; performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; generating one or more other inter prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; performing luminance mapping on one or more other intermediate prediction blocks according to the LMCS to form one or more other prediction blocks of the current block; generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and decoding the current block using the final predicted block (e.g., including the method of fig. 9 discussed in more detail below).
The methods of fig. 6 and 7 also represent examples of a method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); generating an inter prediction block of the current block using motion information of the current block; performing luminance mapping on the inter-frame prediction block according to the LMCS to form a final inter-frame prediction block of the current block; generating an intra prediction block of the current block; performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; generating one or more other prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and decoding the current block using the final predicted block (e.g., including the method of fig. 10 discussed in more detail below).
The method of fig. 7 also represents an example of a method of decoding video data, the method comprising: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Fig. 8 is a flowchart illustrating an example method of jointly predicting blocks of video data using OBMC and CIIP. The video encoder 200 or the video decoder 300 may be configured to perform the method when predicting blocks of video data. The method of fig. 8 is specifically discussed with respect to video decoder 300, but it should be understood that video encoder 200 may perform this or a similar method. The method of fig. 8 may be performed during prediction of a block of video data, for example, during step 350 of the method of fig. 6 or step 374 of the method of fig. 7.
In this example, the video decoder 300 may initially generate an inter prediction block using motion information of a current block of video data (400). The video decoder 300 may then apply the OBMC to the inter prediction block to generate an OBMC inter prediction block (402). The video decoder 300 may then perform luma mapping with chroma scaling (LMCS) on the OBMC inter prediction blocks to form LMCS inter prediction blocks (404). The video decoder 300 may also generate an intra prediction block (406). The video decoder 300 may perform CIIP to combine the LMCS inter prediction block and the intra prediction block (408).
In other words, the video decoder 300 may generate the final prediction block as the CIIP block (i.e., the inter prediction block of the CIIP block is updated with the OBMC), and then the video decoder 300 may apply a luminance map (if LMCS exists) to the luminance inter prediction block updated with the OBMC before performing the weighted average with the intra prediction block.
In this way, the method of fig. 8 represents an example of a method of decoding or encoding a block of video data, the method comprising: performing OBMC on the inter-prediction block to form an OBMC-compensated inter-prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Fig. 9 is a flowchart illustrating an example method of jointly predicting blocks of video data using CIIP, OBMC, and LMCS. The video encoder 200 or the video decoder 300 may be configured to perform the method when predicting blocks of video data. The method of fig. 9 is specifically discussed with respect to video decoder 300, but it should be understood that video encoder 200 may perform this or a similar method. The method of fig. 9 may be performed during prediction of a block of video data, for example, during step 350 of the method of fig. 6 or step 374 of the method of fig. 7.
In the example of fig. 9, the video decoder 300 applies a hybrid process of OBMC on top of the combined inter and intra prediction signals of CIIP. In general, the video decoder 300 first generates a combined inter and intra prediction signal, denoted as P, using motion information and intra prediction information of a current block C . That is, the video decoder 300 first generates an inter prediction block using motion information of the current block (410). The video decoder 300 then performs luma mapping with chroma scaling on the inter prediction block (412). The video decoder 300 also generates an intra prediction block (414). The video decoder 300 performs CIIP to combine LMCS inter prediction blocks and intra prediction blocks (416), where the CIIP combined blocks are referred to as P C 。
The video decoder 300 then generates one or more other prediction blocks, denoted P, based on the motion information of the neighboring sub-blocks (418) N . If an LMCS is present, the video decoder 300 may then apply the luminance map to the predictionBlock P N (420). Finally, the video decoder 300 may perform an OBMC mixing process to combine P N And P C (422)。
In this manner, the method of fig. 9 represents an example method for decoding or encoding video data, the method comprising: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; performing LMCS on the second inter-predictor block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Fig. 10 is a flowchart illustrating another example method of jointly predicting blocks of video data using CIIP, OBMC, and LMCS. The video encoder 200 or the video decoder 300 may be configured to perform the method when predicting blocks of video data. The method of fig. 10 is specifically discussed with respect to video decoder 300, but it should be understood that video encoder 200 may perform this or a similar method. The method of fig. 10 may be performed during prediction of a block of video data, for example, during step 350 of the method of fig. 6 or step 374 of the method of fig. 7.
