MXPA00008746A - Method and apparatus for encoding a video signal - Google Patents

Abstract

A video signal encoder codes a video signal including texture information and shape information on each of macroblocks, a macroblock having 16x16 pixels and being dividable into 4 numbers of equal-sized DCT-blocks. The encoder produces encoded shape information by encoding the shape information on a processing macroblock and generates a reconstructed shape information by decoding the encoded shape information. Then, a DCT_type of the processing macroblock is determined based on the reconstructed shape information and the texture information on the processing macroblock to thereby provide DCT_type information representing the DCT_type. Once the DCT_type of the processing macroblock is decided, the encoder generates encoded texture information by adaptively encoding the texture information through the use of a progressive or an interlaced coding technique in response to the DCT_type information. Furthermore, the encoder generates CBPY information by using the encoding results of the texture information and provides a data stream to be transmitted in sequence of the encoded shape information, the encoded CBPY information, the DCT_type information and the encoded texture information.

Description

METHOD AND APPARATUS FOR CODING A VIDEO SIGNAL Technical Field of the Invention The present invention relates to a method and an apparatus for encoding a video signal; and more particularly to a method and apparatus for effectively encoding texture information of the video signal by determining a type of encoding of the texture information, based on the texture information and its information responsively. Prior Art In digital video systems such as video telephone and teleconferencing systems, a large amount of digital data is required to define each video signal since the video signal comprises a sequence of digital data referred to as pixel values. Since, however, the available frequency bandwidth of a conventional transmission channel is limited, in order to transmit the substantial amount of digital data through it, it is necessary to compress or reduce the volume of data through the use of various data compression techniques, especially in the case of low bit rate video signal encoders such as telephone video and teleconferencing systems. One of these techniques for encoding video signals for a low bit rate coding system is a coding technique with object oriented analysis synthesis, wherein a feed video image is divided into objects and three sets of parameters for Define movement, contour and pixel data of each object that are processed through different coding channels. An example of these object-oriented coding schemes is the so-called Moving Picture Express Group (MPEG), which is designed to provide a standard audio visual coding standard for allow content-based interactivity, improved coding efficiency and universal accessibility in applications such as low bit-rate communication, interactive multimedia (eg games, interactive TV, etc.) and area surveillance (see for example MPEG-4 Video Verification Model Version 7.0, International Organization for Standardization, Coding of Moving Pictures and Associated Audio Information (Video Verification Model MPEG-4 version 7.0, International Organization for Standardization, Coding of Moving Images and Associated Audio Information ISO / IEC JTC1 / SC29 / WG11 MPEG97 / N1642, Bristol, April 1997.) According to the MPE-4, a food video image of This is divided into a plurality of video object planes (VOP's = Video Object Planes), which correspond to entities in a stream of bits that a user can access and manipulate. A VOP can be represented by a border rectangle whose width and height can be the smallest multiples of 16 pixels (a size of macro blocks) that surrounds each object, so that the encoder processes the video image fed into a VOP base. por-VOP. A VOP described in MPEG-4 includes shape information and texture information for an object that is represented by a plurality of macro blocks in the VOP, each of the macro blocks having for example 16 x 16 pixels. Each of the macro blocks in the VOP can be classified into one of macro background, border, and object blocks. The macro background block contains only background pixels located outside of an object in the VOP; the macro border block includes at least one background pixel and at least one object pixel located within the object; and the macro object block only has pixels of objects.

