WO2012090504A1

WO2012090504A1 - Methods and apparatuses for coding and decoding video stream

Info

Publication number: WO2012090504A1
Application number: PCT/JP2011/007352
Authority: WO
Inventors: Xuan Jing; Chong Soon Lim; Viktor Wahadaniah; Sue Mon Thet Naing; Hisao Sasai; Takahiro Nishi; Youji Shibahara; Toshiyasu Sugio
Original assignee: Panasonic Corporation
Priority date: 2010-12-28
Filing date: 2011-12-28
Publication date: 2012-07-05

Abstract

A video decoding method is provided for decoding a coded video stream and a video encoding method is provided for encoding a video stream into a coded video stream. The coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit. The methods include judging whether a type of the prediction unit is a predefined type. If said prediction unit type is the predefined type, a transform size for a chroma residual data of the coded unit is set to be equal to a prediction unit size for the chroma residual data of the coded unit. On the other hand, if said prediction type is not the predefined type, a transform size for a chroma residual data of the coded unit is set so as to be equal to a factor of a transform size for a luma residual data. There are also provided corresponding video decoding and encoding apparatuses.

Description

METHODS AND APPARATUSES FOR CODING AND DECODING VIDEO STREAM

The present invention relates to a video decoding method, a video encoding method, and apparatuses thereof.

In video coding standards such as MPEG-1, MPEG-2, H.263 and MPEG-4/AVC, a video picture is divided into a number of non-overlapped square shaped blocks i.e., macroblocks. In the upcoming standard e.g., High Efficiency Video Coding (HEVC) standard, a video picture is also divided into a number of largest coding units (LCU). These LCUs have similar role to the macroblocks in the previous video coding standards. Different from fixing the macroblock size of 16 pixels by 16 pixels for luminance samples in previous standards, in HEVC standard, the size of the LCU can be much larger than 16 by 16 pixels e.g., 128 pixels by 128 pixels. By supporting of various LCU sizes greater than the conventional macroblock size, the HEVC standard can achieve better compression efficiency for large homogeneous regions in the video while maintaining the efficiency for coding low resolution videos.

ISO/IEC 14496-10, "MPEG-4 Part 10 Advanced Video Coding"

Similar to macroblocks which can be further divided into sub-macroblocks, the LCU in the new standard also can be split into multiple coding units (CU) with smaller sizes. The splitting process is based on hierarchical tree structure and the size of each CU within the LCU is implicitly represented by a series of CU size parameters. In the compressed domain, the main components of a LCU or a CU include a CU header, a prediction unit and a transform unit. Basically, the CU header contains information about the location and the size of a CU, the prediction unit contains information about how a CU is predicted from the previous reconstructed image samples and the transform unit contains the quantized transform coefficients of the residual image blocks.

For intra prediction, the pixels in the current block are usually predicted from the spatially neighboring reconstructed blocks which are to the left and to the above of the current block. Therefore, during decoding process, the blocks to the above and to the left must be reconstructed independently before decoding the current block. For example, when a CU of size 2Nx2N is intra coded and its prediction unit size is NxN, according to the property of intra prediction, each partition has to be encoded and decoded separately including transform and inverse transform process. Thus the transform unit must also be split into the same partition size of NxN as the prediction unit does. Because the human visual system is less sensitive to the chrominance (chroma) than to the luminance (luma), the chroma components are usually subsampled by a factor of 2 both horizontally and vertically compared to the luma component. As a result, in the previous example, if the luma transform size is NxN, the chroma transform size should be halved in both dimensions which is N/2xN/2. However, using four smaller transforms of N/2xN/2 for a chroma intra residual block of NxN needs to encode four DC coefficients instead of encoding only one DC coefficient when NxN transform is used.

For inter prediction, in some cases, a dimension of the inter prediction unit for chroma samples may be smaller than the smallest supported dimension of the transform unit. Therefore, if the transform unit size is determined or selected so as to be the same as the prediction unit size, a problem would arise since the transform unit size would not be supported.