Generally, in the example of fig. 10, as in the example of fig. 9, the video decoder 300 applies a mixing process of OBMC on top of the combined inter and intra prediction signals. However, in this example, the luminance mapping is not performed on top of the prediction block generated using the motion information of the neighboring blocks.
Specifically, in the example of fig. 10, the video decoder 300 first generates an inter prediction block using motion information of the current block (430). The video decoder 300 then performs luma mapping with chroma scaling on the inter prediction block (432). The video decoder 300 also generates an intra prediction block (434). The video decoder 300 performs CIIP to combine LMCS inter prediction blocks and intra prediction blocks (436), where the CIIP combined blocks are referred to as P C 。
The video decoder 300 then generates one or more other prediction blocks based on the motion information of the neighboring sub-blocks (438), denoted asP N . Finally, the video decoder 300 may perform an OBMC mixing process to combine P N And P C (440)。
In this manner, the method of fig. 10 represents an example method for decoding or encoding video data, the method comprising: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
The following clauses represent certain example techniques of the present disclosure:
clause 1: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; in response to determining that the current block is encoded using CIIP mode, preventing encoding and decoding of Overlapped Block Motion Compensation (OBMC) information for the current block; and decoding the current block using the CIIP mode.
Clause 2: the method of clause 1, further comprising inferring that the OBMC is not applied to the current block, and wherein decoding the current block comprises decoding the current block without performing the OBMC.
Clause 3: the method of any of clauses 1 and 2, further comprising determining that a Luma Map (LMCS) with chroma scaling is to be applied to the current block, wherein determining that the OBMC information is not signaled comprises determining that the OBMC information is not signaled in response to determining that the current block is encoded using the CIIP mode and that the LMCS is not applied to the current block.
Clause 4: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode and using Overlapped Block Motion Compensation (OBMC), the current block comprising at least a portion of a Coding Unit (CU) of the video data; in response to determining that the current block is encoded using the CIIP mode and the OBMC, determining not to apply a Luma Map (LMCS) with chroma scaling to the current block; and decoding the current block using the CIIP mode and the OBMC without applying the LMCS to the current block.
Clause 5: the method of clause 4, wherein determining not to apply the LMCS to the current block comprises determining that no LMCS flag is signaled in the CU and inferring that the value of the LMCS flag is false, the LMCS flag indicating whether to apply the LMCS to the block of the CU.
Clause 6: the method according to any one of clauses 4 and 5, further comprising: encoding and decoding a CIIP flag having a value indicating that a CIIP mode is to be applied to a current block; and encoding and decoding the OBMC flag, the OBMC flag having a value indicating that the OBMC is to be applied to the current block.
Clause 7: the method according to any of clauses 4-6, further comprising avoiding coding any LMCS information of the current block.
Clause 8: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using Overlapped Block Motion Compensation (OBMC); in response to determining that the current block is encoded using OBMC, preventing encoding and decoding of combined inter/intra prediction (CIIP) mode information for the current block; and decoding the current block using the OBMC mode.
Clause 9: the method of clause 8, further comprising inferring that the CIIP mode is not applied to the current block, and wherein decoding the current block includes decoding the current block without performing the CIIP mode.
Clause 10: the method of any of clauses 8 and 9, further comprising determining that a Luma Map (LMCS) with chroma scaling is to be applied to the current block, wherein determining that the CIIP mode information is not signaled comprises determining that the CIIP mode information is not signaled in response to determining that the current block is encoded using OBMC and that the LMCS is to be applied to the current block.
Clause 11: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; generating an inter prediction block of the current block using Overlapped Block Motion Compensation (OBMC); generating an intra prediction block of the current block; generating a prediction block of the current block using the inter prediction block and the intra prediction block; and decoding the current block using the prediction block.
Clause 12: the method of clause 11, wherein the inter-predicted block comprises an inter-predicted block, the method further comprising performing luma mapping on the inter-predicted block according to a luma map with chroma scaling (LMCS) to form a final inter-predicted block, and wherein generating the predicted block comprises generating the predicted block using the final inter-predicted block and the intra-predicted block.
Clause 13: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); generating an inter prediction block of the current block using motion information of the current block; performing luminance mapping on the inter-frame prediction block according to the LMCS to form a final inter-frame prediction block of the current block; generating an intra prediction block of the current block; performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; generating one or more other inter prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; performing luminance mapping on one or more other intermediate prediction blocks according to the LMCS to form one or more other prediction blocks of the current block; generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and decoding the current block using the final prediction block.