The form information is encoded by using for example an arithmetic coding technique based on context (CAE = Context-based Arithmetic Encoding) and on a macro block basis and texture information is encoded through the use of conventional coding techniques such as transform the discrete cosine (DCT = Discrete Cosine Transform); quantification techniques and VLC and variable length coding (VLC = Variable Length Coding) based on macro block. Specifically, the DCT process for transforming the texture information is done in a DCT block base, where a macro block is divided into four DCT blocks of 8 x 8 pixels. Of the quantification and DCT processes, a DC component and a multiplicity of AC components are produced for each DCT block. However, if all the texture information values for a DCT block are constant, there is no corresponding non-zero AC component for the DCT block, therefore, coded block pattern type information (CBPY = coded block: pattern type ) has been proposed to represent either whether a DCT block has at least one corresponding non-zero AC component. To be more specific if there is at least one non-zero AC component corresponding to a DCT block, the CBPY information obtains a bit, for example from "1" and if it is otherwise, a bit of for example "0". According to this, a coding part can distinguish the existence of non-zero AC components for a corresponding DCT block by simply detecting the CBPY information transmitted through a transmission channel without any additional information for the corresponding DCT block and before that. the texture information encoded for the corresponding DCT block is transmitted to it. Conventionally, in order to encode the texture information for the VOP, the texture information in each of the macro blocks is processed by adaptively using interlaced and progressive coding techniques to improve coding efficiency. Therefore, the DCT type information (DCT__type) which represents a coding condition, ie a DCT_type of the texture information is used and the DCT_type is determined on a macro block basis using the texture information. For example, a video signal encoder determines an appropriate DCT_type for a macro block, when comparing a spatial correlation in first of pixels in the macro block that are reconstituted to a progressive or interlaced macro block according to the technique of progressive or interlaced coding. If the progressive coding technique is determined to be more effective, the DCT_type information in the macro block will have a bit of, for example "0" and if it is otherwise, a bit for example of "1". After the DCT_type for a macro block is determined based on the texture information, the CBPY information in the macro block is obtained from quantified DCT results that are derived when performing the quantization and DCT processes for the texture information in the macro block in your DCT_type determined. For example, if a macro background block, its texture information is not verified and therefore, its DCT_type and CBPY information are not generated. If the macro block is a macro object block, either the progressive or interlaced coding technique can be selected based on the texture information in the macro block and therefore the DCT_type information of the macro object block representing the selected coding technique , it is produced. Also, the CBPY information of the macro object block will have four bit data, the respective bits correspond to the four respective DCT blocks within the macro block, since the macro object block has four non-transparent DCT blocks, where a non-transparent DCT block It has a DCT block size and contains at least one object pixel to be encoded. On the other hand, if the macro block is a macro border block, either the progressive or interlaced coding technique is also selected based on the texture information in the macro block. In addition, the macro border block can include both the transparent DCT block and a non-transparent DCT block as a whole, where the transparent DCT block only has background pixels there and does not need to be encoded. Consequently, the CBPY information corresponding to the macro border block can have i-bit data, and is a positive integer in the range of 1 to 4, and the respective bits correspond to the respective non-transparent DCT blocks in the macro block. With reference to Figures 4A to 4C, several examples of macro border blocks are provided which are classified into two different types, i.e. macro blocks of interleaved and progressive types. In the drawings, the macro blocks Pl to P3 representing macro blocks of progressive types respectively are reformed into macro blocks of interlaced type II to 13 including upper and background field DCT blocks IT1 and IB1 to IT3 and IB3, respectively. Therefore, in the progressive coding technique, the macro block is encoded based on the progressive-type macro block while it is encoded by using the interlaced-type macro block including the upper-field and background DCT blocks in the art. of interlaced coding. As can be seen in Figure 4A, since both the progressive-type macro block Pl and its interlaced-type macro block II contain only non-transparent DCT blocks, the corresponding CBPY information has four-bit data independently of the DCT_type of the macro-block. However, in Figures 4B and C, the non-transparent DCT block numbers within macro interlaced and progressive type blocks are different from each other depending on their DCT_type. Consequently, the