Image coding method, image coding apparatus, image decoding method and image decoding apparatus

NOTICE: More than one reissue application has been filed for the reissue of U.S. Pat. No. 8,958,653 B2. Reissue application Ser. No. 15/292,886 is a reissue of U.S. Pat. No. 8,958,653 B2, was filed on Oct. 13, 2016, and issued as U.S. Pat. No. RE48,632 on Jul. 6, 2021. Reissue application Ser. No. 17/336,456 is a reissue of U.S. Pat. No. 8,958,653 B2, is a continuation reissue application of Reissue application Ser. No. 15/292,886, and was filed on Jun. 2, 2021. The present application is a reissue of U.S. Pat. No. 8,958,653 B2, and is a continuation reissue application of Reissue application Ser. No. 17/336,456.

The applicationU.S. patent application Ser. No. 14/157,577, filed Jan. 17, 2014 and now U.S. Pat. No. 8,958,653 issued Feb. 17, 2015,is a continuation ofco-pendingU.S. patent application Ser. No. 13/669,690, filed Nov. 6, 2012, which claims the benefit of U.S. Provisional Patent Application No. 61/556,406 filed on Nov. 7, 2011, the content of which are expressly incorporated herein by reference in their entireties.Reissue application Ser. No. 15/292,886 is a reissue of U.S. Pat. No. 8,958,653 B2, was filed on Oct. 13, 2016, and issued as U.S. Pat. No. RE48,632 on Jul. 6, 2021, Reissue application Ser. No. 17/336,456 is a reissue of U.S. Pat. No. 8,958,653 B2, is a continuation reissue application of Reissue application Ser. No. 15/292,886, and was filed on Jun. 2, 2021. The present application is a Reissue application of U.S. Pat. No. 8,958,653 B2, and is a continuation reissue application of Reissue application Ser. No. 17/336,456. The disclosure of each of the above-identified documents, including the specification, drawings, and claims, is incorporated herein by reference in its entirety.

The present disclosure relates to an image coding technique and an image decoding technique for arithmetic coding or arithmetic decoding.

Applications for providing services via the Internet (e.g., video-conference, digital video broadcast, and Video on Demand services including video content streaming) are increasing. These applications rely on transmission of video data. When the applications transmit video data, most video data is transmitted via a conventional transmission path having a limited bandwidth. Furthermore, when the applications record video data, most video data is recorded on a conventional recording medium having a limited capacity. To transmit video data via the conventional transmission path or record video data on the conventional recording medium, it is indispensable to compress or reduce the data amount of the video data.

In view of this, many video coding standards have been developed to compress video data. These video coding standards are, for example, ITU-T standards denoted as H.26x and ISO/IEC standards denoted as MPEG-x. Currently, the latest and most advanced video coding standard is the standard denoted as H.264/MPEG-4 AVC (see Non Patent Literature 1 and Non Patent Literature 2).

The coding approach underlying most of these video coding standards is based on prediction coding that includes the following main steps of (a) to (d): (a) Divide each video frame into blocks each having pixels to compress data of the video frame on a block-by-block basis. (b) Predict each block based on previously coded video data to identify temporal and spatial redundancy. (c) Subtract the predicted data from the video data to remove the identified redundancy. (d) Compress remaining data (residual blocks) by Fourier transform, quantization, and entropy coding.

As for the step (a), the current video coding standard provides different prediction modes depending on a macroblock to be predicted. According to most of the video coding standards, motion estimation and motion compensation are used for predicting video data based on a previously coded and decoded frame (inter frame prediction). Alternatively, block data may be extrapolated from an adjacent block of the same frame (intra frame prediction).

In the step (d), quantized coefficients included in a current block to be coded are scanned in a predetermined order (scan order). Then, information (SignificantFlag) indicating whether the scanned coefficients are zero coefficients or non-zero coefficients (e.g., binary information (symbol) indicating a non-zero coefficient as 1 and a zero coefficient as 0) is coded.

Furthermore, information (last position information) indicating the position of the last non-zero coefficient in the scan order is binarized, arithmetically coded, and arithmetically decoded.

[Non Patent Literature 1]

ITU-T Recommendation H.264 “Advanced video coding for generic audiovisual services”, March 2010.

[Non Patent Literature 2]

JCT-VC “WD4: Working Draft 4 of High-Efficiency Video Coding”, JCTVC-F803, July 2011.

However, there is a demand for the conventional technique to achieve more efficient arithmetic coding and arithmetic decoding of the last position information.

In view of this, one non-limiting and exemplary embodiment provides an image coding method which allows efficient arithmetic coding and arithmetic decoding of the last position information.

An image coding method according to an aspect of the present disclosure is an image coding method for coding last position information indicating a horizontal position and a vertical position of a last non-zero coefficient in a predetermined order in a current block to be coded, the image coding method including: binarizing a first component and a second component to generate a first binary signal and a second binary signal, respectively, the first component being one of a horizontal component and a vertical component which are included in the last position information, and the second component being the other of the horizontal component and the vertical component; coding a first partial signal and a second partial signal by first arithmetic coding, and coding a third partial signal and a fourth partial signal by second arithmetic coding different from the first arithmetic coding, the first partial signal being a part of the first binary signal, the second partial signal being a part of the second binary signal, the third partial signal being another part of the first binary signal, and the fourth partial signal being another part of the second binary signal; and placing the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal in a bit stream, wherein in the placing, (i) the coded second partial signal is placed next to the coded first partial signal, or (ii) the coded fourth partial signal is placed next to the coded third partial signal.

It is to be noted that this general aspect may be implemented using a system, an apparatus, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or any combination of systems, apparatuses, integrated circuits, computer programs, or computer-readable recording media.

With the image coding method according to an aspect of the present disclosure, it is possible to arithmetically code and arithmetically decode the last position information efficiently.

The inventors have found the following matter regarding the arithmetic coding and arithmetic decoding of the last position information described in the “Background” section.

