WO2012167927A1

WO2012167927A1 - Coding of control data for adaptive loop filters

Info

Publication number: WO2012167927A1
Application number: PCT/EP2012/002413
Authority: WO
Inventors: Matthias Narroschke; Semith ESSENLIK; Virginie Drugeon; Thomas Wedi; Anand KOTRA
Original assignee: Panasonic Corporation
Priority date: 2011-06-09
Filing date: 2012-06-06
Publication date: 2012-12-13

Abstract

The present invention relates to bitstream organization, coding and decoding of the image data including filtering parameters. In particular, according to the present invention the slices of images and the filtering parameters relating to filtering of the respective slices are encoded and decoded independently of each other. Moreover, the filtering is located in the bitstream before (in front of) the data including slice image data even when the coding of the slice data and the filtering data is performed in a reverse order.

Description

Coding of control data for adaptive loop filters

The present invention relates to coding and decoding of image data. In particular, the present invention relates to coding and decoding of the image data using a variable length code and bitstream structure.

BACKGROUND OF THE INVENTION

At present, the majority of standardized video coding algorithms are based on hybrid video coding. Hybrid video coding methods typically combine several different lossless and lossy compression schemes in order to achieve the desired compression gain. Hybrid video coding is also the basis for ITU-T standards (H.26x standards such as H.261 , H.263) as well as ISO/IEC standards (MPEG-X standards such as MPEG-1 , MPEG-2, and PEG-4). The most recent and advanced video coding standard is currently the standard denoted as H.264/MPEG-4 advanced video coding (AVC) which is a result of standardization efforts by joint video team (JVT), a joint team of ITU-T and ISO/IEC MPEG groups. This codec is being further developed by Joint Collaborative Team on Video Coding (JCT-VC) under a name High-Efficiency Video Coding (HEVC), aiming, in particular at improvements of efficiency regarding the high-resolution video coding.

A video signal input to an encoder is a sequence of images called frames, each frame being a two-dimensional matrix of pixels. All the above-mentioned standards based on hybrid video coding include subdividing each individual video frame into smaller blocks consisting of a plurality of pixels. The size of the blocks may vary, for instance, in accordance with the content of the image. The way of coding may be typically varied on a per block basis. The largest possible size for such a block, for instance in HEVC, is 64 x 64 pixels. It is then called the largest coding unit (LCU). In H.264/MPEG-4 AVC, a macroblock (usually denoting a block of 16 x 16 pixels) was the basic image element, for which the encoding is performed, with a possibility to further divide it in smaller subblocks to which some of the coding/decoding steps were applied. Typically, the encoding steps of a hybrid video coding include a spatial and/or a temporal prediction. Accordingly, each block to be encoded is first predicted using either the blocks in its spatial neighborhood or blocks from its temporal neighborhood, i.e. from previously encoded video frames. A block of differences between the block to be encoded and its prediction, also called block of prediction residuals, is then calculated. Another encoding step is a transformation of a block of residuals from the spatial (pixel) domain into a frequency domain. The transformation aims at reducing the correlation of the input block. Further encoding step is quantization of the transform coefficients. In this step the actual lossy (irreversible) compression takes place. Usually, the compressed transform coefficient values are further compacted (losslessly compressed) by means of an entropy coding. In addition, side information necessary for reconstruction of the encoded video signal is encoded and provided together with the encoded video signal. This is for example information about the spatial and/or temporal prediction, amount of quantization, etc.

Figure 1 is an example of a typical H.264/MPEG-4 AVC and/or HE C video encoder 100. A subtracter 105 first determines differences e between a current block to be encoded of an input video image (input signal s) and a corresponding prediction block s, which is used as a prediction of the current block to be encoded. The prediction signal may be obtained by a temporal or by a spatial prediction 180. The type of prediction can be varied on a per frame basis or on a per block basis. Blocks and/or frames predicted using temporal prediction are called "inter"-encoded and blocks and/or frames predicted using spatial prediction are called "intra"-encoded. Prediction signal using temporal prediction is derived from the previously encoded images, which are stored in a memory. The prediction signal using spatial prediction is derived from the values of boundary pixels in the neighboring blocks, which have been previously encoded, decoded, and stored in the memory. The difference e between the input signal and the prediction signal, denoted prediction error or residual, is transformed 1 10 resulting in coefficients, which are quantized 120. Entropy encoder 190 is then applied to the quantized coefficients in order to further reduce the amount of data to be stored and/or transmitted in a lossless way. This is mainly achieved by applying a code with code words of variable length wherein the length of a code word is chosen based on the probability of its occurrence.

Within the video encoder 100, a decoding unit is incorporated for obtaining a decoded (reconstructed) video signal s'. In compliance with the encoding steps, the decoding steps include inverse transformation 130. The so obtained prediction error signal e' differs from the original prediction error signal due to the quantization error, called also quantization noise. A reconstructed image signal s' is then obtained by adding the decoded prediction error signal e' to the prediction signal s. In order to maintain the compatibility between the encoder side and the decoder side, the prediction signal s is obtained based on the encoded and subsequently decoded video signal which is known at both sides the encoder and the decoder.

Due to the quantization, quantization noise is superposed to the reconstructed video signal. Due to the block-wise coding, the superposed noise often has blocking characteristics, which result, in particular for strong quantization, in visible block boundaries in the decoded image. Such blocking artifacts have a negative effect upon human visual perception. In order to reduce these artifacts, a deblocking filter 140 is applied to every reconstructed image block. The deblocking filter is applied to the reconstructed signal s'. For instance, the deblocking filter of H.264/MPEG- 4 AVC has the capability of local adaptation. In the case of a high degree of blocking noise, a strong (narrow-band) low pass filter is applied, whereas for a low degree of blocking noise, a weaker (broad-band) low pass filter is applied. The strength of the low pass filter is determined by the prediction signal s and by the quantized prediction error signal e'. Deblocking filter generally smoothes the block edges leading to an improved subjective quality of the decoded images. Moreover, since the filtered part of an image is used for the motion compensated prediction of further images, the filtering also reduces the prediction errors, and thus enables improvement of coding efficiency.

After a deblocking filter, a sample adaptive offset 150 and/or adaptive loop filter 160 may be applied to the image including the already deblocked signal s". Whereas the deblocking filter improves the subjective quality, sample adaptive offset (SAO) and ALF aim at improving the pixel-wise fidelity ("objective" quality). In particular, SAO adds an offset in accordance with the immediate neighborhood of a pixel. The adaptive loop filter (ALF) is used to compensate image distortion caused by the compression. Typically, the adaptive loop filter 160 is a Wiener filter with filter coefficients determined such that the mean squared error (MSE) between the reconstructed s" and source images s is minimized. The coefficients of ALF may be calculated and transmitted on a frame basis. ALF can be applied to the entire frame (image of the video sequence) or to local areas (blocks). Additional side information indicating which areas are to be filtered may be transmitted (block-based, frame-based or quadtree-based). Both, ALF and SAO may be adaptive. This means that their parameters are determined at the encoder, at which the original signal is still available. Figure 1 illustrates this by means of an estimator 155 for estimating SAO control parameters and an estimator 165 for estimating ALF control parameters. The SAO and/or ALF control parameters are then fed to the entropy encoder where they are encoded and inserted into the bitstream which also includes the encoded image data. In order to be decoded, inter-encoded blocks require also storing the previously encoded and subsequently decoded portions of image(s) in the reference frame buffer 170. An inter-encoded block is predicted 180 by employing motion compensated prediction. First, a best-matching block is found for the current block within the previously encoded and decoded video frames by a motion estimator. The best-matching block then becomes a prediction signal and the relative displacement (motion) between the current block and its best match is then signalized as motion data in the form of three-dimensional motion vectors within the side information provided together with the encoded video data. The three dimensions consist of two spatial dimensions and one temporal dimension. In order to optimize the prediction accuracy, motion vectors may be determined with a spatial sub-pixel resolution e.g. half pixel or quarter pixel resolution. A motion vector with spatial sub-pixel resolution may point to a spatial position within an already decoded frame where no real pixel value is available, i.e. a sub-pixel position. Hence, spatial interpolation of such pixel values is needed in order to perform motion compensated prediction. This may be achieved by an interpolation filter (in Figure 1 integrated within Prediction block 180).

For both, the intra- and the inter-encoding modes, the differences e between the current input signal and the prediction signal are transformed 1 10 and quantized 120, resulting in the quantized coefficients. Generally, an orthogonal transformation such as a two-dimensional discrete cosine transformation (DCT) or an integer version thereof is employed since it reduces the correlation of the natural video images efficiently. After the transformation, lower frequency components are usually more important for image quality then high frequency components so that more bits can be spent for coding the low frequency components than the high frequency components. In the entropy coder, the two-dimensional matrix of quantized coefficients is converted into a one-dimensional array. Typically, this conversion is performed by a so-called zig-zag scanning, which starts with the DC-coefficient in the upper left corner of the two- dimensional array and scans the two-dimensional array in a predetermined sequence ending with an AC coefficient in the lower right corner. As the energy is typically concentrated in the left upper part of the two-dimensional matrix of coefficients, corresponding to the lower frequencies, the zig-zag scanning results in an array where usually the last values are zero. This allows for efficient encoding using run-length codes as a part of/before the actual entropy coding.

The H.264/MPEG-4 H.264/MPEG-4 AVC as well as HEVC includes two functional layers, a Video Coding Layer (VCL) and a Network Abstraction Layer (NAL). The VCL provides the encoding functionality as briefly described above. The NAL encapsulates information elements into standardized units called NAL units according to their further application such as transmission over a channel or storing in storage. The information elements are, for instance, the encoded prediction error signal or other information necessary for the decoding of the video signal such as type of prediction, quantization parameter, motion vectors, etc. There are VCL NAL units containing the compressed video data and the related information, as well as non- VCL units encapsulating additional data such as parameter set relating to an entire video sequence, or a Supplemental Enhancement Information (SEI) providing additional information that can be used to improve the decoding performance. Typically, a VCL NAL unit includes encoded data of a slice, namely a slice header with parameters relating to coding of the entire slice and with slice data.

Figure 2 illustrates an example decoder 200 according to the H.264/MPEG-4 AVC or HEVC video coding standard. The encoded video signal (input signal to the decoder) first passes to entropy decoder 290, which decodes the quantized coefficients, the information elements necessary for decoding such as motion data, mode of prediction etc. The quantized coefficients are inversely scanned in order to obtain a two-dimensional matrix, which is then fed to inverse quantization and inverse transformation 230. After inverse quantization and inverse transformation 230, a decoded (quantized) prediction error signal e' is obtained, which corresponds to the differences obtained by subtracting the prediction signal from the signal input to the encoder in the case no quantization noise is introduced and no error occurred.