number of bits of the CBPY information are also changed according to the DCT__type. To be more specific, when the macro block P2 is encoded through the progressive coding technique, the two-bit CBPY information is generated and otherwise four-bit CBPY information is produced. Meanwhile, when the macro block P3 is encoded through the progressive coding technique, the two-bit CBPY information is generated and otherwise the one-bit CBPY information is produced. As can be noted above, if a macro block to be processed is a macro block border, the number of bits of the CBPY information, ie the number of non-transparent DCT blocks, is determined depending on DCT_type. However, in the above conventional coding method which uses the information DCT_type and CBPY, a data stream to be transmitted to the decoding part has a sequence as illustrated in Figure 5. That is, the information in encoded form is transmitted first to the decoding part and the other encoded information follows the information in a coded form in the information order CBPY, DCT_type and texture. Therefore, when the decoding part receives the information encoded in the above sequence and a processed macro block is a macro border block, the decoding part can not correctly predict the number of the CBPY information, ie the number of DCT blocks non-transparent within the processed macro block and consequently can not accurately reconstruct the CBPY information since the CBPY information has been determined dependent on the DCT_type information that is transmitted to the decoding part after the encoded CBPY information. DESCRIPTION OF THE INVENTION Therefore, a primary objective of the invention is to provide a method and an apparatus for use in a video signal encoder, to encode texture information of a video signal by using its information correspondingly in addition to the texture information. In accordance with one aspect of the present invention, there is provided a method, for use in the video signal encoder, for encoding texture information of a video signal that includes the texture information and shape information in each of the macro blocks, each macro block has MxM pixels and is divisible by the number P of DCT blocks of equal size, M and P are positive integers, respectively, comprising the steps of: (a) determining a DCT_type of a macro processing block based on shape information and texture information in the macro processing block, where the DCT_type represents the most coding technique effective between a progressive encoding technique and interlaced decoding, to encode texture information; and (b) generating texture information by adaptive coding of the texture information through the use of the progressive coding technique or the interlaced coding technique, in response to the DCT_type. According to another aspect of the present invention, there is provided an apparatus for encoding a video signal that includes texture information and shape information for each of the macro blocks, each macro block has MxM pixels and is divisible by the P number. of DCT blocks of equal size, M and P are positive integers respectively, comprising: a shape encoder for producing information in encoded form by encoding shape information for a macro processing block and generating information in reconstructed form upon decoding the information of encoded form; a unit for DCT_type determination to decide a DCT_type of the macro processing block based on the reconstructed shape information and the texture information for the macro processing block and provide the DCT_type information representing the DCT_type, where the DCT_type represents the more effective coding technique between progressive and interlaced coding techniques for encoding texture information; and a texture encoder for generating coded texture information by adaptively encoding the texture information through the use of the progressive coding or interlaced coding technique in response to the DCT_type information. BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and features of the present invention will be apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings in which: Figure 1 depicts a block diagram of a video signal encoder in accordance with a first embodiment of the present invention; Figure 2 provides a block diagram of the video signal encoder according to a second embodiment of the present invention; Figure 3 presents a detailed block diagram of the modified DCT unit 130 of Figure 1; Figures 4A and 4C describe examples of macro border blocks that are classified into two different types; and Figure 5 shows a sequence of a data stream to be transmitted to a decoding part. MODES FOR CARRYING OUT THE INVENTION A video signal includes shape information and texture information in a plurality of macro blocks and according to embodiments of the present invention, the texture information is adaptively encoded on a macro block basis through the use of either a progressive or interlaced coding technique. Each of the macro blocks has MxM for example 16 x 16 pixels and can be divided into four DCT blocks having the same number of pixels, for example 8 8 pixels, M is a positive integer. According to the present invention, an appropriate coding technique, i.e. either the progressive or interlaced coding technique, for each of the macro blocks, is determined based on texture and shape information while it has been determined by using only the texture information in the conventional coding method.