It is to be noted that in the following description, the last position information indicates a horizontal position and a vertical position of the last non-zero coefficient in a predetermined order in a current block. Here, the last position information includes a horizontal component (hereinafter referred to as “X component”) and a vertical component (hereinafter referred to as “Y component”). The X component indicates a horizontal position in the current block. The Y component indicates a vertical position in the current block.

1 FIG. 2 FIG. 1 FIG. 1000 1000 1001 1002 1003 1004 is a block diagram showing an example of a configuration of an image decoding apparatusaccording to the underlying knowledge.is a flowchart showing an example of an image decoding method according to the underlying knowledge. As shown in, the image decoding apparatusincludes a first decoding unit, a second decoding unit, a decoding control unit, and a reconstructing unit.

1000 1000 1001 1002 1003 The image decoding apparatusobtains a bit stream BS which includes the last position information. Then, the image decoding apparatusinputs the bit stream BS to the first decoding unit, the second decoding unit, and the decoding control unit.

1003 The decoding control unitmanages whether each signal in the obtained bit stream BS is the X component or the Y component of the last position information.

1001 1001 1001 The first decoding unitarithmetically decodes a prefix part of the X component of the last position information included in the bit stream BS (S). More specifically, the first decoding unitdecodes the prefix part of the X component by context adaptive binary arithmetic decoding. Here, the prefix part is a part of a binary signal of the X component or the Y component, which is coded by context adaptive binary arithmetic coding.

1001 1002 Next, the first decoding unitdetermines whether or not the binary signal of the X component includes a suffix part (S). The suffix part is a part of the binary signal of the X component or the Y component, which is coded by bypass coding.

3 FIG.A 3 FIG.D 1001 The prefix part and the suffix part are determined according to each value (hereinafter referred also to as “last value”) of the X component and the Y component as shown into, for example. Thus, with a predetermined method, the first decoding unitcan determine whether or not the binary signal of the X component includes the suffix part.

3 FIG.A 1001 More specifically, when the size of a transform block (hereinafter referred to as “transform size”) is 4×4, for example, the binary signal of the X component includes the prefix part only and does not include the suffix part regardless of the last value as shown in. Thus, the first decoding unitdetermines that the binary signal of the X component does not include the suffix part when the size of a block to be decoded is 4×4.

1001 1001 3 FIG.B In the case where the transform size is 8×8, for example, the first decoding unitdetermines that the decoded binary signal of the X component does not include the suffix part when any of binary symbol values up to the binary symbol value of the 4th bit of the binary signal of the X component is “1” as shown in. On the other hand, the first decoding unitdetermines that the decoded binary signal of the X component includes a suffix part having a fixed length of 2 bits when the binary symbol values up to the binary symbol value of the 4th bit of the binary signal of the X component are all “0”.

1001 1001 3 FIG.C In the case where the transform size is 16×16, for example, the first decoding unitdetermines that the decoded binary signal of the X component does not include the suffix part when any of the binary symbol values up to the binary symbol value of the 8th bit of the binary signal of the X component is “1” as shown in. On the other hand, the first decoding unitdetermines that the decoded binary signal of the X component includes a suffix part having a fixed length of 3 bits when the binary symbol values up to the binary symbol value of the 8th bit of the binary signal of the X component are all “0”.

1001 1001 3 FIG.D In the case where the transform size is 32×32, for example, the first decoding unitdetermines that the decoded binary signal of the X component does not include the suffix part when any of binary symbol values up to the binary symbol value of the 16th bit of the binary signal of the X component is “1” as shown in. On the other hand, the first decoding unitdetermines that the decoded binary signal of the X component includes a suffix part having a fixed length of 4 bits when the binary symbol values up to the binary symbol value of the 16th bit of the binary signal of the X component are all “0”.

1002 1002 1003 1002 1002 Here, when the binary signal of the X component includes the suffix part (Yes in S), the second decoding unitarithmetically decodes the suffix part having a predetermined, fixed bit length (S). More specifically, the second decoding unitarithmetically decodes the suffix part of the X component by bypass decoding. On the other hand, when the binary signal of the X component does not include the suffix part (No in S), the decoding process for the suffix part is skipped.

1004 1004 1004 1004 The reconstructing unitreconstructs the X component of the last position information using the prefix part and the suffix part which have been decoded (S). More specifically, when the binary signal of the X component includes the suffix part, the reconstructing unitreconstructs the X component by debinarizing the binary signal including the decoded prefix part and suffix part. On the other hand, when the binary signal of the X component does not include the suffix part, the reconstructing unitreconstructs the X component by debinarizing the binary signal including the decoded prefix part.

1001 1001 1005 1001 1002 1006 Next, the first decoding unitarithmetically decodes the prefix part of the Y component of the last position information as in Step S(S). After that, the first decoding unitdetermines whether or not the binary signal of the Y component includes the suffix part as in Step S(S).

1006 1002 1003 1007 1006 Here, when the binary signal of the Y component includes the suffix part (Yes in S), the second decoding unitarithmetically decodes the suffix part having a predetermined fixed length as in Step S(S). On the other hand, when the binary signal of the Y component does not include the suffix part (No in S), the decoding process for the suffix part is skipped.

1004 1004 1008 1004 1004 Lastly, the reconstructing unitreconstructs the Y component of the last position information as in Step S(S). More specifically, when the binary signal of the Y component includes the suffix part, the reconstructing unitreconstructs the Y component by debinarizing the binary signal including the decoded prefix part and suffix part. On the other hand, when the binary signal of the Y component does not include the suffix part, the reconstructing unitreconstructs the Y component by debinarizing the binary signal including the decoded prefix part.

This is the manner in which the X component and the Y component included in the last position information are reconstructed.

4 FIG. 6 FIG. Next, variable-length coding and variable-length decoding will be described. H.264 employs context adaptive binary arithmetic coding (CABAC) as one of variable-length coding methods. The prefix part is coded by CABAC. In contrast, the suffix part is coded by bypass coding, which is arithmetic coding in which a fixed probability (e.g., “0.5”) is used. Hereinafter, context adaptive binary arithmetic decoding and bypass decoding will be described usingto.