It is against this background that the present invention has been developed.

In an embodiment of the present invention, to solve or at least mitigate the above-described problems, an adaptive method for selecting transform size for the chroma residue block in a CU is proposed. Due to the fact that the chroma signals are generally very smooth, for intra coded block, it may be more efficient to code the chroma intra block of NxN using NxN transform to save the bits of DC coefficients. Specifically, an additional condition is introduced to check the type of the prediction unit, such as whether the prediction unit is intra coded or not. For example, if the type of the prediction unit is detected or determined to be intra coded, the chroma transform size will be selected or set to be equal to its prediction unit size, otherwise the chroma transform size will be selected or set based on the luma transform size, such as to be equal to a factor of the luma transform size. For example, if the type of the prediction unit is detected or determined to be inter coded (which is not intra coded) and if a dimension of the inter prediction unit is smaller than the smallest supported dimension (e.g., 4 x 4) of the transform unit, the transform unit for the chroma samples is set to be a factor (e.g., one fourth) of the luma transform size in one dimension. In this regard, by way of example, if the luma transform size is 16 by 4, the chroma transform size is set to be 4 by 4 for example. As a result, the chroma transform unit may not always be split when luma transform unit is split into four smaller units and better compression efficiency can be achieved. In addition, it can be ensured that the transform unit size determined is supported.

An advantage associated with an embodiment of the present invention is the improved efficiency in coding chroma residual data for a CU, which for example can provide better rate distortion performance for the video encoder. Different from the traditional methods which normally choose a predefined transform matrix for chroma component regardless of the macroblock prediction type and partition size, in embodiment(s) of the present invention, the transform matrix used for chroma residue can be selected adaptively according to the prediction unit type (such as whether the prediction unit type is intra-coded or inter-coded) and prediction unit size (such as whether the prediction unit is smaller than the smallest supported dimension of the transform unit).

The effects of embodiments of the present invention are better compression efficiency because the bits in coding DC coefficients for chroma intra residual data are reduced, providing an adaptive selection of transform matrix size that has more flexibility for chroma component, and/or avoiding setting an unsupported transform unit size.

According to a first aspect of the present invention, there is provided a video decoding method for decoding a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the method comprising:
judging whether a type of the prediction unit is a predefined type;
wherein, if said prediction unit type is the predefined type,
setting a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit;
wherein, if said prediction type is not the predefined type,
setting a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data;
selecting a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.

According to a second aspect of the present invention, there is provided a video encoding method for encoding a video stream into a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the method comprising:
judging whether a type of the prediction unit is the predefined type;
wherein, if said prediction unit type is the predefined type,
setting a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit;

wherein, if said prediction unit type is not the predefined type,
setting a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data;
selecting a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.

According to a third aspect of the present invention, there is provided a video decoding apparatus for decoding a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the apparatus comprising:
a judging unit operable to judge whether a type of the prediction unit is the predefined type;
a setting unit operable to set a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit if said prediction unit type is the predefined type, and operable to set a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data if said prediction unit type is not the predefined type; and
a selecting unit operable to select a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.

According to a fourth aspect of the present invention, there is provided a video encoding apparatus for encoding a video stream into a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the apparatus comprising:

a judging unit operable to judge whether a type of the prediction unit is the predefined type;
a setting unit operable to set a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit if said prediction unit type is the predefined type, and operable to set a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data if said prediction unit type is not the predefined type; and
a selecting unit operable to select a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which
Figure 1 is a diagram illustrating examples of the largest coding unit (LCU) structure and examples of locations of the coding unit size parameter, prediction unit type parameter, prediction unit size parameter and transform size parameter in a coded picture of the present invention. Figure 2 is a block diagram illustrating an example apparatus for a video encoder using present invention. Figure 3 is a block diagram illustrating an example apparatus for a video decoder using present invention. Figure 4 is a flowchart showing the video decoding process in the first embodiment of present invention. Figure 5 is a flowchart showing the video encoding process in the first embodiment of present invention. Figure 6 is a flowchart showing the prediction unit size determination process in the first embodiment of present invention. Figure 7 is a flowchart showing the luma transform size determination process in the first embodiment of present invention. Figure 8 illustrates examples of setting the size of the transform unit for the chroma residual data according to an aspect of the present invention. Figure 9 is an overall configuration of a content providing system for implementing content distribution services. Figure 10 is an overall configuration of a digital broadcasting system. Figure 11 is a block diagram illustrating an example of a configuration of a television. Figure 12 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. Figure 13 is a drawing showing an example of a configuration of a recording medium that is an optical disk. Figure 14A is a drawing illustrating an example of a cellular phone. Figure 14B is a block diagram showing an example of a configuration of the cellular phone. Figure 15 is a drawing showing a structure of multiplexed data. Figure 16 is a drawing schematically illustrating how each of the streams is multiplexed in multiplexed data. Figure 17 is a drawing illustrating how a video stream is stored in a stream of PES packets in more detail. Figure 18 is a drawing showing a structure of TS packets and source packets in the multiplexed data. Figure 19 is a drawing showing a data structure of a PMT. Figure 20 is a drawing showing an internal structure of multiplexed data information. Figure 21 is a drawing showing an internal structure of stream attribute information. Figure 22 is drawing showing steps for identifying video data. Figure 23 is a 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. Figure 24 is a drawing showing a configuration for switching between driving frequencies. Figure 25 is a drawing showing steps for identifying video data and switching between driving frequencies. Figure 26 is a drawing showing an example of a look-up table in which the standards of video data are associated with the driving frequencies. Figure 27A is a drawing showing an example of a configuration for sharing a module of a signal processing unit. Figure 27B is a drawing showing another example of a configuration for sharing a module of a signal processing unit.

(Embodiment1)
Embodiment 1 of the present invention relates to methods and apparatuses for coding and decoding any multimedia data, more particularly, image and/or video data. For example, according to an aspect, there is provided a chroma transform size selection process for use in video encoding and decoding schemes.

Figure 1 shows a diagram illustrating an example coding structure of a coded picture in the compressed domain and examples of the locations of coding unit size parameter, prediction unit type parameter, prediction unit size parameter and transform size parameter. As can be seen in Figure 1, one picture (D100) consists of a picture header (D102) and a number of LCUs (D104 and D106). Every LCU can be further split into a series of CUs (D112 and D126) with smaller sizes or the LCU e.g., (D106) has not been further split. The information of whether or not the LCU and the CU will be split is signaled by CU size parameters (D108, D116, D128 and D136) which are located in CU headers (D110, D114 and D134). Besides a header, each LCU or CU has a prediction unit (D122 and D142) and a transform unit (D124 and D146). For prediction unit, according to the prediction type e.g., intra (spatial prediction) or inter (temporal prediction), it can be divided into different sub-partitions. Similar to the LCU splitting the transform unit also has the ability to be further split into a series of sub transform units (D132 and D148). The size of a transform unit or sub transform unit is the dimension corresponding to the transform matrix used to transform the residual data of a CU. Note that, the transform size information is signaled by transform size parameters (D130, D144 and D150) and each transform unit which will not be split contains the quantized transform coefficients corresponding to a specific transform.

The prediction unit comprises information about how a CU is predicted from the previous reconstructed image samples. The prediction unit may comprise one block of prediction samples or a block unit of prediction samples (i.e., comprising a plurality of blocks of prediction samples). For example, a 8x8 intra prediction unit may have 4 blocks of 4x4 prediction samples but they share the same intra prediction direction. But it is impossible to create a block of 8x8 prediction samples without reconstructing a smaller block of 4x4 prediction samples within the 8x8 block.