With reference to Figure 1, a block diagram of a video signal encoder 10 according to a first embodiment of the present invention is provided. The texture information in a macro processing block is fed to a unit for determining DCT_type 120 and to a modified DCT unit 130 in parallel and its information is correspondingly coupled to a form 110 encoder. The shape encoder 110 encodes the shape information by using a coding method in known manner, for example the CAE technique described in MEPG-4, to thereby generate information in coded form and provide the information in a coded form to a multiplexer (MUX) 190 by means of a line L12. The shape encoder 110 also provides reconstructed form information in the processing macro block that is generated by decoding the information in coded form, to a form inspection unit 110 and the modified DCT unit 130 by a parallel IOL line. The form inspection unit 100 determines a block type of the macro processing block based on the information of reconstructed form, where the block type includes a macro background block, an object macro and a border macro. The macro background block is made up only of background pixels; the macro object block includes only object pixels; and the macro border block contains at least one pixel object and at least one background pixel together. If the block type of the processing block macro is determined, the form inspection unit 100 provides a block indication signal, the block type of the processing block macro representing the DCT_type 120 determination unit. determination of DCT_type 120 decides a DCT_type of the macro processing block, in response to the texture information in the macro processing block and the indication signal of a block derived from the inspection unit of form 100. That is, if the signal block indication represents the macro border block as an exemplary shape shown in Figures 4A to 4C, the determination unit DCT_type 120 produces a progressive coding indication signal independent of the texture information and provides the progressive coding indication signal only to the modified DCT unit 130 via a line L16. If the block indication signal represents the macro block object, the determination unit DCT_type the DCT_type of the macro processing block by using a known DCT_type determination method based on the texture information and then supplying DCT_type information representing the DCT_type of the processing macro to the MUX 190 by means of a line L14 and the modified DCT unit 130 via line L16. If the block indication signal illustrates the background macro block, the DCT_type determination unit 120 provides a DCT deactivation signal to the modified DCT unit 130 on line L16. In response to the deactivated signal being fed to it, the modified DCT unit 130 stops to perform a DCT process for the background macro block.