The prediction signal is obtained from either a temporal or a spatial prediction 280. The decoded information elements usually further include the information necessary for the prediction such as prediction type in the case of intra-prediction and motion data in the case of motion compensated prediction. The quantized prediction error signal in the spatial domain is then added with an adder 240 to the prediction signal obtained either from the motion compensated prediction or intra-frame prediction 280. The reconstructed image s' may be passed through a deblocking filter 250, sample adaptive offset processing 255, and an adaptive loop filter 260 and the resulting decoded signal is stored in the memory 270 to be applied for temporal or spatial prediction of the following blocks/images.

The entropy encoding 190 and entropy decoding 290 apply variable length encoding and decoding, respectively, to the image data and to the control data. As shown above, the coding of the prediction error generally includes a transformation and quantization of the transformation coefficients. In order to reduce quantization errors, in loop filtering approaches are applied. Typically, deblocking filtering and adaptive filter techniques such as sample adaptive offset and adaptive loop filtering are applied. At the encoder side, the sample adaptive offset and adaptive loop filter determine control data which is used to ensure that the same processing is applied at the encoder and at the decoder. The control data is then encoded and transmitted to the receiver within the bit stream. The receiver decodes the control data and performs the sample adaptive offset and adaptive loop filtering accordingly. In order to exploit the benefits of sample adaptive offset and adaptive loop filtering, the control data is to be estimated individually for each individual picture of a sequence. An optimal estimation of parameters (control data) requires the original signal as well as the process signal to which the filtering is to be applied. This is, for instance, the signal after deblocking filtering of the entire slice or picture. The control data may be transmitted together with other header information within the picture parameter set or in the slice header. The control data is advantageously further encoded by arithmetic coding and embedded into the bitstream, which requires the following coding steps (cf. HM3.0).

Encoding and decoding the picture or portion of the picture (for instance, slice) and buffering all associated syntax elements. The encoding and decoding is performed up to but not including the filter operation for which the parameters are estimated. For instance, the encoding and decoding is performed including deblocking filtering 140 but not including sample adaptive offset 150 and adaptive loop filtering 160.

The parameters of the adaptive filtering mechanisms are estimated. For instance, sample adaptive offset control parameters are estimated 155, 156 based on the original signal and on the deblocked signal. The sample adaptive offset is then applied to the picture or a portion of the picture using the estimated sample adaptive offset control parameters. Based on the original signal and on the signal processed by sample adaptive offset, the adaptive loop filtering control parameters may be determined. As a next step, the picture or a portion of the picture is applied adaptive loop filtering to, by using the estimated control parameters.

The sample adaptive offset control parameters and the adaptive loop filtering control parameters are encoded and inserted into the bit stream, for instance, into the header. All the buffered syntax elements are then encoded.

As can be seen in the above example, all the syntax elements of the picture or a portion of the picture are buffered. This leads to increased requirements on the amount of memory. Moreover, coding of the buffered syntax elements after the determination and coding of the sample adaptive offset and adaptive loop filter control parameters also results in undesired delay. The increased requirements on memory and the delay may lead to higher costs of the corresponding devices. SUMMARY OF THE INVENTION

The aim of the present invention is to reduce the memory requirements and/or delay and to thus enable a more efficient implementation of adaptive loop filtering techniques.

This is achieved by the features of the independent claims.

Advantageous embodiments are the subject matter of the dependent claims.

It is the particular approach of the present invention to provide a bitstream organization regarding the slice data and filtering parameters related to filtering of the slice data in which the slice data and the filtering data are encodeable and decodeable independently from each other. Moreover, a decoder-friendly ordering in which the filtering data precede the slice data is adopted.

In accordance with an aspect of the present invention, a method for encoding slices of image data into a bitstream is provided including the steps of: encoding a slice of image data with a variable length code; estimating parameters for in-loop filtering the slice of image data; encoding the estimated parameters with a variable length code, wherein the encoding of the slice of image data and the encoding of the estimated parameters are performed independently of each other; and inserting the encoded parameters into the bitstream before the encoded slice of image data.

Similarly, in accordance with another aspect of the present invention, a method for decoding slices of image data from a bitstream is provided including the steps of: extracting from the bitstream encoded parameters and then encoded slice of a slice of image data which follow the encoded parameters in the bitstream; decode the encoded parameters for in-loop filtering of the slice of the image data using a variable length code, wherein the decoding of the slice of image data and the decoding of the estimated parameters are performed independently of each other; and decode the slice of image data sing a variable length code.

In particular, slice of image data includes an encoded pixel data of a video picture or a portion of a video picture.

Preferably, the variable length code applied for encoding of the slice of image data is arithmetic code. Still preferably, the variable length code applied for encoding of the estimated parameters is a code other than arithmetic code. Advantageously, the encoding of the filtering data is performed after the encoding the slice of image data,

However, it is noted that the present invention is not limited thereto and that both the slice data and the filtering data may be encoded with arithmetic coding or both may be encoded with a variable length coding other than arithmetic coding such as exp-Golomb, Golomb, Elias or other integer codes.

The in-loop filtering is preferably an adaptive loop filtering and/or sample adaptive offset.

However, adaptive deblocking filtering may also be applied in accordance with the present invention or any other in-loop filtering.

Advantageously, the bitstream comprises a slice header followed by the encoded slice data and the estimated parameters are included in a separate parameter set.

The estimated parameters may include at least one of a flag for signaling whether a filtering is to be applied to the slice of data, a filter indicator for indicating which the filter is to be used for filtering of the slice data, offset, and filter coefficients.

In accordance with a further aspect of the present invention, a computer program product is provided comprising a computer-readable medium having a computer-readable program code embodied thereon, the computer program code being adapted to carry out the steps of any of the above described methods.

In accordance with another aspect of the present invention, an apparatus is provided for encoding slices of image data into a bitstream including: an image data encoder for encoding a slice of image data with a variable length code; an estimator for estimating parameters for in- loop filtering the slice of image data; a control data encoder for, after encoding the slice of image data, encoding the estimated parameters with a variable length code, wherein the encoding of the slice of image data and the encoding of the estimated parameters are performed independently of each other; and a bitsrtream generator for inserting the encoded parameters into the bitstream before the encoded slice of image data.

In accordance with another aspect of the present invention, an apparatus is provided for decoding slices of image data from a bitstream including: a bitstream parser for extracting from the bitstream encoded parameters and then encoded slice of a slice of image data which follow the encoded parameters in the bitstream; a control data decoder for decoding the encoded parameters for in-loop filtering of the slice of the image data using a variable length code wherein the decoding of the slice of image data and the decoding of the estimated parameters are performed independently of each other; an image data decoder for decode the slice of image data sing a variable length code.

The above and other objects and features of the present invention will become more apparent from the following description and preferred embodiment given in conjunction with the accompanying drawings in which:

Figure 1 is a block diagram schematically illustrating an HEVC encoder;

Figure 2 is a block diagram schematically illustrating an HEVC decoder;

Figure 3 is a schematic drawing illustrating bitstream organization of post-filtering data and the slice data in H.264/MPEG-4 AVC;

Figure 4 is a schematic drawing illustrating bitstream organization of filtering data and slice data in HM3.0;

Figure 5 is a schematic drawing illustrating bitstream organization of filtering data and slice data in a proposal within the HEVC standardization;

Figure 6 is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data;

Figure 7 is a schematic drawing illustrating an example of arithmetic encoding of the slice data;

Figure 8 is a schematic drawing illustrating an example of bitstream portion including slice data and in the slice header the filtering data;

Figure 9 is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data;

Figure 10 is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data;

Figure 1 1 is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data; is a schematic drawing illustrating an example of bitstream organization of filtering data and slice data including filtering data indexes; is a schematic drawing illustrating an overall configuration of a content providing system for implementing content distribution services; is a schematic drawing illustrating an overall configuration of a digital broadcasting system; is a block diagram illustrating an example of a configuration of a television; is a block diagram illustrating an example of a configuration of an information reproducing/recording unit that reads and writes information from or on a recording medium that is an optical disk; is a schematic drawing showing an example of a configuration of a recording medium that is an optical disk; is a schematic drawing illustrating an example of a cellular phone; is a block diagram showing an example of a configuration of the cellular phone; is a schematic drawing showing a structure of multiplexed data; is a drawing schematically illustrating how each of the streams is multiplexed in multiplexed data; is a schematic drawing illustrating how a video stream is stored in a stream of PES packets in more detail; is a schematic drawing showing a structure of TS packets and source packets in the multiplexed data; is a schematic drawing showing a data structure of a PMT; is a schematic drawing showing an internal structure of multiplexed data information; is a schematic drawing showing an internal structure of stream attribute information; is a schematic drawing showing steps for identifying video data; is a schematic block diagram illustrating an example of a configuration of an integrated circuit for implementing the video coding method and the video decoding method according to each of embodiments; is a schematic drawing showing a configuration for switching between driving frequencies; Figure 38 is a schematic drawing showing steps for identifying video data and switching between driving frequencies;

Figure 39 is a schematic drawing showing an example of a look-up table in which the standards of video data are associated with the driving frequencies;

Figure 40A is a schematic drawing showing an example of a configuration for sharing a module of a signal processing unit; and

Figure 40B is a schematic drawing showing another example of a configuration for sharing a module of a signal processing unit.

DETAILED DESCRIPTION

The problem underlying the present invention is based on the observation that the selection of the variable length coding applied to the image data and control information as well as ordering of the encoded data in the bitstream has an impact on the decoding efficiency.

In order to avoid delays at the decoder, the present invention provides a structure of the bitstream in which the filtering parameters are included in the bitstream before the image data, to which the filter specified by the parameters is to be applied. Moreover, the encoding of the image data is performed before the encoding of the filtering parameters. This is advantageous since the filtering parameters are typically estimated based on the image data. The encoding of the image data is performed independently of the filtering parameter data which enables exchanging the order of the encoded data in the bitstream with respect to the order of encoding.