Clause 14: a method of decoding video data, the method comprising: determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); generating an inter prediction block of the current block using motion information of the current block; performing luminance mapping on the inter-frame prediction block according to the LMCS to form a final inter-frame prediction block of the current block; generating an intra prediction block of the current block; performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; generating one or more other prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and decoding the current block using the final prediction block.
Clause 15: the method according to any of clauses 1-14, further comprising encoding the current block prior to decoding the current block.
Clause 16: an apparatus for decoding video data, the apparatus comprising one or more components for performing the method of any of clauses 1-15.
Clause 17: the apparatus of clause 16, wherein the one or more components comprise one or more processors implemented in circuitry.
Clause 18: the apparatus of any of clauses 16 and 17, further comprising a display configured to display the decoded video data.
Clause 19: the device of clauses 16-18, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set top box.
Clause 20: the apparatus of clauses 16-19, further comprising a memory configured to store video data.
Clause 21: a computer readable storage medium having instructions stored thereon that, when executed, cause a processor of an apparatus for decoding video data to perform the method of any of clauses 1-15.
Clause 22: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; means for preventing, in response to determining that the current block is encoded using the CIIP mode, encoding and decoding of Overlapped Block Motion Compensation (OBMC) information of the current block; and decoding the current block using the CIIP mode.
Clause 23: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode and using Overlapped Block Motion Compensation (OBMC), the current block comprising at least a portion of a Coding Unit (CU) of the video data; means for determining not to apply a Luma Map (LMCS) with chroma scaling to the current block in response to determining that the current block is encoded using the CIIP mode and the OBMC; and means for decoding the current block using the CIIP mode and the OBMC without applying LMCS to the current block.
Clause 24: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using Overlapped Block Motion Compensation (OBMC); means for preventing, in response to determining that the current block is encoded using OBMC, encoding and decoding of combined inter/intra prediction (CIIP) mode information for the current block; and means for decoding the current block using the OBMC mode.
Clause 25: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode; means for generating an inter prediction block of the current block using Overlapped Block Motion Compensation (OBMC); means for generating an intra-predicted block of the current block; means for generating a prediction block of the current block using the inter prediction block and the intra prediction block; and means for decoding the current block using the prediction block.
Clause 26: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); means for generating an inter prediction block of the current block using motion information of the current block; means for performing luminance mapping on the inter prediction block according to the LMCS to form a final inter prediction block of the current block; means for generating an intra-predicted block of the current block; means for performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; means for generating one or more other inter prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; means for performing luma mapping on one or more other inter-predicted blocks in accordance with the LMCS to form one or more other predicted blocks of the current block; means for generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and means for decoding the current block using the final prediction block.
Clause 27: an apparatus for decoding video data, the apparatus comprising: means for determining that a current block of video data is encoded using a combined inter/intra prediction (CIIP) mode, overlapped Block Motion Compensation (OBMC), and luma map with chroma scaling (LMCS); means for generating an inter prediction block of the current block using motion information of the current block; means for performing luminance mapping on the inter prediction block according to the LMCS to form a final inter prediction block of the current block; means for generating an intra-predicted block of the current block; means for performing CIIP to combine the final inter prediction block with the intra prediction block to form a first prediction block of the current block; means for generating one or more other prediction blocks of the current block using motion information of one or more blocks adjacent to the current block; means for generating a final prediction block of the current block using the first prediction block and the one or more other prediction blocks according to the OBMC; and means for decoding the current block using the final prediction block.
Clause 28: a method for decoding video data, the method comprising: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 29: the method of clause 28, wherein generating the final prediction block of the current block of video data comprises: performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 30: the method of clause 28, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, the method further comprising generating a second inter-predicted sub-block of the current block, wherein generating the final predicted block of the current block of video data comprises: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 31: the method of clause 30, further comprising performing LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 32: the method of clause 28, wherein the inter-predicted block comprises a first inter-predicted sub-block of a current block of video data, the method further comprising: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein generating a final predictor block for the current block of video data comprises: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 33: the method according to clause 28, further comprising: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 34: the method of clause 33, wherein encoding the CIIP syntax element comprises encoding the CIIP syntax element after encoding the OBMC syntax element.
Clause 35: the method of clause 28, further comprising encoding the current block prior to decoding the current block.