4 FIG. 4 FIG. 4 FIG. is a flowchart showing context adaptive binary arithmetic decoding. It is to be noted thathas been excerpted from Non Patent Literature 1. Unless otherwise specified, the description ofis as given in Non Patent Literature 1.

With the arithmetic decoding, first, context (ctxIdx) is inputted which is determined based on the signal type of a current signal to be decoded.

2001 Next, the following process is performed in Step S.

First, qCodIRangeIdx is calculated from a first parameter codIRange indicating a current state of arithmetic decoding. Furthermore, pStateIdx is obtained which is a state value corresponding to ctxIdx. Then, codIRangeLPS corresponding to the two values (qCodIRangeIdx and pStateIdx) is obtained by reference to a table (rangeTableLPS).

It is to be noted that codIRangeLPS indicates a state of arithmetic decoding when LPS has occurred in a state of arithmetic decoding indicated by the first parameter codIRange. LPS specifies one of the symbols “0” and “1” which has a lower probability of occurrence.

Furthermore, a value obtained by subtracting the above-mentioned codIRangeLPS from the current codIRange is set to codIRange.

2002 Next, in Step S, a comparison is made between codIRange and a second parameter codIOffset which indicates a state of arithmetic decoding.

2002 2003 Here, when codIOffset is greater than or equal to codIRange (Yes in S), the following process is performed in Step S.

First, it is determined that LPS has occurred, and a value different from vaIMPS (“0” when vaIMPS=1, and “1” when vaIMPS=0) is set to binVal that is a decoding output value. vaIMPS indicates a specific value of MPS (“0” or “1”). MPS specifies one of the binary symbol values “0” and “1” which has a higher probability of occurrence.

2001 Furthermore, a value obtained by subtracting codIRange from the current codIOffset is set to the second parameter codIOffset that indicates a state of arithmetic decoding. Furthermore, the value of codIRangeLPS which has been set in Step Sis set to the first parameter codIRange that indicates a state of arithmetic decoding.

2005 Next, in Step S, whether or not the value of pStateIdx is “0” is determined.

2005 2006 2005 2007 Here, when the value of pStateIdx is “0” (Yes in S), it means that the probability of LPS is greater than the probability of MPS. Thus, the value of vaIMPS is switched over (i.e., “0” is set when vaIMPS=1, and “1” is set when vaIMPS=0) (Step S). On the other hand, when the value of pStateIdx is not “0” (No in S), the value of pStateIdx is updated based on a transform table transIdxLPS that is referred to when LPS occurs (Step S).

2002 2004 Furthermore, when codIOffset is smaller than codIRange (No in S), it is determined that MPS has occurred. Thus, vaIMPS is set to binVal that is a decoding output value, and the value of pStateIdx is updated based on a transform table transIdxMPS that is referred to when MPS occurs (Step S).

2008 Lastly, normalization (RenormD) is performed (Step S), and the arithmetic decoding finishes.

As shown above, with the context adaptive binary arithmetic decoding, multiple probabilities of symbol occurrence, which are probabilities of occurrence of binary symbols, are held in association with context indices. The contexts are switched according to a condition (e.g., value of an adjacent block), and thus, it is necessary to maintain the processing order.

5 FIG. 5 FIG. 5 FIG. is a flowchart showing bypass decoding. It is to be noted thathas been excerpted from Non Patent Literature 1. Unless otherwise specified, the description ofis as given in Non Patent Literature 1.

3001 First, the second parameter codIOffset that indicates a current state of arithmetic decoding is left-shifted (doubled). Furthermore, one bit is read out from the bit stream, and when the read-out bit is “1”, 1 is added to codIOffset (Step S).

3002 3003 3002 3004 Next, when codIOffset is greater than or equal to the first parameter codIRange that indicates a state of arithmetic decoding (Yes in S), “1” is set to binVal that is a decoding output value, and a value obtained by subtracting codIRange from the current codIOffset is set to codIOffset (Step S). On the other hand, when codIOffset is smaller than the first parameter codIRange that indicates a state of arithmetic decoding (No in S), “0” is set to binVal that is a decoding output value (Step S).

6 FIG. 4 FIG. 6 FIG. 6 FIG. 2008 is a flowchart for describing in detail the normalization (RenormD) shown in Step Sin.has been excerpted from Non Patent Literature 1. Unless otherwise specified, the description ofis as given in Non Patent Literature 1.

4001 4002 When the first parameter codIRange that indicates a state of arithmetic decoding has become smaller than 0x100 (in base 16: 256 (in base 10)) (Yes in S), codIRange is left-shifted (doubled). Furthermore, the second parameter codIOffset that indicates a state of arithmetic decoding is left-shifted (doubled). Moreover, one bit is read out from the bit stream, and when the read-out bit is “1”, 1 is added to codIOffset (Step S).

4002 4001 When codIRange eventually reaches 256 or greater by this process in Step S(No in S), the normalization finishes.

This is the manner in which the arithmetic decoding is performed.

However, with the above underlying knowledge, the X component and the Y component included in the last position information are decoded in sequence. That is to say, the X component and the Y component are placed one after the other in the bit stream. Therefore, when the last position information is to be arithmetically decoded, context adaptive binary arithmetic decoding and bypass decoding are alternately performed. This means that switching between the arithmetic decoding methods occurs many times, which hinders efficient arithmetic decoding of the last position information.

In view of the foregoing, an image coding method according to an aspect of the present disclosure is an image coding method for coding last position information indicating a horizontal position and a vertical position of a last non-zero coefficient in a predetermined order in a current block to be coded, the image coding method including: binarizing a first component and a second component to generate a first binary signal and a second binary signal, respectively, the first component being one of a horizontal component and a vertical component which are included in the last position information, and the second component being the other of the horizontal component and the vertical component; coding a first partial signal and a second partial signal by first arithmetic coding, and coding a third partial signal and a fourth partial signal by second arithmetic coding different from the first arithmetic coding, the first partial signal being a part of the first binary signal, the second partial signal being a part of the second binary signal, the third partial signal being another part of the first binary signal, and the fourth partial signal being another part of the second binary signal; and placing the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal in a bit stream, wherein in the placing, (i) the coded second partial signal is placed next to the coded first partial signal, or (ii) the coded fourth partial signal is placed next to the coded third partial signal.