Figure 2 shows a block diagram illustrating an example apparatus for a video encoder according to Embodiment 1 of the present invention. The apparatus comprises a subtraction unit 200, a transform unit 202, a quantization unit 204, an entropy coding unit 206, an inverse quantization unit 208, an inverse transform unit 210, an adding unit 212, a transform selection unit 214, a mode selection unit 216, an intra prediction unit 218, a filtering unit 220, a memory unit 222, a motion estimation unit 224, and a motion compensation unit 226.

As shown in Figure 2, the subtraction unit 200 takes original samples D200 of the uncompressed image and subtracts with predicted image samples D228 to output the residual data D202. The transform unit 202 uses the selected transform matrix D230 from transform selection unit 214 to transform the residual data D202 to the transformed coefficients D204. The transformed coefficients D204 are then quantized by the quantization unit 204 to output the quantized transform coefficients D206. The quantized transform coefficients D206 are further entropy encoded into the compressed video D208 by an entropy coding unit 206. The inverse quantization unit 208 performs inverse quantization on the quantized transform coefficients D206 and outputs the reconstructed transform coefficients D210. Then the reconstructed transform coefficients D210 are inverse transformed to pixel domain reconstructed residual data D212 by the inverse transform unit 210. The adding unit 212 takes the reconstructed residual data D212 and adds with the predicted image samples D228 to reconstruct the image samples D214. The filtering unit 220 takes the reconstructed image samples D214 and outputs filtered image samples D216 which are then stored in the memory unit 222. The motion estimation unit 224 finds the temporal prediction of the original image samples D200 from the previously reconstructed image samples D218 and outputs motion information D220. The motion compensation unit 226 takes the motion information D220 and the previously reconstructed image samples D218 to construct the motion compensated image samples D222. The intra prediction unit 218 performs spatial prediction for the original image samples D200 based on the reconstructed image samples D214 to output the intra predicted image samples D224. The mode selection unit 216 selects the best prediction from the motion compensated image samples D222 and the intra predicted image samples D224 and outputs the predicted image samples D228 as well as the prediction mode information D226. The transform selection unit 214 takes the prediction mode information D226 and outputs the selected transform matrix D230.

Figure 3 shows a block diagram illustrating an example apparatus for a video decoder according to Embodiment 1 of the present invention. The video decoder comprises an entropy decoding unit 300, an inverse quantization unit 302, an inverse transform unit 304, an adding unit 306, a filtering unit 308, a transform selection unit 310, a mode selection unit 312, a motion compensation unit 314, an intra prediction unit 316, and a memory unit 318.

As shown in Figure 3, the entropy decoding unit 300 reads a compressed video D300 and outputs the compressed residual data D302. The entropy decoding unit 300 also decodes the prediction mode information D316, the motion information D314 and intra prediction information D312. The inverse quantization unit 302 performs inverse quantization for the input compressed residual data D302 and outputs the decoded transform coefficients D304. The inverse transform unit 304 takes the selected transform matrix D318 and performs inverse transform for the decoded transform coefficients D304 to generate the decoded residual data D306. The adding unit 306 adds decoded residual data D306 with predicted images samples D324 to output the reconstructed image samples D308. The filtering unit 308 reads the reconstructed image samples D308 and outputs filtered image samples D310. The filtered image samples D310 are also stored in the memory unit 318. The motion compensation unit 314 takes the motion information D314 and the previously reconstructed image samples D326 to construct the motion compensated image samples D320. The intra prediction unit 316 reads the intra prediction information D312 and reconstructed image samples D308 to construct the intra predicted image samples D322. The mode selection unit 312 selects for the output predicted image samples D324 from the input motion compensated image samples D320 and intra predicted image samples D322. The transform selection unit 310 takes the decoded prediction mode information D316 and outputs the selected transform matrix D318.