That is, the modified DCT unit 130 does not operate due to the DCT deactivation signal that is fed to it. On the other hand, in a conventional coding method, if the macro processing block is determined as the background macro block, the video signal encoder 10 does not perform any processing for the background macro block since its corresponding texture information it is not coupled to the video signal encoder 10. If either of the progressive coding indication signal or the DCT_type information for the macro block is fed, the modified DCT unit 130 produces a set of DCT coefficients for a non-transparent DCT block, by performing a conventional DCT method based on texture and reconstructed shape information in the macro processing block, wherein the non-transparent DCT block has a DCT block size and contains at least one object pixel. Meanwhile, as mentioned above, if the deactivation signal is fed to it, the modified DCT unit 130 does not perform any process and there is no output. According to the first embodiment of the present invention, with reference to Figure 3, a detailed block diagram of the modified DCT unit 130 is provided including a shape reconstitution sector 132, a texture reconstitution sector 134, a sector selection 136 and a DCT sector 138. If the progressive coding indication signal or DCT__type information representing the type of progressive coding is coupled via line L16, the form reconstitution sector 132 directly transfers the information in reconstructed form which is provided from the form coder 110 to the selection sector 136. On the other hand, the form reconstitution sector 132 provides information in reconstituted form generated by reconstituting the information in reconstituted form according to the coding technique interlaced with the sector of selection 136 if the DCT_type information that represents the type of coding entwined is fed. Similarly, if the progressive coding indication signal or the DCT_type information representing the progressive encoding type is coupled by the line L16, the texture reconstitution sector 134 directly supplies the texture information that is coupled to the selection sector 136. On the other hand, the texture reconstitution sector 134 provides reconstituted texture information that is produced by reconstituting the texture information according to the entanglement coding technique to the selection sector 136 if the DCT__type information representing the interlaced type of coding. he is fed. Previously, if the deactivated signal is fed by line L16, the shape and texture reconstitution sectors 132 and 134 do not operate. The selection sector 136 detects at least one non-transparent DCT block between DCT blocks in the progressive block macro or the interleaved macro corresponding to the macro processing block based on the reconstructed or reconstituted information that is provided from the sector form reconstitution 132. Then, the selection sector 136 provides the texture or reconstituted texture information corresponding to each of the non-transparent DCT blocks to the DCT 138 sector. The DCT 138 sector converts the texture or the reconstituted texture information corresponding to each of the non-transparent blocks in a set of DCT coefficients and transfers the set of coefficients DCT to a quantization unit (Q) 135 in Figure 1. Next, the processes performed in the modified DCT unit 130 will be illustrated more descriptively according to the DCT_type of the macro processing block. If the DCT_type information is fed, ie the macro processing block is determined as the macro object block, since the macro object block has four non-transparent DCT blocks as illustrated in the prior art, the modified DCT unit 130 converts the texture information corresponding to the macro processing block, which is reconstituted in response to the DCT_type information, to four sets of DCT coefficients and the four sets of DCT coefficients are fed sequentially to the unit Q 135. Previously, if the progressive coding technique is chosen to code the processing macro block, the texture information in the progressive type macro block is transformed into DCT coefficients in the modified DCT unit 130 based on the DCT block. On the other hand, if the interlaced coding technique is chosen, the texture information in the field DCT blocks is converted into DCT coefficients in the base of DCT blocks. Meanwhile, if the progressive coding indication signal is coupled to it, the modified DCT unit 130 converts the texture information into each of the non-transparent DCT blocks, which are determined based on the reconstructed form information within the macro block. of DCT coefficients processing. The DCT process for the macro border block will be illustrated with reference to Figures 4A to 4C which provide examples of the macro border blocks classified into two different types, i.e. the macro blocks of progressive and interlaced type. For simplicity of explanation, consider that each of the macro border blocks in Figures 4A through 4C is derived from the reconstructed shape information that is provided from the form encoder 110. In accordance with the first embodiment of the present invention, since the macro border block is processed only by the progressive coding technique and the modified DCT unit 130 performs the DCT process for non-transparent DCT blocks, the texture information corresponding to each of the macro blocks of the progressive type Pl to P3 in the Figures 4A to 4C are transformed into the modified DCT unit 130. In Figure 4A, since the progressive block macro PI only has non-transparent DCT blocks, the texture information in the macro processing block becomes four sets of the coefficients DCT in the modified DCT unit 130. On the other hand, since P2 and P3 have two non-transparent DCT blocks and two non-transparent DCT blocks, respectively , the texture information corresponding to each of the two non-transparent DCT blocks is converted into a set of DCT coefficients. Again with reference to Figure 1, as mentioned above, the DCT coefficient sets produced in the modified DCT unit 130 are sequentially supplied to the Q 135 unit. The Q 135 unit quantizes a set of DCT coefficients that are provided from the modified DCT unit 130 and provides a set of quantized DCT coefficients to a statistical coding unit 180 and a component detection unit C 140. The statistical coding unit 180 produces coded texture information by compressing the set of quantized DCT coefficients which are derived from the unit Q 135 through the use of, for example, a variable length coding technique and provides the coded texture information to the MUX 190. The component detection unit AC 140 checks whether there is at least one AC component nonzero in the quantized DCT coefficient set that is provided from the Q 135 unit and provides the result verification to a CBPY generation unit. If the verification result represents that the set of quantized DCT coefficients contains at least one non-zero AC component, the CBPY generation unit 150 generates a CBPY bit, for example "1" for the set and otherwise a CBPY bit, for example "0". If the CBPY bits for all sets of DCT coefficients, ie all non-transparent DCT blocks corresponding to the macro processing block are decided through the above processes, the CBPY generation unit 150 provides the CBPY bits as CBPY information to a CBPY 160 encoding unit. With reference to FIGS. 4A to 4C again, the CBPY information corresponding to the macro block of progressive type Pl has four bits CBPY; and those corresponding to blocks P2 and P3 have two CBPY bits, respectively. The CBPY encoding unit 160 finds a VLC code corresponding to the CBPY information between the VLC tables stored in a VLC table unit 170, wherein the VLC table unit 170 includes several predetermined VLC tables depending on the bit numbers of the information CBPY and a frame type such as a frame I and a frame P and provides the detected VLC code to the MUX 190 as encoded CBPY information. The MUX 190 aggregates the DCT_type information, the encoded texture information, the encoded CBPY information, and the encoded information that is fed to it and provides data stream for the macro processing block in a sequence described in FIG.