With this, in the bit stream, a coded partial signal is followed by a partial signal which has been coded by the same arithmetic coding as the preceding partial signal. Thus, when the arithmetically coded last position information is decoded, it is possible to reduce the number of times the arithmetic decoding methods are switched as compared to the case where the partial signals arithmetically coded by different methods are alternately placed. In other words, it is possible to output a bit stream from which the last position information can be efficiently decoded.

For example, the first arithmetic coding may be context adaptive binary arithmetic coding in which a variable probability updated based on a coded signal is used, and in the placing, the coded second partial signal may be placed next to the coded first partial signal.

With this, context adaptive binary arithmetic coding can be used as the first arithmetic coding. This makes it possible to output a bit stream from which two coded partial signals can be efficiently decoded in series by context adaptive binary arithmetic decoding.

For example, the second arithmetic coding may be bypass coding in which a fixed probability is used, and in the placing, the coded fourth partial signal may be placed next to the coded third partial signal.

With this, bypass coding can be used as the first arithmetic coding. It is to be noted that bypass decoding makes parallel processing easier because the variable probability is not used. This makes it possible to output a bit stream from which two coded partial signals can be efficiently decoded in series or in parallel by bypass decoding.

For example, the first arithmetic coding may be context adaptive binary arithmetic coding in which a variable probability updated based on a coded signal is used, the second arithmetic coding may be bypass coding in which a fixed probability is used, and in the placing, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal may be placed in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal.

With this, two partial signals coded by bypass coding can be placed next to two partial signals coded by context adaptive binary arithmetic coding. This makes it possible to further reduce the number of times the arithmetic decoding methods are switched when the last position information is decoded. In other words, it is possible to output a bit stream from which the last position information can be more efficiently decoded.

For example, the first arithmetic coding may be context adaptive binary arithmetic coding in which a variable probability updated based on a coded signal is used, the second arithmetic coding may be bypass coding in which a fixed probability is used, and in the placing, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal may be placed in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded fourth partial signal, and the coded third partial signal.

With this, two partial signals coded by bypass coding can be placed next to two partial signals coded by context adaptive binary arithmetic coding. This makes it possible to further reduce the number of times the arithmetic decoding methods are switched when the last position information is decoded. In other words, it is possible to output a bit stream from which the last position information can be more efficiently decoded.

Furthermore, with this, the coded fourth partial signal is placed next to the coded second partial signal, which makes it possible to output a bit stream from which the second binary signal can be obtained by a series of decoding processes.

For example, the image coding method may further include: switching a coding process to either a first coding process compliant with a first standard or a second coding process compliant with a second standard; and adding, to the bit stream, identification information indicating either the first standard or the second standard with which the coding process switched to is compliant, wherein when the coding process is switched to the first coding process, the binarizing, the coding, and the placing may be performed as the first coding process.

This makes it possible to switch between the first coding process compliant with the first standard and the second coding process compliant with the second standard.

Furthermore, an image decoding method according to an aspect of the present disclosure is an image decoding method for decoding last position information indicating a horizontal position and a vertical position of a last non-zero coefficient in a predetermined order in a current block to be decoded, the image decoding method including: decoding, by first arithmetic decoding, a coded first partial signal and a coded second partial signal which are included in a bit stream, and decoding, by second arithmetic decoding different from the first arithmetic decoding, a coded third partial signal and a coded fourth partial signal which are included in the bit stream; and reconstructing a first component by debinarizing a first binary signal which includes the decoded first partial signal and the decoded third partial signal, and reconstructing a second component by debinarizing a second binary signal which includes the decoded second partial signal and the decoded fourth partial signal, the first component being one of a horizontal component and a vertical component which are included in the last position information, and the second component being the other of the horizontal component and the vertical component, wherein in the bit stream, (i) the coded second partial signal is placed next to the coded first partial signal, or (ii) the coded fourth partial signal is placed next to the coded third partial signal.

With this, the last position information can be reconstructed by decoding of the bit stream in which a coded partial signal is followed by a partial signal which has been coded by the same arithmetic coding as the preceding partial signal. This makes it possible to reduce the number of times the arithmetic decoding methods are switched as compared to the case of decoding a bit stream in which the partial signals arithmetically coded by different methods are alternately placed. In other words, the last position information can be efficiently decoded.

For example, in the bit stream, the coded second partial signal may be placed next to the coded first partial signal, and the first arithmetic decoding may be context adaptive binary arithmetic decoding in which a variable probability updated based on a decoded signal is used.

With this, context adaptive binary arithmetic decoding can be used as the first arithmetic decoding. This makes it possible to efficiently decode two coded partial signals in series by context adaptive binary arithmetic decoding.

For example, in the bit stream, the coded fourth partial signal may be placed next to the coded third partial signal, and the second arithmetic decoding may be bypass decoding in which a fixed probability is used.

With this, bypass decoding can be used as the first arithmetic decoding. It is to be noted that bypass decoding makes parallel processing easier because the variable probability is not used. This makes it possible to efficiently decode two coded partial signals in series or in parallel by bypass decoding.

For example, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal may be placed in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal, the first arithmetic decoding may be context adaptive binary arithmetic decoding in which a variable probability updated based on a decoded signal is used, and the second arithmetic decoding may be bypass decoding in which a fixed probability is used.

With this, it is possible to decode the bit stream in which two partial signals coded by bypass coding are placed next to two partial signals coded by context adaptive binary arithmetic coding. This makes it possible to further reduce the number of times the arithmetic decoding methods are switched when the last position information is decoded, thereby allowing more efficient decoding of the last position information.