Clause 36: an apparatus for decoding video data, the apparatus comprising: a memory configured to store video data; and one or more processors implemented in the circuitry and configured to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 37: the apparatus of clause 36, wherein to generate the final predicted block of the current block of video data, the one or more processors are configured to: performing OBMC on the inter-prediction block to form an OBMC-compensated inter-prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 38: the apparatus of clause 36, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, wherein the one or more processors are further configured to generate a second inter-predicted sub-block of the current block, wherein to generate a final predicted block of the current block of video data, the one or more processors are configured to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 39: the apparatus of clause 38, wherein the one or more processors are further configured to perform LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 40: the apparatus of clause 36, wherein the inter-predicted block comprises a first inter-predicted sub-block of a current block of video data, and wherein the one or more processors are further configured to: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein to generate a final predicted block for the current block of video data, the one or more processors are configured to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 41: the apparatus of clause 36, wherein the one or more processors are further configured to: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 42: the apparatus of clause 41, wherein the one or more processors are configured to encode the CIIP syntax element after encoding the OBMC syntax element.
Clause 43: the apparatus of clause 36, wherein the one or more processors are further configured to encode the current block prior to decoding the current block.
Clause 44: the apparatus of clause 36, further comprising a display configured to display the decoded video data.
Clause 45: the device of clause 36, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.
Clause 46: a computer-readable storage medium having instructions stored thereon that, when executed, cause a processor of an apparatus for decoding video data to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 47: the computer-readable storage medium of clause 46, wherein the instructions that cause the processor to generate the final predicted block of the current block of video data comprise instructions that cause the processor to: performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 48: the computer-readable storage medium of clause 46, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, further comprising instructions that cause the processor to generate a second inter-predicted sub-block of the current block, wherein the instructions that cause the processor to generate a final predicted block of the current block of video data comprise instructions that cause the processor to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 49: the computer-readable storage medium of clause 48, further comprising instructions that cause the processor to perform LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 50: the computer-readable storage medium of clause 46, wherein the inter-predicted block comprises a first inter-predicted sub-block of a current block of video data, further comprising instructions that cause the processor to: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein the instructions that cause the processor to generate a final predicted block for the current block of video data comprise instructions that cause the processor to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 51: the computer-readable storage medium of clause 46, further comprising instructions that cause the processor to: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 52: the computer readable storage medium of clause 51, wherein the instructions that cause the processor to codec the CIIP syntax element comprise instructions that cause the processor to codec the CIIP syntax element after the OBMC syntax element is encoded.
Clause 53: the computer-readable storage medium of clause 46, further comprising instructions that cause the processor to encode the current block prior to decoding the current block.
Clause 54: an apparatus for decoding video data, the apparatus comprising: means for generating an inter prediction block of a current block of video data; means for generating an intra-predicted block of a current block of video data; means for generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and means for decoding a current block of video data using the final prediction block.
Clause 55: the apparatus of clause 54, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, further comprising means for generating a second inter-predicted sub-block of the current block, wherein the final predicted block means for generating the current block of video data comprises: means for performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and means for performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 56: a method for decoding video data, the method comprising: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 57: the method of clause 56, wherein generating the final prediction block of the current block of video data comprises: performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 58: the method of clause 56, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, the method further comprising generating a second inter-predicted sub-block of the current block, wherein generating the final predicted block of the current block of video data comprises: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 59: the method of clause 58, further comprising performing LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 60: the method of clause 56, wherein the inter-predicted block comprises a first inter-predicted sub-block of a current block of video data, the method further comprising: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein generating a final predictor block for the current block of video data comprises: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 61: the method according to any of clauses 56-60, further comprising: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 62: the method of clause 61, wherein encoding the CIIP syntax element comprises encoding the CIIP syntax element after encoding the OBMC syntax element.
Clause 63: the method according to any of clauses 56-62, further comprising encoding the current block prior to decoding the current block.
Clause 64: an apparatus for decoding video data, the apparatus comprising: a memory configured to store video data; and one or more processors implemented in the circuitry and configured to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 65: the apparatus of clause 64, wherein to generate the final predicted block of the current block of video data, the one or more processors are configured to: performing OBMC on the inter-prediction block to form an OBMC-compensated inter-prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 66: the apparatus of clause 64, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, wherein the one or more processors are further configured to generate a second inter-predicted sub-block of the current block, wherein to generate a final predicted block of the current block of video data, the one or more processors are configured to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 67: the apparatus of clause 66, wherein the one or more processors are further configured to perform LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 68: the apparatus of clause 64, wherein the inter-predicted block comprises a first inter-predicted sub-block of a current block of video data, and wherein the one or more processors are further configured to: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein to generate a final predicted block for the current block of video data, the one or more processors are configured to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 69: the apparatus according to any of clauses 64-68, wherein the one or more processors are further configured to: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 70: the apparatus of clause 69, wherein the one or more processors are configured to encode the CIIP syntax element after encoding the OBMC syntax element.