Figure 5 to a transmitter (not shown) for transmission. As previously illustrated, according to the first embodiment of the present invention, if the macro processing block is the macro border block, the DCT_type of the macro border block is set to the type of progressive coding. Therefore, the DCT_type information representing the DCT_type does not need to be transmitted to the decoding part since the decoding part already knows the previous rule defined according to the first mode. On the other hand, if the macro processing block is the macro object block, its DCT__type is determined based on the texture information and therefore, the DCT_type information representing the DCT__type should be transmitted to the decoding part. If the encoded information is transmitted to the decoding part in the sequence described in Figure 5, a video signal decoder first decodes the information in a coded manner so as to generate the information in reconstructed form. If the reconstructed form information corresponds to the macro border block, the decoder can predict the number of bits of the CBPY information, ie the number of non-transparent DCT blocks in the macro border block, based on the information of reconstructed form, and that the decoder knows that the macro border block is always encoded according to the progressive coding technique. On the other hand, if the reconstructed shape information corresponds to the macro object block, the decoder can also predict the number of bits of the CBPY information since the macro object block always has four non-transparent DCT blocks. Consequently, although the DCT_type information follows the CBPY information as can be seen from the data stream having the sequence shown in Figure 5, the decoder can reconstruct the CBPY information without errors. With reference to Figure 2, a block diagram of a video signal encoder 20 according to a second embodiment of the present invention is provided. As described through the first embodiment of the present invention, the texture information in a macro processing block is fed to a DCT_type 120 determination unit and a modified DCT unit 230 in parallel and its information correspondingly is coupled to a shape encoder 210. The shape encoder 210 encodes the shape information by using a coding method in known manner, for example the CAE technique described in MPEG-4 to thereby generate information in a coded form to a multiplexer (MUX ) 290 on a line L45. Shape encoder 210 also provides reconstructed form information in the processing macro block that occurs when decoding the information in coded form to a bit number prediction unit CBPY 200 and the modified DCT unit 230 via an L40 line in parallel . The unit for CBPY bit number prediction 200 first reforms the information of reconstructed form in the macro processing block into a progressive block macro and an interlaced type macro block according to the progressive and interlaced coding techniques as exemplarily shown in Figures 4A to 4C, wherein the macro block progressive type is identical to macro processing block. Then, the bit number prediction unit CBPY 200 calculates the numbers of non-transparent DCT blocks in the progressive and interlaced type macro blocks. For example, Figure 4A the numbers of non-transparent DCT blocks in the macroblocks and interlaced type Pl and II, are identical to each other, for example 4. In Figure 4B, the number of non-transparent DCT blocks in the macroblock of progressive type P2 is 2 while serving the non-transparent DCT blocks in the macro block d interlaced type 12 is 4. In Figure 4C, the number of non-transparent DCT blocks in the progressive type macro block T3 is 2 while that of the non-transparent DCT blocks in the interlaced type macro block 13 is 1. The non-transparent DCT block numbers in the progressive type and interlaced type macro blocks are provided in the DCT__type determination unit via lines L50 and L52, respectively. The determination unit DCT_type decides a DCT_type of the macro processing block in response to the texture information in the processing block macro and the non-transparent DCT block numbers have the coupled and interleaved type macro blocks of the CBPY bit number prediction unit 200 for lines L50 and L52. That is, the determination unit DCT_type 220 compares the numbers of non-transparent DCT blocks in the progressive and interlaced macro blocks. That is, the DCT_type 220 determination unit compares the numbers of non-transparent DCT blocks in the progressive type and interlaced equipment macro blocks. As a result of the comparison process, if the numbers of non-transparent DCT blocks in the progressive type and interlaced type macro blocks are different from each other, the determination unit DCT_type 220 decides a type of coding corresponding to a number smaller than the DCT_type of the macro processing block and provides the DCT__type information representing the DCT_type determined only to the modified DCT unit 230 by an L56 line. According to the above rule, the type of progressive coding is chosen as DCT_type in Figure 4B while the type of interleaved coding is chosen in Figure 4C. On the other hand, if the numbers of non-transparent DCT blocks in the progressive type and interlaced type macro blocks are non-zero and identical to each other as illustrated in Figure 4A, the DCT_type determination unit decides the DCT_type of the macro block processing by using a known DCT_type determination method based on the texture information and then outputting the DCT_type information representing the DCT_type of the processing macro macro to the MUX 290 via a line L54 and the modified DCT unit 230, using line L56. Therefore, the texture information in the macro block in Figure 4A can be encoded by using either the progressive or interlaced coding technique according to the DCT_type determined as before. If the numbers of non-transparent DCT blocks in the progressive type and interlaced type macro blocks are zero, ie if the processing macro block is described as the background macro block, the DCT_type 220 determination unit supplies a DCT deactivation signal to the modified DCT unit 230 on line L56. In response to the deactivated or powered off signal, the modified DCT unit 30 stops to perform the DCT process for the macro background block. On the other hand, the conventional coding method, if the macro processing block is determined as the background macro block, the video signal encoder 20 does not perform any processing for the background macro block since its corresponding texture information does not it is coupled to the video signal encoder 20. If the information of type DCT_type in the macro processing block is transferred to it, the modified DCT unit 230 supplies one or more sets of DCT coefficients for the macro processing block in a block base DCT through the use of a conventional DCT method based on texture and reconstructed shape information for the macro processing block with respect to the modified DCT unit 130 in Figure 1. The sets of DCT coefficients produced from the modified DCT unit 230 are sequentially provided to a quantization unit (Q) 235. Since the operations of the other units of the encoder are to video 20, which includes a statistical coding unit 280, a component detection unit AC 240, a generating unit CBPY 250 and a coding unit CBPY 260 are identical to those of the first embodiment of the present invention, Processes performed in the previous units will be omitted for simplicity of explanation below. As illustrated above, according to the second embodiment of the present invention, if the macro processing block is a macro border block, the DCT_type of the macro border is determined by comparing the numbers of the non-transparent DCT blocks in the corresponding progressive and interlacing macro blocks. to the border block macro. That is, a type of coding corresponding to a smaller number is determined as the DCT_type of the macro processing block. Therefore, the DCT__type information representing the DCT_type does not need to be transmitted to a decoding part, since the decoding part already knows the previous rule defined according to the second mode. On the other hand, if the macro processing block is the macro object block, its DCT_type is determined based on the texture information as well as the first mode and subsequently the information DCT__type representing the DCT_type should be transmitted to the decoding part. If the encoded information is transmitted to the decoding part in the sequence in Figure 5, a video signal decoder first decodes the information in a coded manner so as to generate the information in reconstructed form. If the reconstructed shape information corresponds to the macro border block, the decoder can predict the number of bits of the CBPY information, ie the number of non-transparent DCT blocks in the macro border block since the decoder knows the rule used to determine the DCT_type of the macro border block based on the reconstructed form information. If the reconstructed form information corresponds to the macro object block, the decoder can also predict the number of bits of the CBPY information since the macro object block always has four non-transparent DCT blocks. Accordingly, although the DCT_type information follows the CBPY information as illustrated in Figure 5, the decoder can accurately reconstruct the CBPY information. In the first and second embodiments of the present invention, it should be apparent to those of ordinary skill in the art that the form information to be encoded can be used in place of the reconstructed form information. While the present invention has been described with respect to certain preferred embodiments only, other modifications and variations may be made without departing from the spirit and scope of the present invention as set forth in the following claims.