Moreover, in accordance with an embodiment of the present invention, byte alignment and individual start codes are introduced in order to enable faster and/or parallel parsing of the control data (filtering parameters) and the remaining slice/picture data (image data). This approach leads to initialization of the arithmetic coder before decoding of the control data such as sample adaptive offset and adaptive loop filtering. In particular, the initialization includes probability estimators and interval division. Moreover, the arithmetic coder is terminated after the coding of the control parameters. It is advantageous when the control parameters in slice header of PPS are restricted to the possibility of only using variable length coding and not arithmetic coding. Figure 3 illustrates bit stream organization in the H.264/MPEG-4 AVC standard. At the beginning of the encoded video sequence in the bit stream, picture parameter set (PPS) including parameters common for the entire sequence is transmitted. The PPS packet has a length which is an integer multiple of bytes (byte = 8 bits). This control data includes post filter data. Post filter is to be applied to the coded picture at the decoder after the picture data has been decoded. It is not applied at the encoder and during the encoding and/or decoding (in the loop). The PPS data is encoded by using an entropy encoder. However, arithmetic coding is not used for this purpose. Rather, an entropy code denoted in the figure as "variable length code" is applied. When the resulting data are not an integer multiple of bytes, alignments bits (BA) are inserted in such a manner that the PPS packet becomes an integer multiple of bytes.

The PPS packet is followed by the image data as described above, the pictures of the video sequence are segmented into slices and each slice is embedded within the bit stream preceded by a slice header. The slice header is also encoded by using the variable length code but not the arithmetic coding. The slice data may be coded by using arithmetic coding or alternatively by using variable length coding. Each packet containing the slice header and the slice data has to have a total length of integer multiple of bytes. In order to achieve this, after the slice header and the slice data are coded, alignment bits may be inserted. In this way, the slices of the video pictures are encoded each slice into a separate packet (NAL unit). In the case that the slice data is encoded by using arithmetic coding, the probability estimator and the intervals of the arithmetic coder are initialized after the slice header. The arithmetic coder is terminated after the slice data.

In the H.264/MPEG-4 AVC, the adaptive filter data (control data of adaptive loop filer) are transmitted within packets of SEI. These packets are also encoded using the variable length coding, but arithmetic coding is not allowed. SEI packets also have the length which is an integer multiple of bytes. In order to achieve this, alignment bits may be inserted. It is noted that the adaptive loop filter, the parameters of which are transmitted within the SEI message, is in the H.264/MPEG-4 AVC standard applied as post filter and not as a loop filter.

Figure 4 illustrates a bit stream organization in accordance with HM3.0. In particular, the bit stream organization includes the adaptive filtering information within the slice header. In particular, the sample adaptive offset and adaptive loop filtering control information is embedded immediately after the common information typically inserted into the slice header. Whereas the common information portion is encoded with variable length coding but not with arithmetic coding, the adaptive filtering control information may also be generated by arithmetic coding and is in general encoded together with the slice data. The control information is not necessarily sent in each slice. It is noted that the initialization of probability estimator and of the probability intervals used for arithmetic coding are performed within each slice after the common information. The adaptive loop filter information includes the filter coefficients for the adaptive loop filter and information to switch on/off adaptive loop filter for certain regions of a slice, namely coding units (CU).

A contribution to the HEVC standard with number JCTVC-E045 (submitted to the 5^th JCTVC meeting of the ISO and the ITU-T in Geneva and freely available at http://phenix.int- evry.fr/jct/doc_end_user/current_document.php?id=1957) suggests a bit stream organization, which is shown in Figure 5. The common information is transmitted within PPS packet together with the coefficients of the adaptive loop filter. The slice packets include a header which contains the adaptive loop filter coding unit on/off indicators. Accordingly, the encoding of the slice data is still performed together with the adaptive loop filter data such as adaptive loop filter CU on/off data. The contribution does not deal with the implementation of arithmetic coding for the suggested schemes such as re-starting of probability estimator and termination of arithmetic coding.

As can be seen from the bitstream organisation approaches described with reference to figures 3 to 5, the encoding and decoding of the adaptive loop filter data still lacks efficiency due to ordering of the filtering data after the image data to be filtered (inefficient in case of in-loop filtering) and/or because of the common arithmetic coding applied.

The present invention avoids the problems of the prior art by encoding the filter and image data in another order than the order of their insertion into the bitstream and by applying the variable length coding to these in-loop filtering data separately and independently of each other. It is noted that the in-loop filtering data may include adaptive loop filter data and/or the sample adaptive offset data.

Figure 6 illustrates an exemplary embodiment of the present invention. In particular, Figure 6 schematically shows a bitstream organization which enables a more efficient employment of the entropy coding. In accordance with this embodiment, a packet including signalling information common for the following plurality of data information packets such as PPS packets includes signalling data not related to adaptive loop filtering or sample adaptive offset. This data may correspond to the data transmitted within the PPS packet in the present state of the art. This data is preferably encoded with variable length code but not with an arithmetic code. This portion of the signalling packet is followed by the data related to adaptive loop filtering and sample adaptive offset (or in general, other filtering related data). This kind of data is preferably encodable with arithmetic coding as well. This assumes that the arithmetic coding is restarted at the beginning of this data as indicated in Figure 6 with an arrow. Alignment bits may be included where necessary in order to achieve the length of the signalling packet being an integer multiple of bytes. This signalling packet is then followed by packets containing slice data and related signalling information. The signalling information is embedded within the slice header followed by the slice data corresponding to the encoded picture information. Moreover, alignment bits may be inserted if necessary in order to arrive at the length of an integer multiple of bytes.

The slice data packet includes in the first slice header portion data other than adaptive loop filtering or sample adaptive offset data which are encoded by a variable length code not generated by arithmetic coding. This portion of header is followed by another portion of the header, which includes the adaptive loop filtering and/or sample adaptive offset data which may be generated by arithmetic coding. Accordingly, the arithmetic code for coding this second portion of the slice header is restarted at the beginning of the second portion. The initialization of probability estimator and of the intervals of the arithmetic coder is performed at the end of the slice header and used for possible arithmetic coding of the slice data portion following the header. The arithmetic coder is terminated before the alignment bits are added.

As can be seen from Figure 6, the adaptive loop filtering data is transmitted before the slice data within the bit stream. This means that the decoder can decode adaptive loop filter data first, for instance, filter coefficients and/or on/off flags and decode the slice (picture) data on a block by block basis afterwards. The adaptive loop filtering may then be applied to each decoded block immediately without waiting until all blocks of the slice or picture are decoded. This enables a more efficient usage of the memory and a reduction in delay. Similarly, the sample adaptive offset data may also be transmitted before the slice data within the bit stream. Accordingly, the decoder does not need to wait and may immediately decode sample adaptive offset parameters such as the offsets and/or the on/off flags, then decode the slice or picture in a block wise manner and apply sample adaptive offset to each decoded block immediately without waiting until all blocks of the slice or picture are decoded.

This leads to a completely independent coding of the slice data and the adaptive loop filter data and possibly also of the sample adaptive filter data. Also the portions of adaptive loop filter data may be encoded independently of each other, which will be shown later. The encoder can thus encode and internally decode (reconstruct) all syntax elements of a slice and generate a first part of the bit stream. Then the encoder may determine the adaptive loop filter parameters in an optimal way since the decoded slice signal as well as the original signal are available. This may be performed, for instance, by applying a Wiener filtering approach. The determined adaptive loop filter parameters are encoded in a second part of the bit stream in order to provide the decoder with the adaptive loop filter data before the slice data, the second part and the first part of the bit stream are ordered in such a way that the second part is transmitted before the first part.

Similarly, the transmission of sample adaptive offset related data may be performed. As shown in Figure 6, the coding of the slice data is performed completely independently from the coding of the sample adaptive offset data and also independently from the portions of sample adaptive data itself, as will be shown below. Correspondingly to the adaptive loop filtering, the encoder can also encode and internally decode (reconstruct) all syntax elements of a slice and generate a first part of a bit stream. Then the encoder can determine the sample adaptive offset parameters as the decoded slice as well as the original signal are both available. The so- determined sample adaptive offset parameters are then encoded in a second part of a bit stream. In order to provide a decoder with the sample adaptive offset data before the slice data, the second part and the first part of the bit stream (order according to the encoding order) are reordered in such a way that the second part is transmitted before the first part.

It is noted that in general, the variable length coding is applied to both image data and control data. This does not exclude the possibility that some particular syntax elements of the control parameters may also be encoded with a fixed-length code. The variable length coding here denotes any coding by means of codewords the length of which may differ. For instance, variable length coding may be arithmetic coding or another coding such as Hamming coding or integer codes such as Elias, Golomb or other codes. It may be advantageous to apply arithmetic coding to the image data. Arithmetic coding is particularly efficient for larger coding blocks. The signalling data may efficiently be encoded using variable length codes other than arithmetic codes. However, this invention is not limited to any of the particular codes and the control data may also be encoded with an arithmetic code.

Figure 7 illustrates restarting of the arithmetic coding when starting the encoding of the slice of the image data. This is also one of the means for achieving independent coding of slice data and the filtering (ALF and/or SAO) data for the case in which the arithmetic coding is applied to both image data and the signalling data. As can be seen in Figure 7, the slice header in this example includes filtering data for in-loop filtering such as ALF or SAO data (or both). The slice data does not include the filtering data but rather the coded pixel data information. The filtering information and possibly also other parts of the slice header are encoded using an arithmetic code. After the slice header, the arithmetic code is restarted. This means that the probability estimator and the intervals of the arithmetic coder/decoder are initialized. This is exemplified in Figure 7 by showing the initial intervals given by the probability pi of 1 (a first binary symbol) and 1 (a second binary symbol). The first data symbol is coded accordingly. Arithmetic coding, as known from the state of the art, encodes a sequence of symbols by means of a single codeword which corresponds to a position within the probability range (between 0 and 1 ). This is performed by dividing the probability intervals according to the symbols being encoded. The second symbol to be coded in the example of Figure 7 is "1 ". Accordingly, the codeword will be located within the probability interval of 0 to p, . This interval is further subdivided to two intervals, 0 to p₂*Pi and p₂*pi to pi . The probabilities p, with integer i are estimated probabilities of the binary symbols to be encoded in the step i. The third symbol to be encoded is 0. Accordingly, the higher interval p₂*pi to pi is taken and further subdivided to two intervals by the estimated probability p₃ as p₂ · p_l + p₃ · (/?, - p₂ ^■ ?, ) . Initialization of intervals of the arithmetic coder may mean to set the lowest interval border to the lowest possible value, which is generally „0" (equal to a probability of zero) and the highest interval border to the highest possible value, which is generally„1 " (equal to a probability of one). These values may be slightly different in certain implementations, e.g. due to restrictions in the representations of numbers. More information to the principles of arithmetic coding may be found, for instance in the Section 1 1 .4.4 of the book "Multimedia Communication Technology" by J.-R. Ohm, Springer Verlag, 2004. The arithmetic coding terminates at the end of the slice as also illustrated in Figure 7.