Clause 71: the apparatus of any of clauses 64-70, wherein the one or more processors are further configured to encode the current block prior to decoding the current block.
Clause 72: the apparatus of any of clauses 64-71, further comprising a display configured to display the decoded video data.
Clause 73: the device of clauses 64-72, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set top box.
Clause 74: a computer-readable storage medium having instructions stored thereon that, when executed, cause a processor of an apparatus for decoding video data to: generating an inter prediction block of a current block of video data; generating an intra-prediction block of a current block of video data; generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and decoding a current block of video data using the final prediction block.
Clause 75: the computer-readable storage medium of clause 74, wherein the instructions that cause the processor to generate the final predicted block of the current block of video data comprise instructions that cause the processor to: performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block; performing LMCS on the OBMC-compensated inter prediction blocks to form LMCS-mapped inter prediction blocks; and combining the LMCS mapped inter prediction block with the intra prediction block using the CIIP mode to generate a final prediction block.
Clause 76: the computer-readable storage medium of clause 74, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, further comprising instructions that cause the processor to generate a second inter-predicted sub-block of the current block, wherein the instructions that cause the processor to generate a final predicted block of the current block of video data comprise instructions that cause the processor to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
Clause 77: the computer-readable storage medium of clause 76, further comprising instructions that cause the processor to perform LMCS on the second inter-predictor block prior to performing OBMC blending.
Clause 78: the computer-readable storage medium of clause 74, wherein the inter-prediction block comprises a first inter-prediction sub-block of a current block of video data, further comprising instructions that cause the processor to: generating a second inter-predictor block for the current block; and performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block, wherein the instructions that cause the processor to generate a final predicted block for the current block of video data comprise instructions that cause the processor to: performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and performing OBMC blending between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate a final predictor block.
Clause 79: the computer-readable storage medium according to any of clauses 74-78, further comprising instructions to cause the processor to: an OBMC syntax element encoding and decoding the current block, the syntax element indicating that the current block is to be predicted using OBMC; coding a CIIP syntax element of the current block, the syntax element indicating that the current block is to be predicted using CIIP; and encoding an LMCS syntax element of the current block, the syntax element indicating that the current block is to be predicted using the LMCS.
Clause 80: the computer readable storage medium of clause 79, wherein the instructions that cause the processor to codec the CIIP syntax element comprise instructions that cause the processor to codec the CIIP syntax element after the OBMC syntax element is encoded.
Clause 81: the computer-readable storage medium of any of clauses 74-80, further comprising instructions to cause the processor to encode the current block prior to decoding the current block.
Clause 82: an apparatus for decoding video data, the apparatus comprising: means for generating an inter prediction block of a current block of video data; means for generating an intra-predicted block of a current block of video data; means for generating a final prediction block of a current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and means for decoding a current block of video data using the final prediction block.
Clause 83: the apparatus of clause 82, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, further comprising means for generating a second inter-predicted sub-block of the current block, wherein the final predicted block means for generating the current block of video data comprises: means for performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block; combining the LMCS mapped first inter-prediction sub-block with the intra-prediction block using the CIIP mode to generate a first CIIP-prediction sub-block of the current block; and means for performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate a final predictor block.
It should be appreciated that certain acts or events of any of the techniques described herein can be performed in a different order, may be added, combined, or omitted entirely, depending on the example (e.g., not all of the described acts or events are necessary for the practice of the technique). Further, in some examples, acts or events may be performed concurrently (e.g., through multi-threaded processing, interrupt processing, or multiple processors) rather than sequentially.
In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium, such as a data storage medium, or a communication medium including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, a computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for use in implementing the techniques described in this disclosure. The computer program product may include a computer-readable medium.
By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Further, any connection is properly termed a computer-readable medium. For example, if the instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
The instructions may be executed by one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Thus, the terms "processor" and "processing circuitry" as used herein may refer to any of the foregoing structures or any other structure suitable for implementation of the techniques described herein. Furthermore, in some aspects, the functionality described herein may be provided in dedicated hardware and/or software modules configured for encoding and decoding, or incorporated in a combined codec. Moreover, the techniques may be implemented entirely in one or more circuits or logic elements.