Claims (18)

1. - A method to use in a video signal encoder, to encode texture information of a video signal that includes the texture information and shape information of each of the macro blocks, each macro block has MxM pixels and is divisible in the number P of DCT blocks of equal size, M and P are positive integers, respectively, characterized in that it comprises the steps of: (a) determining a DCT__type of a macro block object based on shape information and texture information in the macro object block, where the DCT_type represents the most effective coding technique between one of progressive encoding techniques and interlaced decoding, to encode the texture information; and (b) generating texture information encoded by adaptive coding of the texture information through the use of the progressive coding technique or the interleaving in response to the DCT_type.

2. - The method according to claim 1, characterized in that step (a) includes the steps of: (all) determining a block type of the target macro block based on the shape information, wherein the block type is determined either as an object or a macro border block, the macro border block includes at least one background pixel located outside of an object expressed by the video signal and at least one object pixel located within the object and the macro block object contains only object pixels; (al2) select the type of progressive encoding as the DCT_type of the macro block object if the macro block object is the macro block border; and (A13) decide the DCT_type of the macro object block when using the texture information if the macro object block is determined as the macro block object and provide DCT_type information representing the decided DCT_type.

3. - The method according to claim 1, characterized in that step (a) includes the steps of: (a21) reconstitute the form information in the macro target block in a progressive block macro and one interleaved type according to the techniques of progressive and interlaced coding, respectively; (a22) calculating the non-transparent DCT block numbers in the progressive type and interlaced type macro blocks, wherein each non-transparent DCT block has a DCT block size and contains at least one object pixel located within an object expressed by the video signal; and (a23) deciding the DCT_type of the macro object block based on the texture information and the numbers of the non-transparent DCT blocks in the progressive type and interlaced type macro blocks.

4. - The method according to claim 3, characterized in that step (a23) contains the steps of: (a231) comparing the numbers of the non-transparent DCT blocks in the progressive type and interlaced type macro blocks; (a232) selecting an encoding type corresponding to a smaller number such as the DCT_type of the target macro block if the non-transparent DCT block numbers in the progressive type and interlaced type macro blocks are different feach other; and (a233) deciding the DCT_type of the target macro block when using the texture information if the numbers of the non-transparent DCT blocks in the progressive and interlaced macro blocks are non-zero identical to each other and provide DCT_type information representing the determined DCT_type .

5. - The method according to claim 2 or 3, characterized in that step (b) that includes the steps of: (bl) reconstitute the texture information and shape information in response to the DCT_type; (b2) detecting one or more non-transparent DCT blocks for the target macro block based on the information in reconstituted form; (b3) converting the reconstituted texture information corresponding to each of the non-transparent DCT blocks into a set of DCT coefficients; (b4) quantify the set of DCT coefficients in order to produce a set of quantized DCT coefficients; and (b5) producing the coded texture information by encoding the sets of quantized DCT coefficients that correspond to all non-transparent DCT blocks.

6. The method according to claim 5, characterized in that it further comprises the steps of: (cl) verifying if there is at least one non-zero AC component in the set of quantized DCT coefficients corresponding to each of the non-zero DCT blocks. transparent; (d) producing the CBPY information that represents whether each of the quantized DCT coefficient sets corresponds to the macro block object contains at least one non-zero AC component there in accordance with the results of step (cl); and (the) provide encrypted CBPY information when coding the CBPY information.

7. - The method according to claim 6, characterized in that it further comprises the step of producing information in a coded form when encoding the shape information in the target macro block.

8. - The method according to claim 7, characterized in that it further comprises the step of supplying a data stream to be transmitted containing information in sequence of the information in encoded form, the encoded CBPY information, the DCT_type information and the information of encoded texture.

9. - The method according to claim 6, characterized in that it also comprises, before stage (a), the step of producing information in a coded form when coding data in the form of power in the objective macro block and generating the information in a the target macro block by decoding the information in a coded form.

10. - The method according to claim 9, characterized in that it further comprises the step of supplying a data stream to be transmitted containing encoded information in sequence of the encoded information, the encoded CBPY information, the DCT_type information and the information of coded texture.