The present invention thus enables independent coding of slice data from ALF and/or SAO data. The same is applicable also for the case in which the slice image data are not coded by arithmetic coding as shown in Figure 8. The slice header data may but is not necessarily encoded with the arithmetic data. In this embodiment, if the slice data consists of the symbols a_l , ... ,a_k ,... ,a_K to be coded (k=1..K), the codeword of each symbol a_k are selected independently from ALF/SAO data and/or ALF/SAO bit stream.

Figure 9 shows another embodiment of the present invention in which the loop filtering data are associated to the slice data and in which both the filter data and the image data are generated by arithmetic coding. In this example, a portion of the filtering data is transmitted in the PPS and another portion of the filtering data within the slice header. The bitstream organization thus shows a first packet including PPS data other than ALF/SAO data followed by the ALF/SAO data and byte alignment bits. In general, PPS is a separate packet within the bitstream comprising signalling data with parameters common for the sequence of images. As shown in Figure 9, preferably, the arithmetic code is restarted after coding the non-filtering data and after the filtering data. The packets following the PPS include a slice header portion with data other than the filtering (ALF/SAO) data and a potion with ALF/SAO data followed by the slice data which do not include ALF/SAO data and possibly with the byte alignment (BA). In this example, the portion of the slice header not including filtering data is not encoded by arithmetic coding. Accordingly, the arithmetic coder/decoder is restarted after this portion when the portion including the filtering data starts. The arithmetic code is further initialized at the start of the slice data. This enables independent coding of the slice data and the filtering data.

Figure 10 illustrates another embodiment of the present invention. It differs from the embodiment described with reference to Figure 9 in that the ordering of the filtering data within the slice header is not necessarily at the end of the slice header. The present invention is applicable with any ordering of the filtering data within the bitstream. Accordingly, the filtering (ALF/SAO) data may be transmitted within a separate packet and/or within a slice header of a slice data packet. In the slice header, the position of the filtering data may be any of the available positions. Figure 10 illustrates an example, in which the filtering data is preceded and followed by other control data ("(other than ALF/SAO data)"). Here, the filtering data is exemplary encoded with an arithmetic coding whereas other portions of the heads are encoded with another type of the variable length encoding in order to show that restart of arithmetic encoder/decoder is performed at the start of the filtering data portion and the slice data portion so as to enable individual treatment of filtering data and the slice data. In the figures, the smaller full arrow indicates initialization of the probability model of the arithmetic code and the bigger line-drawn arrow illustrates termination of the arithmetic code (the arithmetic code codeword).

Figure 11 illustrates another embodiment of the present invention. In particular, it shows that the present invention is applicable irrespectively of the variable length code type applied to the control and slice data portions. This is indicated in the figure by "variable length code (VLC) which may be generated by arithmetic coding". As emphasized above, the present invention enables an effective encoding by encoding the in-loop filtering data independently from the slice data to be filtered and by ordering the encoded slice data and filtering data decoder-friendly. This does not depend on the applied entropy coding. Accordingly, Figure 1 1 shows that the control data and filtering data may be transmitted in a separate packet (PPS) and/or within the slice header. It further shows that each portion such as filtering data, control data other than filtering data and slice data is encoded by a variable length code which may be but is not necessarily an arithmetic code. As discussed above, in order to enable independent decoding of the filtering data and the slice data, the arithmetic code is advantageously restarted at the beginning of each of the filtering data and the slice data and correspondingly also terminated.

Figure 12 shows another example, in which the filtering data is encoded within an arithmetic code codeword together with other control data. The filtering data may also be coded with all the remaining control data in the separate packet and/or in the slice header. This is illustrated by the indication that a portion of the PPS and/or i-th (i being 1 to N) slice header is coded by a variable length code other than arithmetic code and another portion thereof is encoded together with the filtering data (ALF/SAO) in one codeword of the arithmetic code. Accordingly, the restart of the arithmetic code corresponds to the start of the non-filtering data portion to be coded by arithmetic coding. The arithmetic code terminates and restarts again at the beginning of the slice data. It is noted that an efficient coding of most header information would be to use arithmetic coding. Therefore, in this example only a small (first) part of PPS/slice header information is coded using non-arithmetic coding (for instance, only the start code). It is notes that also here, the slice data and the filtering data is not necessarily coded by the arithmetic coding and a different coding may be applied.

Figure 13 illustrates an example in which the filtering data for different filter types are coded separately. This means that a separate arithmetic code codewords are generated for different filter data. For instance, an individual arithmetic codeword is generated for the ALF data and for the SAO data. This approach has the advantage that no syntax elements need to be stored in the case of multiple filters (SAO, ALF). It is noted that the present invention is not limited to SAO and ALF and that other in-loop filters may also be handled similarly. For instance, if deblocking filter is an adaptive filter or if another filter is applied to the loop data, the present invention is also applicable therefor. Figure 13 shows that the filtering data related to two different filter types (filtering stages within the loop) may be encoded individually in case they are embedded within a separate packet (PPS) and/or in case when they are embedded within a slice header or the slice headers of the packets carrying the slice data. Correspondingly, the arithmetic coding is restarted (initialized) at the start of the particular filtering data (ALF, SAO) and terminated at the end of the coded individual filtering data. As also shown in Figure 13 ("may be generated"), the portions of the filtering data may be also encoded with other than arithmetic code. For instance, SAO data may be encoded with an arithmetic code and ALF data with another than arithmetic variable length code or vice versa. They may also be encoded both with a non- arithmetic variable length code as long as they are encoded independently from the slice data and from each other. Combinations of the above described embodiments are also possible. Figure 14 illustrates one of such combinations. The embodiment of Figure 14 differs from the embodiment of Figure 13 in that the portions of the control data other than filtering data and the filtering data may be encoded together in a common codeword of arithmetic code as already exemplified in Figure 12. This embodiment combines the advantages of utilizing arithmetic code where possible as it is an efficient coding approach with the advantages of not having to store the syntax elements when a plurality of different filter stages are applied.

Figure 15 is another example of a bitstream organization enabling an individual encoding and decoding of the slice data and the filtering data and the filtering data related to filtering at different stages. Accordingly, the filtering data are not generated by the arithmetic coding whereas the arithmetic coding may be applied to control data other than filtering data. The slice data may also be encoded with the arithmetic code. The corresponding arithmetic code initialization and termination are illustrated by a full and a line-drawn arrows respectively.

It is noted that the figures are illustrative and show two cases - including of the control data into a separate parameter set (separate "packet") and including of the control data into the slice header. However, the present invention does not have to be applied to both. It can be applied to either of them. For instance, the filtering data may be included only into a separated parameter set (such as PPS packet in H.264/MPEG-4 AVC or in general a separate packet within a bitstream) or only into the slice header. Of course, a combination of both is also possible.

Figure 16 shows another exemplary embodiment of the present embodiment. Accordingly, in order to make easier the search for the filtering data within the bitstream, the filtering data of particular filter stages are byte-aligned separately. This enables parallel parting of the filtering data used for filtering at different loop decoding stages. The separate byte alignment is illustrated by the "BA" portions which are inserted, if necessary for the purpose of byte alignment, after each of the control data other than filtering data, after each particular filtering data and finally after the slice data.

Alternatively or in addition, start codes are inserted at the beginning of each separately decodable (and thus parallelizable) portion of control and slice data. The use of start codes increases the error resilience since in the case of an error it could be searched for the next code. In general, variable length coding is an efficient means for losslessly compressing the bitstream. However, since the codewords may have a different length, as soon as an error such as a bit inversion occurs, the codeword as well as its length may be wrongly decoded, which may result in errors in detection also in the following codewords. In order to avoid such desynchronization of the decoding, in this embodiment. Start codes are inserted at the beginning of each separately decodable portion. Start codes enable identification of the bitstream portion. They may be, for instance, unique sequences which do not occur within the variable length code encoded stream. The effect of the start codes is that even if an error occurs in one portion, the other portions may still be decoded. The start coder are denoted as "SC" in Figure 16. The start codes may be inserted, for instance at the beginning of the filtering data and then at the beginning of the slice data. This enables independency of the decodeability of the slice data and the filtering data with respect to errors. However, the start codes may also be inserted at the beginning of each portion carrying the data related to a particular filtering type/stage. This makes the filtering data of one type independent of an error which may occur in the bitstream portion corresponding to filtering data of another type.

Figure 17 shows an example, in which the filtering data are provided within a separate parameter set (packet) within the bitstream. In this example, the filtering data ("ALF/SAO-data") is generated by an arithmetic coding but in general, it may also be encoded by another type of variable length coding. The separate parameter set is also separately byte-aligned. In case of applying the arithmetic coding, the coding (and decoding) is initialized at the start of the parameter set (equal to the packet in this case) and terminates at its end before the byte- alignment. As can be seen in Figure 17, the slice header does not include the filtering data. The PPS packet at the beginning of the picture sequence also does not carry filtering data in this example. Regarding the byte-alignment, it is noted that it is not always necessary. If the encoded packet is an integer multiple of the byte, no byte-alignment (BA) bits are necessary.

Figure 18 illustrates another example of the present invention, differing from the previous example in that separate packets (NAL units) are used for the filtering data relating to different filtering stages (types of filters). In this example the different filtering stages are SAO and ALF stages. However, it is noted that the present invention is not limited thereto and, in general, other filtering types may also be applied adaptively so that the filtering data may be encoded as provided in the present invention. There should be the freedom to either transmit the seperate NAL unit for ALF/SAO-data before or after associated slice data. Typically, before the slice data is beneficial for a decoder and after the slice data is beneficial for the encoder. As can be seen in the example of Figure 18, the separate NAL-units for the separate filter data are also individually byte-aligned. Figure 19 shows organizing the filtering data of different stages into common portions within a separate packet (NAL unit). This filtering data includes data which is usable for filtering of multiple slices of image data. In addition, slice header of packets carrying slice data includes filtering data which are specific for the given slice. The filtering data may be encoded by arithmetic coding which is particularly beneficial for the separate NAL unit (packet) since the arithmetic coding efficiency increases with the length of the data to be coded. The portion corresponding to filtering data embedded in the slice header may be generated by an arithmetic code. However, it may be also generated by another type of variable length coding.

Finally, Figure 20 illustrates an embodiment which differs from the embodiment of Figure 19 in that separate packets (NAL units) are provided for filtering data of separate filtering stages / filter types as already shown in Figure 18.

Further variants of filtering data organization in the bitstream may be beneficial for more efficient encoding and/or decoding.