For example, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal may be placed in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded fourth partial signal, and the coded third partial signal, the first arithmetic decoding may be context adaptive binary arithmetic decoding in which a variable probability updated based on a decoded signal is used, and the second arithmetic decoding may be bypass decoding in which a fixed probability is used.

With this, it is possible to decode the bit stream in which two partial signals coded by bypass coding are placed next to two partial signals coded by context adaptive binary arithmetic coding. This makes it possible to further reduce the number of times the arithmetic decoding methods are switched when the last position information is decoded, thereby allowing more efficient decoding of the last position information.

Furthermore, with this, the bit stream is coded in which the coded fourth partial signal is placed next to the coded second partial signal, thereby allowing the second binary signal to be obtained by a series of decoding processes.

For example, the image decoding method may further include switching a decoding process to either a first decoding process compliant with a first standard or a second decoding process compliant with a second standard, according to identification information which is added to the bit stream and indicates either the first standard or the second standard, wherein when the decoding process is switched to the first decoding process, the decoding and the reconstructing may be performed as the first decoding process.

This makes it possible to switch between the first decoding process compliant with the first standard and the second decoding process compliant with the second standard.

It is to be noted that these general and specific aspects may be implemented using a system, an apparatus, an integrated circuit, a computer program, or a computer-readable recording medium such as a CD-ROM, or any combination of systems, apparatuses, integrated circuits, computer programs, or computer-readable recording media.

Hereinafter, embodiments will be described in detail using the drawings.

It is to be noted that each of the embodiments described below shows a general or specific example. The numerical values, shapes, materials, structural elements, the arrangement and connection of the structural elements, steps, the processing order of the steps etc., shown in the following embodiments are mere examples, and are therefore not intended to limit the scope of the Claims. Furthermore, among the structural elements in the following embodiments, structural elements not recited in any one of the independent claims representing the most generic concepts are described as arbitrary structural elements.

7 FIG. 100 100 is a block diagram showing a functional configuration of an image decoding apparatusaccording to Embodiment 1. The image decoding apparatusdecodes the last position information. Described here is the case where the coded last position information includes a coded first partial signal, a coded second partial signal, a coded third partial signal, and a coded fourth partial signal.

7 FIG. 100 110 104 110 101 102 103 As shown in, the image decoding apparatusincludes an arithmetic decoding unitand a reconstructing unit. The arithmetic decoding unitincludes a first decoding unit, a second decoding unit, and a decoding control unit.

100 The image decoding apparatusobtains a bit stream BS which includes the coded last position information.

It is to be noted that in some cases the bit stream BS does not include the coded third partial signal or does not include the coded fourth partial signal. For example, the bit stream BS does not include the coded third partial signal or does not include the coded fourth partial signal when a block to be decoded is smaller than a predetermined size, or when the value (last value) of a first component or a second component included in the last position information is smaller than a predetermined value.

Each of the coded first partial signal and the coded second partial signal corresponds to a prefix part which has been coded by context adaptive binary arithmetic coding, for example. Each of the coded third partial signal and the coded fourth partial signal corresponds to a suffix part which has been coded by bypass coding, for example.

Here, in the bit stream BS, the coded second partial signal is placed next to the coded first partial signal, or, the coded fourth partial signal is placed next to the coded third partial signal.

More specifically, in the bit stream BS, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal are placed in the following order: the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal, for example. Furthermore, in the bit stream BS, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal may be placed in the following order: the coded first partial signal, the coded second partial signal, the coded fourth partial signal, and the coded third partial signal, for example.

101 101 The first decoding unitdecodes the coded first partial signal and the coded second partial signal by first arithmetic decoding. The first arithmetic decoding is context adaptive binary arithmetic decoding in which a variable probability updated based on a decoded signal is used, for example. In this case, the first decoding unitdecodes the coded first partial signal and the coded second partial signal by context adaptive binary arithmetic decoding. It is to be noted that the first arithmetic decoding need not be context adaptive binary arithmetic decoding.

102 102 102 The second decoding unitdecodes the coded third partial signal and the coded fourth partial signal by second arithmetic decoding. For example, the second arithmetic decoding is bypass decoding in which a fixed probability is used. In this case, the second decoding unitdecodes the coded third partial signal and the coded fourth partial signal by bypass decoding. In doing so, the second decoding unitmay decode the coded third partial signal and the coded fourth partial signal in parallel.

It is to be noted that the second arithmetic decoding need not be bypass decoding. More specifically, it is sufficient as long as the first arithmetic decoding and the second arithmetic decoding are different.

103 103 110 100 103 101 102 The decoding control unitmanages, for each part of the bit stream BS, whether the part is the X component or the Y component of the last position information. It is to be noted that the decoding control unitneed not be included in the arithmetic decoding unit. That is to say, the image decoding apparatusneed not include the decoding control unit. In this case, it is sufficient as long as the first decoding unitand the second decoding unitmanage the X component and the Y component.

104 104 The reconstructing unitreconstructs the first component that is one of the horizontal component and the vertical component included in the last position information, by debinarizing a first binary signal which includes the first partial signal and the third partial signal. Furthermore, the reconstructing unitreconstructs the second component that is the other of the horizontal component and the vertical component included in the last position information, by debinarizing a second binary signal which includes the second partial signal and the fourth partial signal.

8 FIG.A 8 FIG.B 100 Next, usingand, the following describes in detail operations of the image decoding apparatushaving the above configuration.

Hereinafter, it is assumed that the first component is the X component and the second component is the Y component. It is also assumed that each of the first partial signal and the second partial signal is the prefix part and each of the third partial signal and the fourth partial signal is the suffix part. Furthermore, it is assumed that the suffix flag of the X component and the suffix flag of the Y component are set “OFF” as the default value. It is to be noted that the suffix flag is an internal flag indicating whether or not the binary signal of its corresponding component of the last position information includes the suffix part.

8 FIG.A 8 FIG.A 100 is a flowchart showing an example of processing operations of the image decoding apparatusaccording to Embodiment 1. As for, the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the X component, and the coded suffix part of the Y component are consecutively placed in the bit stream BS in the following order: the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the X component, and the coded suffix part of the Y component. It is to be noted that in some cases the suffix part of each component is not included in the bit stream BS depending on the value of the component.