The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses including a wireless handset, an Integrated Circuit (IC), or a group of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques but do not necessarily require realization by different hardware units. Rather, as described above, the various units may be combined in a codec hardware unit or provided by a collection of interoperable hardware units including one or more processors as described above in combination with appropriate software and/or firmware.
Various examples have been described. These and other examples are within the scope of the following claims.
Claims (28)
1. A method of decoding video data, the method comprising:
generating an inter prediction block of a current block of video data;
generating an intra-prediction block of the current block of video data;
generating a final prediction block of the current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and
the current block of video data is decoded using the final prediction block.
2. The method of claim 1, wherein generating the final prediction block of the current block of video data comprises:
performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block;
performing LMCS on the OBMC-compensated inter prediction block to form an LMCS mapped inter prediction block; and
the LMCS mapped inter prediction block is combined with the intra prediction block using CIIP mode to generate the final prediction block.
3. The method of claim 1, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, the method further comprising generating a second inter-predicted sub-block of the current block, wherein generating the final predicted block of the current block of video data comprises:
performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the second inter predictor block to generate the final predictor block.
4. The method of claim 3, further comprising performing LMCS on the second inter-predictor block prior to performing the OBMC blending.
5. The method of claim 1, wherein the inter-prediction block comprises a first inter-predictor block of the current block of video data, the method further comprising:
generating a second inter-predictor block for the current block; and
performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block;
Wherein generating the final prediction block of the current block of video data comprises:
performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate the final predictor block.
6. The method of claim 1, further comprising:
encoding an OBMC syntax element of the current block, the OBMC syntax element indicating that the current block is to be predicted using OBMC;
coding a CIIP syntax element of the current block, the CIIP syntax element indicating that the current block is to be predicted using CIIP; and
an LMCS syntax element of the current block is encoded, the LMCS syntax element indicating that the current block is to be predicted using LMCS.
7. The method of claim 6, wherein encoding the CIIP syntax element comprises encoding the CIIP syntax element after encoding the OBMC syntax element.
8. The method of claim 1, further comprising encoding the current block prior to decoding the current block.
9. An apparatus for decoding video data, the apparatus comprising:
a memory configured to store video data; and
one or more processors implemented in circuitry, the one or more processors configured to:
generating an inter prediction block of a current block of video data;
generating an intra-prediction block of the current block of video data;
generating a final prediction block of the current block of the video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) when generating the final prediction block; and
the current block of the video data is decoded using the final prediction block.
10. The apparatus of claim 9, wherein to generate the final predicted block of the current block of video data, the one or more processors are configured to:
performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block;
performing LMCS on the OBMC-compensated inter prediction block to form an LMCS mapped inter prediction block; and
The LMCS mapped inter prediction block is combined with the intra prediction block using CIIP mode to generate the final prediction block.
11. The apparatus of claim 9, wherein the inter-predicted block comprises a first inter-predicted sub-block of the current block of video data, wherein the one or more processors are further configured to generate a second inter-predicted sub-block of the current block, wherein to generate the final predicted block of the current block of video data, the one or more processors are configured to:
performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the second inter predictor block to generate the final predictor block.
12. The apparatus of claim 11, wherein the one or more processors are further configured to perform LMCS on the second inter-predictor block prior to performing the OBMC mixing.
13. The apparatus of claim 9, wherein the inter-prediction block comprises a first inter-prediction sub-block of the current block of video data, and wherein the one or more processors are further configured to:
generating a second inter-predictor block for the current block; and
performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block;
wherein to generate the final predicted block of the current block of video data, the one or more processors are configured to:
performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate the final predictor block.
14. The device of claim 9, wherein the one or more processors are further configured to:
encoding an OBMC syntax element of the current block, the OBMC syntax element indicating that the current block is to be predicted using OBMC;
Coding a CIIP syntax element of the current block, the CIIP syntax element indicating that the current block is to be predicted using CIIP; and
an LMCS syntax element of the current block is encoded, the LMCS syntax element indicating that the current block is to be predicted using LMCS.
15. The device of claim 14, wherein one or more processors are configured to encode the CIIP syntax element after encoding the OBMC syntax element.