In accordance with another embodiment of the present invention, coding of the filtering (ALF/SAO) data in the slice header uses arithmetic coding and assigns individual codewords to each of the ALF data and SAO data. Even a further subdivision into more codewords may be useful, for instance, one for each LCU or for a sequence of LCUs. This enables parallel parting of filtering data for smaller portions of the image and thus, parallel processing of such portions, for instance, LCUs. Parallel decoding may be beneficial especially for high mage resolutions.

In accordance with a further embodiment of the present invention, each NAL unit containing filtering data (ALF and/or SAO data) should contain an index that is referred to in the respective slice headers. This is illustrated in Figure 21.

In particular, alf_data_id and/or sao_data_id is an index present in the NAL unit for the ALF/SAO data and in the slice headers of slices using ALF or SAO. The index in the slice header should correspond to the index of the NAL unit containing the ALF/SAO data corresponding to the slice (to be used for the filtering of the slice). Two NAL units with different ALF/SAO information (coefficients or CU flags) should have a different index. A NAL unit for ALF/SAO data should be transmitted:

- Before transmission of the first slice using that particular NAL unit, and

- Directly after transmission of the first slice using that particular NAL unit The index can be coded using variable length codes, e.g. exp-Golomb codes. Codes which can be calculated and which are able to code arbitrary indexes, e.g. not limited to a specific range (e.g. 0-255) are benficial to have unique NAL unit indexes.

As can be seen in Figure 21 , each slice can use ALF-data only from NAL-Units transmitted before or right afterwards (They cannot use ALF-data from the NAL-unit with the ID=m). This enables limiting the decoding delay.

Hereinafter, the applications to the video coding method and the video decoding method described in each of embodiments and systems using thereof will be described.

Figure 22 illustrates an overall configuration of a content providing system ex100 for implementing content distribution services. The area for providing communication services is divided into cells of desired size, and base stations ex106, ex107, ex108, ex109, and ex1 10 which are fixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as a computer ex111 , a personal digital assistant (PDA) ex112, a camera ex1 13, a cellular phone ex114 and a game machine ex115, via the Internet ex101 , an Internet service provider ex102, a telephone network ex104, as well as the base stations ex106 to ex1 10, respectively.

However, the configuration of the content providing system ex100 is not limited to the configuration shown in Figure 22, and a combination in which any of the elements are connected is acceptable. In addition, each device may be directly connected to the telephone network ex104, rather than via the base stations ex106 to ex110 which are the fixed wireless stations. Furthermore, the devices may be interconnected to each other via a short distance wireless communication and others.

The camera ex1 13, such as a digital video camera, is capable of capturing video. A camera ex1 16, such as a digital video camera, is capable of capturing both still images and video. Furthermore, the cellular phone ex1 14 may be the one that meets any of the standards such as Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wideband-Code Division Multiple Access (W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access (HSPA). Alternatively, the cellular phone ex114 may be a Personal Handyphone System (PHS).

In the content providing system ex100, a streaming server ex103 is connected to the camera ex1 13 and others via the telephone network ex104 and the base station ex109, which enables distribution of images of a live show and others. In such a distribution, a content (for example, video of a music live show) captured by the user using the camera ex113 is coded as described above in each of embodiments, and the coded content is transmitted to the streaming server ex103. On the other hand, the streaming server ex103 carries out stream distribution of the transmitted content data to the clients upon their requests. The clients include the computer ex11 1 , the PDA ex112, the camera ex113, the cellular phone ex1 14, and the game machine ex115 that are capable of decoding the above-mentioned coded data. Each of the devices that have received the distributed data decodes and reproduces the coded data.

The captured data may be coded by the camera ex1 13 or the streaming server ex103 that transmits the data, or the coding processes may be shared between the camera ex1 13 and the streaming server ex103. Similarly, the distributed data may be decoded by the clients or the streaming server ex103, or the decoding processes may be shared between the clients and the streaming server ex103. Furthermore, the data of the still images and video captured by not only the camera ex113 but also the camera ex116 may be transmitted to the streaming server ex103 through the computer ex11 1. The coding processes may be performed by the camera ex1 16, the computer ex1 1 1 , or the streaming server ex103, or shared among them.

Furthermore, the coding and decoding processes may be performed by an LSI ex500 generally included in each of the computer ex1 1 1 and the devices. The LSI ex500 may be configured of a single chip or a plurality of chips. Software for coding and decoding video may be integrated into some type of a recording medium (such as a CD-ROM, a flexible disk, and a hard disk) that is readable by the computer ex1 1 1 and others, and the coding and decoding processes may be performed using the software. Furthermore, when the cellular phone ex114 is equipped with a camera, the image data obtained by the camera may be transmitted. The video data is data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers and computers, and may decentralize data and process the decentralized data, record, or distribute data.

As described above, the clients may receive and reproduce the coded data in the content providing system ex100. In other words, the clients can receive and decode information transmitted by the user, and reproduce the decoded data in real time in the content providing system ex100, so that the user who does not have any particular right and equipment can implement personal broadcasting. Aside from the example of the content providing system ex100, at least one of the video coding apparatus and the video decoding apparatus described in each of embodiments may be implemented in a digital broadcasting system ex200 illustrated in Figure 23. More specifically, a broadcast station ex201 communicates or transmits, via radio waves to a broadcast satellite ex202, multiplexed data obtained by multiplexing audio data and others onto video data. The video data is data coded by the video coding method described in each of embodiments. Upon receipt of the multiplexed data, the broadcast satellite ex202 transmits radio waves for broadcasting. Then, a home-use antenna ex204 with a satellite broadcast reception function receives the radio waves.

Next, a device such as a television (receiver) ex300 and a set top box (STB) ex217 decodes the received multiplexed data, and reproduces the decoded data.

Furthermore, a reader/recorder ex218 (i) reads and decodes the multiplexed data recorded on a recording media ex215, such as a DVD and a BD, or (i) codes video signals in the recording medium ex215, and in some cases, writes data obtained by multiplexing an audio signal on the coded data. The reader/recorder ex218 can include the video decoding apparatus or the video coding apparatus as shown in each of embodiments. In this case, the reproduced video signals are displayed on the monitor ex219, and can be reproduced by another device or system using the recording medium ex215 on which the multiplexed data is recorded. It is also possible to implement the video decoding apparatus in the set top box ex217 connected to the cable ex203 for a cable television or to the antenna ex204 for satellite and/or terrestrial broadcasting, so as to display the video signals on the monitor ex219 of the television ex300. The video decoding apparatus may be implemented not in the set top box but in the television ex300.

Figure 24 illustrates the television (receiver) ex300 that uses the video coding method and the video decoding method described in each of embodiments. The television ex300 includes: a tuner ex301 that obtains or provides multiplexed data obtained by multiplexing audio data onto video data, through the antenna ex204 or the cable ex203, etc. that receives a broadcast; a modulation/demodulation unit ex302 that demodulates the received multiplexed data or modulates data into multiplexed data to be supplied outside; and a multiplexing/demultiplexing unit ex303 that demultiplexes the modulated multiplexed data into video data and audio data, or multiplexes video data and audio data coded by a signal processing unit ex306 into data.

The television ex300 further includes: a signal processing unit ex306 including an audio signal processing unit ex304 and a video signal processing unit ex305 that decode audio data and video data and code audio data and video data, respectively; and an output unit ex309 including a speaker ex307 that provides the decoded audio signal, and a display unit ex308 that displays the decoded video signal, such as a display. Furthermore, the television ex300 includes an interface unit ex317 including an operation input unit ex312 that receives an input of a user operation. Furthermore, the television ex300 includes a control unit ex310 that controls overall each constituent element of the television ex300, and a power supply circuit unit ex311 that supplies power to each of the elements. Other than the operation input unit ex312, the interface unit ex317 may include: a bridge ex313 that is connected to an external device, such as the reader/recorder ex218; a slot unit ex314 for enabling attachment of the recording medium ex216, such as an SD card; a driver ex315 to be connected to an external recording medium, such as a hard disk; and a modem ex316 to be connected to a telephone network. Here, the recording medium ex216 can electrically record information using a non-volatile/volatile semiconductor memory element for storage. The constituent elements of the television ex300 are connected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodes multiplexed data obtained from outside through the antenna ex204 and others and reproduces the decoded data will be described. In the television ex300, upon a user operation through a remote controller ex220 and others, the multiplexing/demultiplexing unit ex303 demultiplexes the multiplexed data demodulated by the modulation/demodulation unit ex302, under control of the control unit ex310 including a CPU. Furthermore, the audio signal processing unit ex304 decodes the demultiplexed audio data, and the video signal processing unit ex305 decodes the demultiplexed video data, using the decoding method described in each of embodiments, in the television ex300. The output unit ex309 provides the decoded video signal and audio signal outside, respectively. When the output unit ex309 provides the video signal and the audio signal, the signals may be temporarily stored in buffers ex318 and ex319, and others so that the signals are reproduced in synchronization with each other. Furthermore, the television ex300 may read multiplexed data not through a broadcast and others but from the recording media ex215 and ex216, such as a magnetic disk, an optical disk, and a SD card. Next, a configuration in which the television ex300 codes an audio signal and a video signal, and transmits the data outside or writes the data on a recording medium will be described. In the television ex300, upon a user operation through the remote controller ex220 and others, the audio signal processing unit ex304 codes an audio signal, and the video signal processing unit ex305 codes a video signal, under control of the control unit ex310 using the coding method described in each of embodiments. The multiplexing/demultiplexing unit ex303 multiplexes the coded video signal and audio signal, and provides the resulting signal outside. When the multiplexing/demultiplexing unit ex303 multiplexes the video signal and the audio signal, the signals may be temporarily stored in the buffers ex320 and ex321 , and others so that the signals are reproduced in synchronization with each other. Here, the buffers ex318, ex319, ex320, and ex321 may be plural as illustrated, or at least one buffer may be shared in the television ex300. Furthermore, data may be stored in a buffer so that the system overflow and underflow may be avoided between the modulation/demodulation unit ex302 and the multiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration for receiving an AV input from a microphone or a camera other than the configuration for obtaining audio and video data from a broadcast or a recording medium, and may code the obtained data. Although the television ex300 can code, multiplex, and provide outside data in the description, it may be capable of only receiving, decoding, and providing outside data but not the coding, multiplexing, and providing outside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexed data from or on a recording medium, one of the television ex300 and the reader/recorder ex218 may decode or code the multiplexed data, and the television ex300 and the reader/recorder ex218 may share the decoding or coding.