101 101 101 First, the first decoding unitdecodes, from the bit stream BS, the coded prefix part of the X component by context adaptive binary arithmetic decoding (S). For example, the first decoding unitarithmetically decodes the coded prefix part on a one bit-by-one bit basis until a predetermined maximum length is reached or until “1” is decoded.

101 102 101 Next, the first decoding unitdetermines whether or not the binary signal of the X component includes the suffix part (S). For example, the first decoding unitdetermines that the binary signal of the X component includes the suffix part when the prefix part has the predetermined maximum length and the binary symbol values included in the prefix part are all “0”.

9 FIG.B 9 FIG.C It is to be noted that the maximum length of the prefix part is predetermined according to the transform size, for example. For example, the maximum length of the prefix part is determined in the manner shown inor.

102 101 103 102 101 101 Here, when the binary signal of the X component includes the suffix part (Yes in S), the first decoding unitsets the suffix flag of the X component “ON” (S). On the other hand, when the binary signal of the X component does not include the suffix part (No in S), the first decoding unitdoes not set the suffix flag of the X component “ON”. In other words, the suffix flag of the X component remains “OFF”, which is the default value. It is to be noted that the first decoding unitmay set the suffix flag of the X component “OFF” here.

101 104 101 Next, the first decoding unitdecodes, by context adaptive binary arithmetic decoding, the coded prefix part of the Y component placed next to the coded prefix part of the X component (S). More specifically, the first decoding unitdecodes the prefix part of the Y component in the same manner as the decoding of the prefix part of the X component.

101 105 101 After that, the first decoding unitdetermines whether or not the binary signal of the Y component includes the suffix part (S). More specifically, the first decoding unitdetermines whether or not the binary signal of the Y component includes the suffix part in the same manner as the determination as to whether or not the binary signal of the X component includes the suffix part.

105 101 106 105 101 Here, when the binary signal of the Y component includes the suffix part (Yes in S), the first decoding unitsets the suffix flag of the Y component “ON” (S). On the other hand, when the binary signal of the Y component does not include the suffix part (No in S), the first decoding unitdoes not set the suffix flag of the Y component “ON”.

102 107 107 102 108 107 108 Next, the second decoding unitdetermines whether or not the suffix flag of the X component is set “ON” (S). Here, when the suffix flag of the X component is set “ON” (Yes in S), the second decoding unitdecodes, by bypass decoding, the coded suffix part of the X component placed next to the coded prefix part of the Y component (S). On the other hand, when the suffix flag of the X component is not set “ON” (No in S), Step Sis skipped.

104 109 104 3 FIG.B The reconstructing unitreconstructs the X component of the last position information by debinarizing the binary signal of the X component which includes both the prefix part and the suffix part or which includes the prefix part only (S). For example, when the value of the X component is binarized as shown in, the reconstructing unitreconstructs the X component value “5” by debinarizing the binary signal “000010”.

102 110 110 102 111 110 111 Next, the second decoding unitdetermines whether or not the suffix flag of the Y component is set “ON” (S). Here, when the suffix flag of the Y component is set “ON” (Yes in S), the second decoding unitdecodes, by bypass decoding, the coded suffix part of the Y component placed next to the coded suffix part of the X component or placed next to the coded prefix part of the Y component (S). On the other hand, when the suffix flag of the Y component is not set “ON” (No in S), Step Sis skipped.

104 112 Lastly, the reconstructing unitreconstructs the Y component of the last position information by debinarizing the binary signal of the Y component which includes both the prefix part and the suffix part or which includes the prefix part only (S).

102 111 108 102 102 8 FIG.A It is to be noted that although the second decoding unitindecodes the suffix part of the Y component (S) after decoding the suffix part of the X component (S), the second decoding unitmay decode the suffix part of the X component and the suffix part of the Y component in parallel. This allows the second decoding unitto arithmetically decode the last position information at a higher speed.

8 FIG.A Next, the following describes the case where the prefix part and the suffix part of each component are placed in the bit stream in an order different from that in.

8 FIG.B 8 FIG.B 8 FIG.A 8 FIG.A 100 is a flowchart showing another example of processing operations of the image decoding apparatusaccording to Embodiment 1. It is to be noted that in, the processes performed in steps denoted by the same reference signs as those inare basically the same as the processes described in.

8 FIG.B 8 FIG.A As for, the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the X component, and the coded suffix part of the Y component are consecutively placed in the bit stream BS in the following order: the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the Y component, and the coded suffix part of the X component. It is to be noted that in some cases the suffix part of each component is not included in the bit stream BS depending on the value of the component, as in the case of.

101 101 101 102 First, the first decoding unitdecodes the coded prefix part of the X component by context adaptive binary arithmetic decoding (S). Then, the first decoding unitdetermines whether or not the binary signal of the X component includes the suffix part (S).

102 101 103 102 101 Here, when the binary signal of the X component includes the suffix part (Yes in S), the first decoding unitsets the suffix flag of the X component “ON” (S). On the other hand, when the binary signal of the X component does not include the suffix part (No in S), the first decoding unitdoes not set the suffix flag of the X component “ON”.

101 104 101 105 Next, the first decoding unitdecodes, by context adaptive binary arithmetic decoding, the coded prefix part of the Y component placed next to the coded prefix part of the X component (S). Then, the first decoding unitdetermines whether or not the binary signal of the Y component includes the suffix part (S).

105 102 111 105 111 Here, when the binary signal of the Y component includes the suffix part (Yes in S), the second decoding unitdecodes, by bypass decoding, the coded suffix part of the Y component placed next to the coded prefix part of the Y component (S). On the other hand, when the binary signal of the Y component does not include the suffix part (No in S), Step Sis skipped.

104 112 Next, the reconstructing unitreconstructs the Y component of the last position information by debinarizing the binary signal of the Y component which includes both the prefix part and the suffix part or which includes the prefix part only (S).