16. The apparatus of claim 9, wherein the one or more processors are further configured to encode the current block prior to decoding the current block.
17. The device of claim 9, further comprising a display configured to display the decoded video data.
18. The device of claim 9, wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set top box.
19. A computer-readable storage medium having instructions stored thereon that, when executed, cause a processor of an apparatus for decoding video data to:
generating an inter prediction block of a current block of video data;
generating an intra-prediction block of the current block of video data;
Generating a final prediction block of the current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and
the current block of video data is decoded using the final prediction block.
20. The computer-readable storage medium of claim 19, wherein the instructions that cause the processor to generate the final predicted block of the current block of video data comprise instructions that cause the processor to:
performing OBMC on the inter prediction block to form an OBMC-compensated inter prediction block;
performing LMCS on the OBMC-compensated inter prediction block to form an LMCS mapped inter prediction block; and
the LMCS mapped inter prediction block is combined with the intra prediction block using CIIP mode to generate the final prediction block.
21. The computer-readable storage medium of claim 19, wherein the inter-prediction block comprises a first inter-prediction sub-block of the current block of the video data, further comprising instructions that cause the processor to generate a second inter-prediction sub-block of the current block, wherein the instructions that cause the processor to generate the final prediction block of the current block of video data comprise instructions that cause the processor to:
Performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the second inter predictor block to generate the final predictor block.
22. The computer-readable storage medium of claim 21, further comprising instructions that cause the processor to perform LMCS on the second inter-predictor block prior to performing the OBMC blending.
23. The computer-readable storage medium of claim 19, wherein the inter-prediction block comprises a first inter-prediction sub-block of the current block of video data, further comprising instructions that cause the processor to:
generating a second inter-predictor block for the current block; and
performing LMCS on the second inter-predictor block to form an LMCS mapped second inter-predictor block;
wherein the instructions that cause the processor to generate the final predicted block of the current block of video data comprise instructions that cause the processor to:
Performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
an OBMC blend is performed between the first CIIP predictor block and the LMCS mapped second inter predictor block to generate the final predictor block.
24. The computer-readable storage medium of claim 19, further comprising instructions that cause the processor to:
encoding an OBMC syntax element of the current block, the OBMC syntax element indicating that the current block is to be predicted using OBMC;
coding a CIIP syntax element of the current block, the CIIP syntax element indicating that the current block is to be predicted using CIIP; and
an LMCS syntax element of the current block is encoded, the LMCS syntax element indicating that the current block is to be predicted using LMCS.
25. The computer-readable storage medium of claim 24, wherein the instructions that cause the processor to codec the CIIP syntax element comprise instructions that cause the processor to codec the CIIP syntax element after encoding the OBMC syntax element.
26. The computer-readable storage medium of claim 19, further comprising instructions that cause the processor to encode the current block prior to decoding the current block.
27. An apparatus for decoding video data, the apparatus comprising:
means for generating an inter prediction block of a current block of video data;
means for generating an intra-predicted block of the current block of video data;
means for generating a final prediction block of the current block of video data from the inter prediction block and the intra prediction block, including performing each of a combined inter/intra prediction (CIIP) mode, an Overlapped Block Motion Compensation (OBMC), and a luma map with chroma scaling (LMCS) in generating the final prediction block; and
means for decoding the current block of video data using the final prediction block.
28. The apparatus of claim 27, wherein the inter-prediction block comprises a first inter-prediction sub-block of the current block of video data, further comprising means for generating a second inter-prediction sub-block of the current block, wherein means for generating the final prediction block of the current block of video data comprises:
Means for performing LMCS on the first inter-predictor block to form an LMCS mapped first inter-predictor block;
means for combining the LMCS mapped first inter-predictor block with the intra-predictor block using a CIIP mode to generate a first CIIP predictor block for the current block; and
means for performing OBMC blending between the first CIIP predictor block and the second inter predictor block to generate the final predictor block.
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US63/197,190 | 2021-06-04 | ||
US17/662,140 | 2022-05-05 | ||
US17/662,140 US11924410B2 (en) | 2021-06-04 | 2022-05-05 | Video coding using overlapped block motion compensation, combined inter-intra prediction, and/or luma mapping and chroma scaling |
PCT/US2022/072165 WO2022256762A1 (en) | 2021-06-04 | 2022-05-06 | Video coding using overlapped block motion compensation, combined inter-intra prediction, and/or luma mapping and chroma scaling |
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