As an example, Figure 25 illustrates a configuration of an information reproducing/recording unit ex400 when data is read or written from or on an optical disk. The information reproducing/recording unit ex400 includes constituent elements ex401 , ex402, ex403, ex404, ex405, ex406, and ex407 to be described hereinafter. The optical head ex401 irradiates a laser spot in a recording surface of the recording medium ex215 that is an optical disk to write information, and detects reflected light from the recording surface of the recording medium ex215 to read the information. The modulation recording unit ex402 electrically drives a semiconductor laser included in the optical head ex401 , and modulates the laser light according to recorded data. The reproduction demodulating unit ex403 amplifies a reproduction signal obtained by electrically detecting the reflected light from the recording surface using a photo detector included in the optical head ex401 , and demodulates the reproduction signal by separating a signal component recorded on the recording medium ex215 to reproduce the necessary information. The buffer ex404 temporarily holds the information to be recorded on the recording medium ex215 and the information reproduced from the recording medium ex215. The disk motor ex405 rotates the recording medium ex215. The servo control unit ex406 moves the optical head ex401 to a predetermined information track while controlling the rotation drive of the disk motor ex405 so as to follow the laser spot. The system control unit ex407 controls overall the information reproducing/recording unit ex400. The reading and writing processes can be implemented by the system control unit ex407 using various information stored in the buffer ex404 and generating and adding new information as necessary, and by the modulation recording unit ex402, the reproduction demodulating unit ex403, and the servo control unit ex406 that record and reproduce information through the optical head ex401 while being operated in a coordinated manner. The system control unit ex407 includes, for example, a microprocessor, and executes processing by causing a computer to execute a program for read and write.

Although the optical head ex401 irradiates a laser spot in the description, it may perform high- density recording using near field light.

Figure 26 illustrates the recording medium ex215 that is the optical disk. On the recording surface of the recording medium ex215, guide grooves are spirally formed, and an information track ex230 records, in advance, address information indicating an absolute position on the disk according to change in a shape of the guide grooves. The address information includes information for determining positions of recording blocks ex231 that are a unit for recording data. Reproducing the information track ex230 and reading the address information in an apparatus that records and reproduces data can lead to determination of the positions of the recording blocks. Furthermore, the recording medium ex215 includes a data recording area ex233, an inner circumference area ex232, and an outer circumference area ex234. The data recording area ex233 is an area for use in recording the user data. The inner circumference area ex232 and the outer circumference area ex234 that are inside and outside of the data recording area ex233, respectively are for specific use except for recording the user data. The information reproducing/recording unit 400 reads and writes coded audio, coded video data, or multiplexed data obtained by multiplexing the coded audio and video data, from and on the data recording area ex233 of the recording medium ex215.

Although an optical disk having a layer, such as a DVD and a BD is described as an example in the description, the optical disk is not limited to such, and may be an optical disk having a multilayer structure and capable of being recorded on a part other than the surface. Furthermore, the optical disk may have a structure for multidimensional recording/reproduction, such as recording of information using light of colors with different wavelengths in the same portion of the optical disk and for recording information having different layers from various angles. Furthermore, a car ex210 having an antenna ex205 can receive data from the satellite ex202 and others, and reproduce video on a display device such as a car navigation system ex21 1 set in the car ex210, in the digital broadcasting system ex200. Here, a configuration of the car navigation system ex211 will be a configuration, for example, including a GPS receiving unit from the configuration illustrated in Figure 24. The same will be true for the configuration of the computer ex11 1 , the cellular phone ex114, and others.

Figure 27A illustrates the cellular phone ex1 14 that uses the video coding method and the video decoding method described in embodiments. The cellular phone ex114 includes: an antenna ex350 for transmitting and receiving radio waves through the base station ex1 10; a camera unit ex365 capable of capturing moving and still images; and a display unit ex358 such as a liquid crystal display for displaying the data such as decoded video captured by the camera unit ex365 or received by the antenna ex350. The cellular phone ex114 further includes: a main body unit including an operation key unit ex366; an audio output unit ex357 such as a speaker for output of audio; an audio input unit ex356 such as a microphone for input of audio; a memory unit ex367 for storing captured video or still pictures, recorded audio, coded or decoded data of the received video, the still pictures, e-mails, or others; and a slot unit ex364 that is an interface unit for a recording medium that stores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will be described with reference to Figure 27B. In the cellular phone ex1 14, a main control unit ex360 designed to control overall each unit of the main body including the display unit ex358 as well as the operation key unit ex366 is connected mutually, via a synchronous bus ex370, to a power supply circuit unit ex361 , an operation input control unit ex362, a video signal processing unit ex355, a camera interface unit ex363, a liquid crystal display (LCD) control unit ex359, a modulation/demodulation unit ex352, a multiplexing/demultiplexing unit ex353, an audio signal processing unit ex354, the slot unit ex364, and the memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation, the power supply circuit unit ex361 supplies the respective units with power from a battery pack so as to activate the cell phone ex1 14.

In the cellular phone ex1 14, the audio signal processing unit ex354 converts the audio signals collected by the audio input unit ex356 in voice conversation mode into digital audio signals under the control of the main control unit ex360 including a CPU, ROM, and RAM. Then, the modulation/demodulation unit ex352 performs spread spectrum processing on the digital audio signals, and the transmitting and receiving unit ex351 performs digital-to-analog conversion and frequency conversion on the data, so as to transmit the resulting data via the antenna ex350.

Also, in the cellular phone ex1 14, the transmitting and receiving unit ex351 amplifies the data received by the antenna ex350 in voice conversation mode and performs frequency conversion and the analog-to-digital conversion on the data. Then, the modulation/demodulation unit ex352 performs inverse spread spectrum processing on the data, and the audio signal processing unit ex354 converts it into analog audio signals, so as to output them via the audio output unit ex356.

Furthermore, when an e-mail in data communication mode is transmitted, text data of the e-mail inputted by operating the operation key unit ex366 and others of the main body is sent out to the main control unit ex360 via the operation input control unit ex362. The main control unit ex360 causes the modulation/demodulation unit ex352 to perform spread spectrum processing on the text data, and the transmitting and receiving unit ex351 performs the digital-to-analog conversion and the frequency conversion on the resulting data to transmit the data to the base station ex1 10 via the antenna ex350. When an e-mail is received, processing that is approximately inverse to the processing for transmitting an e-mail is performed on the received data, and the resulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication mode is or are transmitted, the video signal processing unit ex355 compresses and codes video signals supplied from the camera unit ex365 using the video coding method shown in each of embodiments, and transmits the coded video data to the multiplexing/demultiplexing unit ex353. In contrast, during when the camera unit ex365 captures video, still images, and others, the audio signal processing unit ex354 codes audio signals collected by the audio input unit ex356, and transmits the coded audio data to the multiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded video data supplied from the video signal processing unit ex355 and the coded audio data supplied from the audio signal processing unit ex354, using a predetermined method.

Then, the modulation/demodulation unit ex352 performs spread spectrum processing on the multiplexed data, and the transmitting and receiving unit ex351 performs digital-to-analog conversion and frequency conversion on the data so as to transmit the resulting data via the antenna ex350. When receiving data of a video file which is linked to a Web page and others in data communication mode or when receiving an e-mail with video and/or audio attached, in order to decode the multiplexed data received via the antenna ex350, the multiplexing/demultiplexing unit ex353 demultiplexes the multiplexed data into a video data bit stream and an audio data bit stream, and supplies the video signal processing unit ex355 with the coded video data and the audio signal processing unit ex354 with the coded audio data, through the synchronous bus ex370. The video signal processing unit ex355 decodes the video signal using a video decoding method corresponding to the coding method shown in each of embodiments, and then the display unit ex358 displays, for instance, the video and still images included in the video file linked to the Web page via the LCD control unit ex359. Furthermore, the audio signal processing unit ex354 decodes the audio signal, and the audio output unit ex357 provides the audio.

Furthermore, similarly to the television ex300, a terminal such as the cellular phone ex1 14 probably have 3 types of implementation configurations including not only (i) a transmitting and receiving terminal including both a coding apparatus and a decoding apparatus, but also (ii) a transmitting terminal including only a coding apparatus and (iii) a receiving terminal including only a decoding apparatus. Although the digital broadcasting system ex200 receives and transmits the multiplexed data obtained by multiplexing audio data onto video data in the description, the multiplexed data may be data obtained by multiplexing not audio data but character data related to video onto video data, and may be not multiplexed data but video data itself.

As such, the video coding method and the video decoding method in each of embodiments can be used in any of the devices and systems described. Thus, the advantages described in each of embodiments can be obtained.

Furthermore, the present invention is not limited to embodiments, and various modifications and revisions are possible without departing from the scope of the present invention.

Video data can be generated by switching, as necessary, between (i) the video coding method or the video coding apparatus shown in each of embodiments and (ii) a video coding method or a video coding apparatus in conformity with a different standard, such as MPEG-2, H.264/AVC, and VC-1.

Here, when a plurality of video data that conforms to the different standards is generated and is then decoded, the decoding methods need to be selected to conform to the different standards. However, since to which standard each of the plurality of the video data to be decoded conform cannot be detected, there is a problem that an appropriate decoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexing audio data and others onto video data has a structure including identification information indicating to which standard the video data conforms. The specific structure of the multiplexed data including the video data generated in the video coding method and by the video coding apparatus shown in each of embodiments will be hereinafter described. The multiplexed data is a digital stream in the MPEG2-Transport Stream format.

Figure 28 illustrates a structure of the multiplexed data. As illustrated in Figure 28, the multiplexed data can be obtained by multiplexing at least one of a video stream, an audio stream, a presentation graphics stream (PG), and an interactive graphics stream. The video stream represents primary video and secondary video of a movie, the audio stream (IG) represents a primary audio part and a secondary audio part to be mixed with the primary audio part, and the presentation graphics stream represents subtitles of the movie. Here, the primary video is normal video to be displayed on a screen, and the secondary video is video to be displayed on a smaller window in the primary video. Furthermore, the interactive graphics stream represents an interactive screen to be generated by arranging the GUI components on a screen. The video stream is coded in the video coding method or by the video coding apparatus shown in each of embodiments, or in a video coding method or by a video coding apparatus in conformity with a conventional standard, such as MPEG-2, H.264/AVC, and VC-1. The audio stream is coded in accordance with a standard, such as Dolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. For example, 0x101 1 is allocated to the video stream to be used for video of a movie, 0x1100 to 0x111 F are allocated to the audio streams, 0x1200 to 0x121 F are allocated to the presentation graphics streams, 0x1400 to 0x141 F are allocated to the interactive graphics streams, 0x1 B00 to 0x1 B1 F are allocated to the video streams to be used for secondary video of the movie, and 0x1 A00 to 0x1 A1 F are allocated to the audio streams to be used for the secondary video to be mixed with the primary audio.