102 107 107 102 108 107 108 After that, the second decoding unitdetermines whether or not the suffix flag of the X component is set “ON” (S). Here, when the suffix flag of the X component is set “ON” (Yes in S), the second decoding unitdecodes, by bypass decoding, the coded suffix part of the X component placed next to the coded prefix part or suffix part of the Y component (S). On the other hand, when the suffix flag of the X component is not set “ON” (No in S), Step Sis skipped.

104 109 Lastly, the reconstructing unitreconstructs the X component of the last position information by debinarizing the binary signal of the X component which includes both the prefix part and the suffix part or which includes the prefix part only (S).

By consecutively decoding the prefix part and the suffix part of the Y component in the above-described manner, it is possible to reconstruct the Y component without holding, in a memory, information indicating whether or not the binary signal of the Y component includes the suffix part (here, the suffix flag of the Y component). This reduces the capacity required of the memory.

8 FIG.A 8 FIG.B 102 105 103 106 107 110 It is to be noted that in the flowcharts shown inand, it is not necessary to perform the determination regarding the suffix parts (Sand S), the setting of the suffix flags (Sand S), nor the determination regarding the suffix flags (Sand S) when it is determined in advance based on information included in the bit stream, for example, that the binary signals of the X component and the Y component each include the suffix part.

108 111 Next, the following describes an example of the decoding process on the coded suffix parts of the X component and the Y component (Sand S). Described here is the case where the suffix parts are binarized by Golomb-Rice coding.

With the Golomb-Rice coding, the length of each suffix part is not fixed. The suffix part can be divided into two parts, the first half and the second half.

The second half is a fixed-length part having a length indicated by a rice parameter (hereinafter referred to as “RP”).

RP The first half can be represented by: “1” that increases in the unit of a number representable by 2 to the RPth power (2) (e.g., in the unit of “4” when RP is “2”); and “0” that is set at the last bit position. More specifically, when RP is “2”, the length of the first half increases by 1 bit for each unit of 2 to the RPth power as follows: 0, 0, 0, 0, 10, 10, 10, 10, 110, 110, 110, 110, . . . .

It is to be noted that here, the amount of information to be represented by the suffix part is known, and thus it is possible to omit the last “0” of the first half when the first half has the maximum length. For example, when RP is “2” and the maximum amount of information is “12”, the first half can be represented by any one of 0, 0, 0, 0, 10, 10, 10, 10, 11, 11, 11, and 11. By omitting the last “0” of the first half in this manner, the coding amount of the binary signal can be reduced by 1 bit.

The maximum amount of information can be represented by the difference between the length in the transform size and the length of the prefix part. This reduces redundant bit(s).

9 FIG.D 9 FIG.E It is sufficient as long as RP is predetermined according to the transform size as shown inor, for example. This makes it possible to represent the suffix part with a binary signal having a length adapted to the transform size, and thus, the coding efficiency can be increased.

9 FIG.A 9 FIG.A 102 102 The following describes, using, operations of the second decoding unitfor decoding the suffix part binarized by Golomb-Rice coding as described above.is a flowchart showing an example of processing operations of the second decoding unitaccording to Embodiment 1.

102 201 102 9 FIG.D 9 FIG.E First, the second decoding unitsets an RP value (S). More specifically, the second decoding unitrefers to a predetermined table, for example, to set the RP value. The predetermined table in this case is a table shown inor, for example.

102 10 FIG.A 10 FIG.D It is to be noted that the second decoding unitmay set the RP value without referring to the table. The setting of the RP value will be described later in detail usingto.

102 202 102 Next, the second decoding unitsets a Max value (S). Here, the Max value indicates the maximum value of the length of the first half of the Golomb-Rice code. More specifically, the Max value indicates the shortest length of the binary signal that can represent a value obtained by subtracting the maximum length of the prefix part from the maximum value of the last value. Thus, the second decoding unitderives the Max value by (i) subtracting the length of the prefix part from the maximum value of the last value and (ii) dividing the resultant value by 2 to the RPth power or performing a right shift operation on the resultant value by RP bit(s).

9 FIG.B 9 FIG.C It is to be noted that the maximum length of the prefix part may be varied according to the transform size as shown inor.

102 203 Next, the second decoding unitdecodes, from the bit stream BS, a signal corresponding to 1 bit of the Golomb-Rice code by bypass decoding, and increments the count value (default is “0”) by 1 (S).

204 206 Here, when the decoded signal corresponding to 1 bit is “0” (Yes in S), the decoding of the first half of the Golomb-Rice code finishes, and the process proceeds to Step S.

204 205 205 203 102 On the other hand, when the decoded signal is not “0” (when the decoded signal is “1”) (No in S), it is determined whether or not the count value is equal to the Max value (S). Here, when the count value is not equal to the Max value (No in S), the process returns to Step S. More specifically, the second decoding unitdecodes a signal corresponding to the next 1 bit of the Golomb-Rice code by bypass decoding.

205 206 On the other hand, when the count value is equal to the Max value (Yes in S), the decoding of the first half of the suffix part finishes, and the process proceeds to Step S.

102 206 Next, the second decoding unitdecodes the second half of the Golomb-Rice code (a binary signal having a fixed length of RP bit(s)) by bypass decoding (S).

102 207 Lastly, the second decoding unitreconstructs the value represented by Golomb-Rice coding (S). Here, the value is reconstructed by adding up the second half of the Golomb-Rice code and a value obtained by shifting, to the left by the RP bit(s), a value obtained by subtracting 1 from the value represented by the first half of the Golomb-Rice code.

102 It is to be noted that in some cases the value of the binary signal of the second half is binarized in the form of a reversed value. In such cases, the second decoding unitperforms the reconstruction with this reverse taken into account. It is to be noted that it is sufficient as long as the decoding apparatus and the coding apparatus determine in advance whether or not the value of the binary signal is to be reversed. Neither the coding efficiency nor the processing load is affected regardless of whether or not the value of the binary signal is reversed.