Figure 4 shows a flowchart describing an exemplary video decoding process according to Embodiment 1 of the present invention. Firstly in module 400, a first set of parameters are parsed from a coded coding unit of the compressed video stream and then the chroma prediction unit size which is the dimension of the two dimensional block of predicted chroma image samples is determined according to the parsed parameters. For example, the parsed parameters comprise coding unit size parameters and the prediction unit size parameter. Figure 6 shows a detailed flowchart for the process in module 400. Next in module 402, a prediction unit type parameter is parsed from the coded coding unit and the prediction unit type (e.g., intra or non-intra) is determined based on the parsed prediction unit type parameter. Module 404 parses a second set of parameters from a coded coding unit and the transform size for luma residual data of this coding unit is determined according to said parsed parameters. More detailed description of this process is illustrated in Figure 7. Module 406 then determines or judges whether or not the prediction unit type is the same as predefined type (e.g., the predefined type can be intra). When the prediction unit type is the predefined type (e.g., intra), module 408 sets transform size for chroma residual data equal to the chroma prediction unit size. Otherwise, for example if the prediction unit type is inter, module 410 sets transform size for chroma residual data equal to a factor of the transform size for luma residual data. For example, the factor can be one fourth (e.g., both vertical and horizontal dimensions are halved or either vertical or horizontal dimension is reduced by a factor of one fourth) when the video is in YUV 4:2:0 format. By way of example, if the type of the prediction unit is detected or judged to be inter coded (which is not intra) and if a dimension of the inter prediction unit is smaller than the smallest supported dimension (e.g., 4x4) of the transform unit, the size of transform unit for the chroma residual data is set to be a factor (e.g., one fourth) of the luma transform size in one dimension. In this regard, for instance, if the luma transform size is 16 by 4, the chroma transform size is set to be 4 by 4 (i.e., the vertical dimension is reduced by a factor of one fourth). This example is graphically illustrated in Figure 8. Next in module 412, a transform matrix for chroma residual data is selected from plurality of predefined transform matrixes based on the set transform size for the chroma residual block. Module 414 finally decodes a block of chroma image samples from the compressed video which involves the inverse transform process using said selected chroma transform matrix and prediction based on said prediction unit type.

Figure 5 shows a flowchart describing an exemplary video encoding process according to Embodiment 1 of the present invention. Firstly in module 500, a first set of parameters are written or embedded into a coded coding unit of the compressed video stream. The chroma prediction unit size which is the dimension of the two dimensional block of predicted chroma image samples can be determined or indicated according to the written parameters. The first set of parameters comprises e.g., coding unit size parameters and the prediction unit size parameter. Next in module 502, a prediction unit type parameter is written or embedded into the coded coding unit. The prediction unit type (e.g., intra or non-intra) can be determined or indicated based on the prediction unit type parameter. Module 504 writes a second set of parameters into the coded coding unit and the transform size for luma residual data of this coding unit can be determined or indicated according to the written parameters. Module 506 detects or judges whether or not the prediction unit type is the same as predefined type (e.g., the predefined type can be intra). When the prediction unit type is the predefined type (e.g., intra), module 508 sets transform size for chroma residual data equal to the chroma prediction unit size. Otherwise, for example if the prediction unit type is inter, module 510 sets transform size for chroma residual data equal to a factor of the transform size for luma residual data determined in module 504. As mentioned before, for example, the factor can be one fourth (e.g., both vertical and horizontal dimensions are halved or either vertical or horizontal dimension is reduced by a factor of one fourth) when the video is in YUV 4:2:0 format. By way of example, if the type of the prediction unit is detected or judged to be inter coded (which is not intra) and if a dimension of the inter prediction unit is smaller than the smallest supported dimension (e.g., 4x4) of the transform unit, the size of transform unit for the chroma residual data is set to be a factor (e.g., one fourth) of the luma transform size in one dimension. In this regard, for instance, if the luma transform size is 16 by 4, the chroma transform size is set to be 4 by 4 (i.e., the vertical dimension is reduced by a factor of one fourth). This example is graphically illustrated in Figure 8. Next in module 512, a transform matrix for chroma residual data is selected from plurality of predefined transform matrixes based on the set transform size for the chroma residual block. Finally, module 514 encodes a block of chroma image samples which involves the transform using said selected chroma transform matrix and prediction based on said prediction unit type.