Figure 29 schematically illustrates how data is multiplexed. First, a video stream ex235 composed of video frames and an audio stream ex238 composed of audio frames are transformed into a stream of PES packets ex236 and a stream of PES packets ex239, and further into TS packets ex237 and TS packets ex240, respectively. Similarly, data of a presentation graphics stream ex241 and data of an interactive graphics stream ex244 are transformed into a stream of PES packets ex242 and a stream of PES packets ex245, and further into TS packets ex243 and TS packets ex246, respectively. These TS packets are multiplexed into a stream to obtain multiplexed data ex247.

Figure 30 illustrates how a video stream is stored in a stream of PES packets in more detail. The first bar in Figure 30 shows a video frame stream in a video stream. The second bar shows the stream of PES packets. As indicated by arrows denoted as yy1 , yy2, yy3, and yy4 in Figure 30, the video stream is divided into pictures as I pictures, B pictures, and P pictures each of which is a video presentation unit, and the pictures are stored in a payload of each of the PES packets. Each of the PES packets has a PES header, and the PES header stores a Presentation Time-Stamp (PTS) indicating a display time of the picture, and a Decoding Time- Stamp (DTS) indicating a decoding time of the picture.

Figure 31 illustrates a format of TS packets to be finally written on the multiplexed data. Each of the TS packets is a 188-byte fixed length packet including a 4-byte TS header having information, such as a PID for identifying a stream and a 184-byte TS payload for storing data. The PES packets are divided, and stored in the TS payloads, respectively. When a BD ROM is used, each of the TS packets is given a 4-byte TP_Extra_Header, thus resulting in 192-byte source packets. The source packets are written on the multiplexed data. The TP_Extra_Header stores information such as an Arrival_Time_Stamp (ATS). The ATS shows a transfer start time at which each of the TS packets is to be transferred to a PID filter. The source packets are arranged in the multiplexed data as shown at the bottom of Figure 31. The numbers incrementing from the head of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes not only streams of audio, video, subtitles and others, but also a Program Association Table (PAT), a Program Map Table (PMT), and a Program Clock Reference (PCR). The PAT shows what a PID in a PMT used in the multiplexed data indicates, and a PID of the PAT itself is registered as zero. The PMT stores PIDs of the streams of video, audio, subtitles and others included in the multiplexed data, and attribute information of the streams corresponding to the PIDs. The PMT also has various descriptors relating to the multiplexed data. The descriptors have information such as copy control information showing whether copying of the multiplexed data is permitted or not. The PCR stores STC time information corresponding to an ATS showing when the PCR packet is transferred to a decoder, in order to achieve synchronization between an Arrival Time Clock (ATC) that is a time axis of ATSs, and an System Time Clock (STC) that is a time axis of PTSs and DTSs.

Figure 32 illustrates the data structure of the PMT in detail. A PMT header is disposed at the top of the PMT. The PMT header describes the length of data included in the PMT and others. A plurality of descriptors relating to the multiplexed data is disposed after the PMT header. Information such as the copy control information is described in the descriptors. After the descriptors, a plurality of pieces of stream information relating to the streams included in the multiplexed data is disposed. Each piece of stream information includes stream descriptors each describing information, such as a stream type for identifying a compression codec of a stream, a stream PID, and stream attribute information (such as a frame rate or an aspect ratio). The stream descriptors are equal in number to the number of streams in the multiplexed data.

When the multiplexed data is recorded on a recording medium and others, it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management information of the multiplexed data as shown in Figure 33. The multiplexed data information files are in one to one correspondence with the multiplexed data, and each of the files includes multiplexed data information, stream attribute information, and an entry map.

As illustrated in Figure 33, the multiplexed data includes a system rate, a reproduction start time, and a reproduction end time. The system rate indicates the maximum transfer rate at which a system target decoder to be described later transfers the multiplexed data to a PID filter. The intervals of the ATSs included in the multiplexed data are set to not higher than a system rate. The reproduction start time indicates a PTS in a video frame at the head of the multiplexed data. An interval of one frame is added to a PTS in a video frame at the end of the multiplexed data, and the PTS is set to the reproduction end time.

As shown in Figure 34, a piece of attribute information is registered in the stream attribute information, for each PID of each stream included in the multiplexed data. Each piece of attribute information has different information depending on whether the corresponding stream is a video stream, an audio stream, a presentation graphics stream, or an interactive graphics stream. Each piece of video stream attribute information carries information including what kind of compression codec is used for compressing the video stream, and the resolution, aspect ratio and frame rate of the pieces of picture data that is included in the video stream. Each piece of audio stream attribute information carries information including what kind of compression codec is used for compressing the audio stream, how many channels are included in the audio stream, which language the audio stream supports, and how high the sampling frequency is. The video stream attribute information and the audio stream attribute information are used for initialization of a decoder before the player plays back the information.

The multiplexed data to be used is of a stream type included in the PMT. Furthermore, when the multiplexed data is recorded on a recording medium, the video stream attribute information included in the multiplexed data information is used. More specifically, the video coding method or the video coding apparatus described in each of embodiments includes a step or a unit for allocating unique information indicating video data generated by the video coding method or the video coding apparatus in each of embodiments, to the stream type included in the PMT or the video stream attribute information. With the configuration, the video data generated by the video coding method or the video coding apparatus described in each of embodiments can be distinguished from video data that conforms to another standard.

Furthermore, Figure 35 illustrates steps of the video decoding method. In Step exS100, the stream type included in the PMT or the video stream attribute information is obtained from the multiplexed data. Next, in Step exS101 , it is determined whether or not the stream type or the video stream attribute information indicates that the multiplexed data is generated by the video coding method or the video coding apparatus in each of embodiments. When it is determined that the stream type or the video stream attribute information indicates that the multiplexed data is generated by the video coding method or the video coding apparatus in each of embodiments, in Step exS102, decoding is performed by the video decoding method in each of embodiments. Furthermore, when the stream type or the video stream attribute information indicates conformance to the conventional standards, such as MPEG-2, H.264/AVC, and VC-1 , in Step exS103, decoding is performed by a video decoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the video stream attribute information enables determination whether or not the video decoding method or the video decoding apparatus that is described in each of embodiments can perform decoding. Even when multiplexed data that conforms to a different standard, an appropriate decoding method or apparatus can be selected. Thus, it becomes possible to decode information without any error. Furthermore, the video coding method or apparatus, or the video decoding method or apparatus can be used in the devices and systems described above. Each of the video coding method, the video coding apparatus, the video decoding method, and the video decoding apparatus in each of embodiments is typically achieved in the form of an integrated circuit or a Large Scale Integrated (LSI) circuit. As an example of the LSI, Figure 36 illustrates a configuration of the LSI ex500 that is made into one chip. The LSI ex500 includes elements ex501 , ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to be described below, and the elements are connected to each other through a bus ex510. The power supply circuit unit ex505 is activated by supplying each of the elements with power when the power supply circuit unit ex505 is turned on.

For example, when coding is performed, the LSI ex500 receives an AV signal from a microphone ex1 17, a camera ex113, and others through an AV IO ex509 under control of a control unit ex501 including a CPU ex502, a memory controller ex503, a stream controller ex504, and a driving frequency control unit ex512. The received AV signal is temporarily stored in an external memory ex51 1 , such as an SDRAM. Under control of the control unit ex501 , the stored data is segmented into data portions according to the processing amount and speed to be transmitted to a signal processing unit ex507. Then, the signal processing unit ex507 codes an audio signal and/or a video signal. Here, the coding of the video signal is the coding described in each of embodiments. Furthermore, the signal processing unit ex507 sometimes multiplexes the coded audio data and the coded video data, and a stream IO ex506 provides the multiplexed data outside. The provided multiplexed data is transmitted to the base station ex107, or written on the recording media ex215. When data sets are multiplexed, the data should be temporarily stored in the buffer ex508 so that the data sets are synchronized with each other.

Although the memory ex51 1 is an element outside the LSI ex500, it may be included in the LSI ex500. The buffer ex508 is not limited to one buffer, but may be composed of buffers. Furthermore, the LSI ex500 may be made into one chip or a plurality of chips.

Furthermore, although the control unit ex510 includes the CPU ex502, the memory controller ex503, the stream controller ex504, the driving frequency control unit ex512, the configuration of the control unit ex510 is not limited to such. For example, the signal processing unit ex507 may further include a CPU. Inclusion of another CPU in the signal processing unit ex507 can improve the processing speed. Furthermore, as another example, the CPU ex502 may serve as or be a part of the signal processing unit ex507, and, for example, may include an audio signal processing unit. In such a case, the control unit ex501 includes the signal processing unit ex507 or the CPU ex502 including a part of the signal processing unit ex507. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and a special circuit or a general purpose processor and so forth can also achieve the integration. Field Programmable Gate Array (FPGA) that can be programmed after manufacturing LSIs or a reconfigurable processor that allows re-configuration of the connection or configuration of an LSI can be used for the same purpose.

In the future, with advancement in semiconductor technology, a brand-new technology may replace LSI. The functional blocks can be integrated using such a technology. The possibility is that the present invention is applied to biotechnology.

When video data generated in the video coding method or by the video coding apparatus described in each of embodiments is decoded, compared to when video data that conforms to a conventional standard, such as MPEG-2, H.264/AVC, and VC-1 is decoded, the processing amount probably increases. Thus, the LSI ex500 needs to be set to a driving frequency higher than that of the CPU ex502 to be used when video data in conformity with the conventional standard is decoded. However, when the driving frequency is set higher, there is a problem that the power consumption increases.