11. - An apparatus for encoding a video signal that includes information of texture and shape information in each of the macro blocks, a macro block has MxM pixels and that is divisible in the number P of DCT blocks of equal size, M and P are positive integers respectively, characterized in that it comprises: means for producing information in encoded form by coding the shape information in a target macro block and generating information in reconstructed form by decoding the information in encoded form; means for determining a DCT_type of the target macro block based on the reconstructed shape information and the texture information in the target macro block and providing the DCT_type information representing the DCT_type, where the DCT_type represents the most effective coding technique among techniques of progressive and interlaced coding to encode the texture information; and means for generating coded texture information by adaptively encoding the texture information through the use of the progressive coding or interlaced coding technique in response to the DCT information.

12. - The apparatus according to claim 11, characterized in that the means for DCT_type determination include: means for determining a block type of the target macro block based on the reconstructed form information, wherein the type of block is determined already either as an object or a macro border block, the macro border block includes at least one background pixel located outside of an object expressed by the video signal and at least one object pixel located inside the object, and the macro block object contains only object pixels and provide a block indication signal representing the type of block; and means for deciding the DCT_type of the macro object block in response to the block indication signal and providing the DCT_type information.

13. - The apparatus according to claim 12, characterized in that if the block indication signal represents the macro border block, the DCT_type of the target macro block becomes a type of progressive coding and if the block indication signal shows the macro object block, the DCT_type decision means determine the DCT__type of the macro object block when using the texture information.

14. - The apparatus according to claim 11, characterized in that the means for determining DCT_type include: means for reconstituting the reconstructed form information into one of progressive type and interlaced macro blocks according to the progressive coding techniques and interlaced, respectively; means for calculating the non-transparent DCT block numbers in the progressive type and interlaced type macro blocks, wherein each non-transparent DCT block has a similar block size and contains at least one object pixel located within an object expressed by the video signal; and means for deciding the DCT_type of the macro object block based on texture information and non-transparent DCT block numbers in the progressive type and interlaced type macro blocks.

15. - The apparatus according to claim 14, characterized in that the means for determining DCT_type contain: means for comparing the numbers of non-transparent DCT blocks in the progressive-type and interlaced-type macro blocks; means for selecting a type of coding corresponding to a number smaller than the DCT__type of the target macro block, if the numbers of non-transparent DCT blocks in the progressive type and interlaced type macro blocks are different from each other; and means for deciding the DCT_type of the target macro block when using the texture information if the numbers of the non-transparent DCT blocks in the macro blocks of progressive type and interleaved type are non-zero identical to each other and provide DCT type information representing the DCT_type decided.

16. The apparatus according to claim 12 or 14, characterized in that the encoded texture information generating means includes: means for reconstituting texture information and reconstructed form information in response to the DCT_type; means for detecting one or more non-transparent DCT blocks for the target macro block, based on the information in reconstituted form; means for converting the reconstituted texture information corresponding to each of the non-transparent DCT blocks into a set of DCT coefficients; means for quantifying the set of DCT coefficients in order to produce a set of quantized DCT coefficients; and means for producing the coded texture information by encoding sets of quantized DCT coefficients that correspond to all non-transparent DCT blocks.

17. The apparatus according to claim 16, further comprising means for verifying if there is at least one non-zero AC component in the set of quantized DCT coefficients corresponding to each of the non-transparent DCT blocks; means for producing CBPY information representing whether each of the sets of quantized DCT coefficients corresponding to the macro target block contains at least one non-zero AC component in accordance with the verification result; and means for providing encoded CBPY information when encoding the CBPY information.

18. The apparatus according to claim 17, further comprising: means for supplying a data stream to be transmitted containing encoded information in sequence of the encoded information, the encoded CBPY information, the DCT_type information and the information of coded texture. SUMMARY OF THE INVENTION A video signal encoder encodes a video signal including texture information and shape information in each of the macro blocks, a macro block has 16 x 16 pixels and is divisible into four equal DCT block numbers size. The encoder produces information in a coded form by encoding the form information in a macro processing block and generates information in a reconstructed form by decoding the information in a coded form. Then, a DCT_type of the macro processing block is determined based on the reconstructed shape information and the texture information in the macro processing block to thereby provide DCT_type information representing the DCT_type. Once the DCT_type of the macro processing block is decided, the encoder generates the coded texture information by adaptively encoding the texture information through the use of a progressive or interlaced coding technique in response to the DCT_type information. In addition, the encoder generates CBPY information by using the encoding results of the texture information and provides a stream of data to be transmitted in sequence of the encoded information, the encoded CBPY information, the DCT_type information and the encoded texture information .