Although a factor of one fourth has been described hereinabove, it will be apparent to the person skilled in the art that other factors can be applied depending on the video format. For example, the factor may be one when the video is in YUV 4:4:4 format. As another example, the factor may be one half when the video is in YUV 4:2:2 format.

Figure 6 shows a flowchart illustrating the prediction unit size determination process in Embodiment 1 of present invention. Firstly module 600 parses coding unit size parameters from a coded largest coding unit. Examples of the locations of said coding unit size parameters are shown in Figure 1. Module 602 then determines the spatial size/dimension of a coding unit based on said parsed coding unit size parameters. Next in module 604, a prediction unit size parameter is parsed from a coded coding unit. Examples of the locations of said prediction unit size parameter is shown in Figure 1. Finally, module 606 determines the spatial domain chroma prediction unit size based on the coding unit size and said parsed prediction unit size parameter.

Figure 7 shows a flowchart illustrating the luma transform size determination process in Embodiment 1 of present invention. Firstly module 700 parses transform size parameters from a coded coding unit. Examples of the locations of said transform size parameters are shown in Figure 1. Next, module 702 selects the transform size for luma residual data based on the coding unit size determined from module 602 in Figure 6 and said parsed transform size parameters.

(Embodiment 2)
The processing described in each of Embodiments can be simply implemented in an independent computer system, by recording, in a recording medium, a program for implementing the configurations of the video coding method and the video decoding method described in each of Embodiments. The recording media may be any recording media as long as the program can be recorded, such as a magnetic disk, an optical disk, a magnetic optical disk, an IC card, and a semiconductor memory.

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.

FIG. 9 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 ex110 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 ex113, 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 ex110, respectively.

However, the configuration of the content providing system ex100 is not limited to the configuration shown in FIG. 9, 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 ex113, such as a digital video camera, is capable of capturing video. A camera ex116, such as a digital video camera, is capable of capturing both still images and video. Furthermore, the cellular phone ex114 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 ex113 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 ex111, the PDA ex112, the camera ex113, the cellular phone ex114, 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 ex113 or the streaming server ex103 that transmits the data, or the coding processes may be shared between the camera ex113 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 ex111. The coding processes may be performed by the camera ex116, the computer ex111, 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 ex111 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 ex111 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 FIG. 10. 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.

FIG. 11 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, FIG. 12 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.

FIG. 13 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 ex211 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 FIG. 11. The same will be true for the configuration of the computer ex111, the cellular phone ex114, and others.

FIG. 14A illustrates the cellular phone ex114 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 ex110; 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 FIG. 14 B. In the cellular phone ex114, 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 ex114.

In the cellular phone ex114, 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 ex114, 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 ex110 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 ex114 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.

(Embodiment 3)
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, MPEG4-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.

FIG. 15 illustrates a structure of the multiplexed data. As illustrated in FIG. 15, 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, MPEG4-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, 0x1011 is allocated to the video stream to be used for video of a movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to 0x121F are allocated to the presentation graphics streams, 0x1400 to 0x141F are allocated to the interactive graphics streams, 0x1B00 to 0x1B1F are allocated to the video streams to be used for secondary video of the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams to be used for the secondary video to be mixed with the primary audio.

FIG. 16 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.

FIG. 17 illustrates how a video stream is stored in a stream of PES packets in more detail. The first bar in FIG. 17 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 FIG. 17, 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.

FIG. 18 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 FIG. 18. 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.

FIG. 19 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 FIG. 20. 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 FIG. 20, 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 FIG. 21, 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.