In order to solve the problem, the video decoding apparatus, such as the television ex300 and the LSI ex500 is configured to determine to which standard the video data conforms, and switch between the driving frequencies according to the determined standard. Figure 37 illustrates a configuration ex800. A driving frequency switching unit ex803 sets a driving frequency to a higher driving frequency when video data is generated by the video coding method or the video coding apparatus described in each of embodiments. Then, the driving frequency switching unit ex803 instructs a decoding processing unit ex801 that executes the video decoding method described in each of embodiments to decode the video data. When the video data conforms to the conventional standard, the driving frequency switching unit ex803 sets a driving frequency to a lower driving frequency than that of the video data generated by the video coding method or the video coding apparatus described in each of embodiments. Then, the driving frequency switching unit ex803 instructs the decoding processing unit ex802 that conforms to the conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includes the CPU ex502 and the driving frequency control unit ex512 in Figure 36. Here, each of the decoding processing unit ex801 that executes the video decoding method described in each of embodiments and the decoding processing unit ex802 that conforms to the conventional standard corresponds to the signal processing unit ex507 in Figure 34. The CPU ex502 determines to which standard the video data conforms. Then, the driving frequency control unit ex512 determines a driving frequency based on a signal from the CPU ex502. Furthermore, the signal processing unit ex507 decodes the video data based on the signal from the CPU ex502. For example, the identification information described is probably used for identifying the video data. The identification information is not limited to the one described above but may be any information as long as the information indicates to which standard the video data conforms. For example, when which standard video data conforms to can be determined based on an external signal for determining that the video data is used for a television or a disk, etc., the determination may be made based on such an external signal. Furthermore, the CPU ex502 selects a driving frequency based on, for example, a look-up table in which the standards of the video data are associated with the driving frequencies as shown in Figure 39. The driving frequency can be selected by storing the look-up table in the buffer ex508 and in an internal memory of an LSI, and with reference to the look-up table by the CPU ex502.

Figure 38 illustrates steps for executing a method. First, in Step exS200, the signal processing unit ex507 obtains identification information from the multiplexed data. Next, in Step exS201 , the CPU ex502 determines whether or not the video data is generated by the coding method and the coding apparatus described in each of embodiments, based on the identification information. When the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, in Step exS202, the CPU ex502 transmits a signal for setting the driving frequency to a higher driving frequency to the driving frequency control unit ex512. Then, the driving frequency control unit ex512 sets the driving frequency to the higher driving frequency. On the other hand, when the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, H.264/AVC, and VC-1 , in Step exS203, the CPU ex502 transmits a signal for setting the driving frequency to a lower driving frequency to the driving frequency control unit ex512. Then, the driving frequency control unit ex512 sets the driving frequency to the lower driving frequency than that in the case where the video data is generated by the video coding method and the video coding apparatus described in each of embodiment.

Furthermore, along with the switching of the driving frequencies, the power conservation effect can be improved by changing the voltage to be applied to the LSI ex500 or an apparatus including the LSI ex500. For example, when the driving frequency is set lower, the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set to a voltage lower than that in the case where the driving frequency is set higher.

Furthermore, when the processing amount for decoding is larger, the driving frequency may be set higher, and when the processing amount for decoding is smaller, the driving frequency may be set lower as the method for setting the driving frequency. Thus, the setting method is not limited to the ones described above. For example, when the processing amount for decoding video data in conformity with H.264/AVC is larger than the processing amount for decoding video data generated by the video coding method and the video coding apparatus described in each of embodiments, the driving frequency is probably set in reverse order to the setting described above.

Furthermore, the method for setting the driving frequency is not limited to the method for setting the driving frequency lower. For example, when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set higher. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, H.264/AVC, and VC-1 , the voltage to be applied to the LSI ex500 or the apparatus including the LSI ex500 is probably set lower. As another example, when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, the driving of the CPU ex502 does not probably have to be suspended. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, H.264/AVC, and VC-1 , the driving of the CPU ex502 is probably suspended at a given time because the CPU ex502 has extra processing capacity. Even when the identification information indicates that the video data is generated by the video coding method and the video coding apparatus described in each of embodiments, in the case where the CPU ex502 has extra processing capacity, the driving of the CPU ex502 is probably suspended at a given time. In such a case, the suspending time is probably set shorter than that in the case where when the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, H.264/AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switching between the driving frequencies in accordance with the standard to which the video data conforms. Furthermore, when the LSI ex500 or the apparatus including the LSI ex500 is driven using a battery, the battery life can be extended with the power conservation effect. There are cases where a plurality of video data that conforms to different standards, is provided to the devices and systems, such as a television and a mobile phone. In order to enable decoding the plurality of video data that conforms to the different standards, the signal processing unit ex507 of the LSI ex500 needs to conform to the different standards. However, the problems of increase in the scale of the circuit of the LSI ex500 and increase in the cost arise with the individual use of the signal processing units ex507 that conform to the respective standards.

In order to solve the problem, what is conceived is a configuration in which the decoding processing unit for implementing the video decoding method described in each of embodiments and the decoding processing unit that conforms to the conventional standard, such as MPEG-2, H.264/AVC, and VC-1 are partly shared. Ex900 in Figure 40A shows an example of the configuration. For example, the video decoding method described in each of embodiments and the video decoding method that conforms to H.264/AVC have, partly in common, the details of processing, such as entropy coding, inverse quantization, deblocking filtering, and motion compensated prediction. The details of processing to be shared may include use of a decoding processing unit ex902 that conforms to H.264/AVC. In contrast, a dedicated decoding processing unit ex901 is probably used for other processing unique to the present invention. Since the present invention is characterized by encoding of filtering data and embedding it in the bitstream together with the encoded slice data, for example, the dedicated decoding processing unit ex901 is used for such encoding. Otherwise, the decoding processing unit is probably shared for one of the entropy decoding, inverse quantization, spatial or motion compensated prediction, or all of the processing. The decoding processing unit for implementing the video decoding method described in each of embodiments may be shared for the processing to be shared, and a dedicated decoding processing unit may be used for processing unique to that of H.264/AVC.

Furthermore, ex1000 in Figure 40B shows another example in that processing is partly shared. This example uses a configuration including a dedicated decoding processing unit ex1001 that supports the processing unique to the present invention, a dedicated decoding processing unit ex1002 that supports the processing unique to another conventional standard, and a decoding processing unit ex1003 that supports processing to be shared between the video decoding method in the present invention and the conventional video decoding method. Here, the dedicated decoding processing units ex1001 and ex1002 are not necessarily specialized for the processing of the present invention and the processing of the conventional standard, respectively, and may be the ones capable of implementing general processing. Furthermore, the configuration can be implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing the cost are possible by sharing the decoding processing unit for the processing to be shared between the video decoding method in the present invention and the video decoding method in conformity with the conventional standard.

Most of the examples have been outlined in relation to an H.264/AVC based video coding system, and the terminology mainly relates to the H.264/AVC terminology. However, this terminology and the description of the various embodiments with respect to H.264/AVC based coding is not intended to limit the principles and ideas of the invention to such systems. Also the detailed explanations of the encoding and decoding in compliance with the H.264/AVC standard are intended to better understand the exemplary embodiments described herein and should not be understood as limiting the invention to the described specific implementations of processes and functions in the video coding. Nevertheless, the improvements proposed herein may be readily applied in the video coding described. Furthermore the concept of the invention may be also readily used in the enhancements of H.264/AVC coding and/or HEVC currently discussed by the JCT-VC.

Summarizing, the present invention relates to bitstream organization, coding and decoding of the image data including filtering parameters. In particular, according to the present invention the slices of images and the filtering parameters relating to filtering of the respective slices are encoded and decoded independently of each other. Moreover, the filtering is located in the bitstream before (in front of) the data including slice image data even when the coding of the slice data and the filtering data is performed in a reverse order.

Claims

1. A method for encoding slices of image data into a bitstream including the steps of: encoding a slice of image data with a variable length code; estimating parameters for in-loop filtering the slice of image data; encoding the estimated parameters with a variable length code, wherein the encoding of the slice of image data and the encoding of the estimated parameters are performed independently of each other; and inserting the encoded parameters into the bitstream before the encoded slice of image data.

2. A method for decoding slices of image data from a bitstream including the steps of: extracting from the bitstream encoded parameters and then an encoded slice of image data which follows the encoded parameters in the bitstream; decode the encoded parameters for in-loop filtering of the slice of the image data using a variable length code, decode the slice of image data using a variable length code, wherein the decoding of the slice of image data and the decoding of the encoded parameters are performed independently of each other.

3. The method according to claim 1 or 2, wherein the variable length code applied for encoding of the slice of image data is arithmetic code.

4. The method according to any of claims 1 to 3, wherein the variable length code applied for encoding of the estimated parameters is a code other than arithmetic code.

5. The method according to any of claims 1 to 4, wherein the in-loop filtering is an adaptive loop filtering and/or sample adaptive offset.

6. The method according to any of claims 1 to 5, wherein the bitstream comprises a slice header followed by the encoded slice data and the estimated parameters are included in a separate parameter set.

7. The method according to any of claims 1 to 6, wherein the estimated parameters include at least one of a flag for signaling whether a filtering is to be applied to the slice of data, a filter indicator for indicating which the filter is to be used for filtering of the slice data, offset, and filter coefficients.

8. The method according to claim 6, wherein the separate parameter set contains only the estimated parameters of the adaptive loop filter and forms alone the content of a separate network adaptation unit.

9. A computer program product comprising a computer-readable medium having a

computer-readable program code embodied thereon, the computer program code being adapted to carry out the steps of any of claims 1 to 8.

10. An apparatus for encoding slices of image data into a bitstream including: an image data encoder for encoding a slice of image data with a variable length code; an estimator for estimating parameters for in-loop filtering the slice of image data; a control data encoder for encoding the estimated parameters with a variable length code, wherein the encoding of the slice of image data and the encoding of the estimated parameters are performed independently of each other; and a bitsrtream generator for inserting the encoded parameters into the bitstream before the encoded slice of image data.

11. An apparatus for decoding slices of image data from a bitstream including: a bitstream parser for extracting from the bitstream encoded parameters and then encoded slice of a slice of image data which follow the encoded parameters in the bitstream; a control data decoder for decoding the encoded parameters for in-loop filtering of the slice of the image data using a variable length code; an image data decoder for decode the slice of image data sing a variable length code; wherein the apparatus is adapted to perform the decoding of the slice of image data and the decoding of the estimated parameters independently of each other.

12. The apparatus according to claim 10 or 11 , wherein the variable length code applied to the slice of image data is arithmetic code.

13. The apparatus according to any of claims 10 to 12 wherein the variable length code applied to the estimated parameters is a code other than arithmetic code.

14. The apparatus according to any of claims 10 to 13, wherein the in-loop filtering is an adaptive loop filtering and/or sample adaptive offset.

15. The apparatus according to any of claims 10 to 14, wherein the bitstream comprises a slice header followed by the encoded slice data and the estimated parameters are included in a separate parameter set.

16. The apparatus according to any of claims 10 to 15, wherein the estimated parameters include at least one of a flag for signaling whether a filtering is to be applied to the slice of data, a filter indicator for indicating which the filter is to be used for filtering of the slice data, offset and filter coefficients.

17. The apparatus according to claim 15, wherein the separate parameter set contains only the estimated parameters of the adaptive loop filter and forms alone the content of a separate network adaptation unit.