In Embodiment 3, 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, FIG. 22 illustrates steps of the video decoding method according to Embodiment 3. 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, MPEG4-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 in Embodiment 3 can be used in the devices and systems described above.

(Embodiment 4)
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, FIG. 23 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 ex117, 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 ex511, 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 ex511 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.

(Embodiment 5)
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, MPEG4-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. FIG. 24 illustrates a configuration ex800 in Embodiment 5. 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 FIG. 23. 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 FIG. 21. 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 in Embodiment 3 is probably used for identifying the video data. The identification information is not limited to the one described in Embodiment 3 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 FIG. 26. 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.

FIG. 25 illustrates steps for executing a method in Embodiment 5. 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, MPEG4-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 MPEG4-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, MPEG4-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, MPEG4-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, MPEG4-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.

(Embodiment 6)
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, MPEG4-AVC, and VC-1 are partly shared. Ex900 in FIG. 27A 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 MPEG4-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 probably includes use of a decoding processing unit ex902 that conforms to MPEG4-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 a transformation unit in particular, for example, the dedicated decoding processing unit ex901 is used for inverse transform. Otherwise, the decoding processing unit is probably shared for one of the entropy coding, inverse quantization, deblocking filtering, and 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 MPEG4-AVC.

Furthermore, ex1000 in FIG. 27B 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 of Embodiment 6 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.

It will be appreciated by those skilled in the art that modifications and variations to the invention described herein will be apparent departing from the spirit and scope thereof. The variations and modifications as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

The present invention is applicable to a coding apparatus which codes audio, still images, and video and to a decoding apparatus which decodes data coded by the coding apparatus. For example, the present invention is applicable to various audio-visual devices such as audio devices, cellular phones, digital cameras, BD recorders, and digital televisions.

Claims

A video decoding method for decoding a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the method comprising:

judging whether a type of the prediction unit is a predefined type;

wherein, if said prediction unit type is the predefined type,

setting a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit;

wherein, if said prediction type is not the predefined type,

setting a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data;

selecting a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.
The video decoding method according to claim 1, wherein said setting the transform size for the chroma residual data comprises setting the transform size for the chroma residual data equal to the factor in one dimension only or in two dimensions.
The video decoding method according to claim 2, wherein if said prediction type is not the predefined type, the method further determines whether a dimension of the prediction unit is smaller than a smallest supported dimension of the transform unit, and if the dimension of the prediction unit is smaller than the smallest supported dimension of the transform unit, the transform size for the chroma residual data is set to be equal to the factor in one dimension only.
The video decoding method according to claim 3, wherein the smallest supported dimension of the transform unit is 4 x 4.
The video decoding method according to any one of claims 1 to 4, wherein the factor is one, one half, or one fourth.
The video decoding method according to any one of claims 1 to 5, wherein the predefined type is intra coding.
The video decoding method according to any one of claims 1 to 6, wherein the prediction unit type is intra coding.
The video decoding method according to any one of claims 1 to 6, wherein the prediction unit type is inter coding.
The video decoding method according to any one of claims 1 to 8, wherein the method further comprises parsing a first set of parameters from the coded unit to determine a two dimensional chroma prediction unit size of the coded unit.
The video decoding method according to any one of claims 1 to 9, wherein the method further comprises parsing a parameter from the coded unit to determine the prediction type of the coded unit.
The video decoding method according to any one of claims 1 to 10, wherein the method further comprises parsing a second set of parameters from the coded unit to determine the transform size for the luma residual data of the coded unit.
The video decoding method according to claim 9, wherein said chroma prediction unit size represents the dimensions of the two dimensional block of predicted chroma image samples.
The video decoding method according to claim 11, wherein said transform size represents the dimension of the two dimensional transform matrix used to transform spatial domain residual block data into transform domain coefficient block.
A video encoding method for encoding a video stream into a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the method comprising:

judging whether a type of the prediction unit is the predefined type;

wherein, if said prediction unit type is the predefined type,

setting a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit;

wherein, if said prediction unit type is not the predefined type,

setting a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data;

selecting a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.
The video encoding method according to claim 14, wherein said setting the transform size for the chroma residual data comprises setting the transform size for the chroma residual data equal to the factor in one dimension only or in two dimensions.
The video encoding method according to claim 15, wherein if said prediction type is not the predefined type, the method further determines whether a dimension of the prediction unit is smaller than a smallest supported dimension of the transform unit, and if the dimension of the prediction unit is smaller than the smallest supported dimension of the transform unit, the transform size for the chroma residual data is set to be equal to the factor in one dimension only.
The video encoding method according to claim 16, wherein the smallest supported dimension of the transform unit is 4 x 4.
The video encoding method according to any one of claims 14 to 17, wherein the factor is one, one half, or one fourth.
The video encoding method according to any one of claims 14 to 18, wherein the predefined type is intra coding.
The video encoding method according to any one of claims 14 to 19, wherein the prediction unit type is intra coding.
The video encoding method according to any one of claims 14 to 19, wherein the prediction unit type is inter coding.
The video encoding method according to any one of claims 14 to 21, wherein the method further comprises writing a first set of parameters into the video stream for indicating a two dimensional chroma prediction unit size of the coded unit.
The video encoding method according to any one of claims 14 to 22, wherein the method further comprises writing a parameter into the video stream for indicating the prediction type of the coded unit.
The video encoding method according to any one of claims 14 to 23, wherein the method further comprises writing a second set of parameters into the video stream for indicating the transform size for the luma residual data of the coded unit.
The video encoding method according to claim 22, wherein said chroma prediction unit size represents the dimension of the two dimensional block of predicted chroma image samples.
The video encoding method according to claim 24, wherein said transform size represents the dimension of the two dimensional transform matrix used to transform spatial domain residual block data into transform domain coefficient block.
A video decoding apparatus for decoding a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the apparatus comprising:

a judging unit operable to judge whether a type of the prediction unit is the predefined type;

a setting unit operable to set a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit if said prediction unit type is the predefined type, and operable to set a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data if said prediction unit type is not the predefined type

a selecting unit operable to select a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.
The video decoding apparatus according to claim 27 further comprises a parsing unit operable to parse a first set of parameters from the coded unit to determine a two dimensional chroma prediction unit size of the coded unit.
The video decoding apparatus according to claim 28, wherein the parsing unit is further operable to parse a parameter from the coded unit to determine the prediction type of the coded unit.
The video decoding apparatus according to claim 28 or 29, wherein the parsing unit is further operable to parse a second set of parameters from the coded unit to determine the transform size for the luma residual data of the coded unit.
A video encoding apparatus for encoding a video stream into a coded video stream, the coded video stream including a plurality of coded units, each coded unit including a prediction unit and a transform unit, the apparatus comprising:

a judging unit operable to judge whether a type of the prediction unit is the predefined type;

a setting unit operable to set a transform size for a chroma residual data of said coded unit equal to a prediction unit size for the chroma residual data of said coded unit if said prediction unit type is the predefined type, and operable to set a transform size for a chroma residual data of said coded unit equal to a factor of a transform size for a luma residual data if said prediction unit type is not the predefined type; and

a selecting unit operable to select a transform matrix for said chroma residual data from a plurality of predefined transform matrixes based on said set transform size for the chroma residual data.
The video encoding apparatus according to claim 31, further comprising a writing unit operable to write a first set of parameters into the video stream for indicating a two dimensional chroma prediction unit size of the coded unit.
The video encoding apparatus according to claim 32, wherein the writing unit is further operable to write a parameter into the video stream for indicating the prediction type of the coded unit.
The video encoding apparatus according to claim 33, wherein the writing unit is further operable to write a second set of parameters into the video stream for indicating the transform size for the luma residual data of the coded unit.