10 FIG.A 10 FIG.D Next, the following describes, usingto, a method of determining the RP value and the maximum length of the prefix part.

10 FIG.A shows a method of determining the RP value and the maximum length of the prefix part according to the transform size.

102 301 102 302 102 303 9 FIG.D 9 FIG.E 9 FIG.B 9 FIG.C First, the second decoding unitobtains the transform size (S). Then, the second decoding unitrefers to a table as shown inorindicating a relationship between the transform size and the RP value, to determine the RP value associated with the obtained transform size (S). Furthermore, the second decoding unitrefers to a table as shown inorindicating a relationship between the transform size and the maximum length of the prefix part, to determine the maximum length of the prefix part (S).

10 FIG.B shows a method of determining the RP value and the maximum length of the prefix part according to prediction information.

102 311 First, the second decoding unitobtains prediction information (S). The prediction information is information related to prediction of a transform block which is a current block to be decoded. For example, the prediction information indicates whether the transform block is to be decoded by intra prediction or inter prediction. Furthermore, for example, the prediction information may be information indicating a prediction direction in intra prediction.

102 312 102 102 Next, the second decoding unitdetermines the RP value based on the prediction information (S). For example, it is known that in the case of inter prediction, there are generally less high frequency components than in intra prediction. Thus, when the prediction information indicates inter prediction, it is sufficient as long as the second decoding unitdetermines such an RP value that allows the X component and the Y component having small values to be represented by short binary signals. More specifically, when the prediction information indicates inter prediction, it is sufficient as long as the second decoding unitdetermines an RP value smaller than an RP value determined when the prediction information indicates intra prediction.

102 102 Furthermore, when the direction of intra prediction is the horizontal direction, it is generally expected that the Y component of the last position information is smaller than the X component. In view of this, when the prediction direction of intra prediction is the horizontal direction, it is sufficient as long as the second decoding unitdetermines, as the RP value of the Y component, an RP value smaller than the RP value of the X component. It is to be noted that when the prediction direction of intra prediction is the vertical direction, it is sufficient as long as the second decoding unitdetermines, as the RP value of the X component, an RP value smaller than the RP value of the Y component.

102 313 Lastly, the second decoding unitdetermines the maximum length of the prefix part based on the prediction information (S).

102 As described above, the second decoding unitcan vary the code length of the binary signal according to the prediction information, and thus, the coding efficiency can be increased.

10 FIG.C shows a method of determining the RP value and the maximum length of the prefix part according to statistical information.

102 321 First, the second decoding unitobtains statistical information (S). The statistical information is, for example, information on statistics of the length of the binary signal of the X component or the Y component included in the last position information of a previously decoded block.

102 322 102 323 Next, the second decoding unitdetermines the RP value based on the statistical information (S). Lastly, the second decoding unitdetermines the maximum length of the prefix part based on the statistical information (S).

102 As described above, the second decoding unitcan vary the code length of the binary signal according to the statistical information, and thus, the coding efficiency can be further increased.

10 FIG.D shows a method of determining the RP value and the maximum length of the prefix part according to a previously-decoded one of the X component and the Y component.

102 331 102 102 First, the second decoding unitobtains a previously-decoded one of the X component and the Y component (S). For example, the second decoding unitobtains a previously-decoded X component when decoding a coded Y component. Furthermore, for example, the second decoding unitmay obtain a previously-decoded Y component when decoding a coded X component.

102 332 102 Then, the second decoding unitdetermines, using the previously-decoded one of the X component and the Y component, the RP value of the other, yet-to-be-decoded one of the X component and the Y component (S). Generally, it is likely that the X component and the Y component have the same or similar values. Therefore, when the value of a previously-decoded X component is smaller than a certain value (e.g., half the transform size), for example, the second decoding unitdetermines, as the RP value of the Y component, a value smaller than the RP value of the X component.

102 333 Lastly, the second decoding unitdetermines, using the previously-decoded one of the X component and the Y component, the maximum length of the prefix part of the other, yet-to-be-decoded one of the X component and the Y component (S).

102 As described above, the second decoding unitcan vary the code length of the binary signal according to a previously-decoded one of the X component and the Y component, and thus, the coding efficiency can be further increased.

10 FIG.A 10 FIG.D 102 102 It is to be noted that the methods of determining the RP value and the maximum length of the prefix part shown intomay be used in combination. For example, when there is no information to refer to, the second decoding unitmay determine the RP value based on a predetermined table, whereas when there is information to refer to, the second decoding unitmay determine the RP value according to the information which can be referred to.

102 102 Moreover, the second decoding unitmay determine the maximum length of the prefix part in the same manner as the RP value. It is to be noted that when the values of the X component and the Y component are predicted to be large, it is sufficient as long as the second decoding unitdetermines the maximum length of the prefix part to be shorter than when the X component and the Y component are predicted to be small. This further increases the coding efficiency.

11 FIG.A 11 FIG.B Next, the following describes, usingand, a time period required for arithmetic decoding of the coded last position information.

11 FIG.A 11 FIG.A is a diagram for describing an example of arithmetic decoding according to Embodiment 1. As for, the following describes the case where the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the Y component, and the coded suffix part of the X component are included in the bit stream BS in this order.

11 FIG.A 11 FIG.A The part (a) ofshows an example of the case where the prefix part and the suffix part of each component are arithmetically decoded in sequence. As for the part (a) of, decoding of the prefix part of the X component of the last position information (LASTX_PREFIX), decoding of the prefix part of the Y component (LASTY_PREFIX), decoding of the suffix part of the Y component (LASTY_SUFFIX), and decoding of the suffix part of the X component (LASTX_SUFFIX) are performed in this order.

Here, one might consider arithmetically decoding the last position information in parallel in order to increase the processing speed of the arithmetic decoding. However, since the prefix part is decoded by context adaptive binary arithmetic decoding, it is difficult to perform arithmetic decoding in parallel. To be more specific, a variable probability (probability of symbol occurrence) which is updated based on a coded signal is used in the arithmetic decoding of the prefix part. This means that it is necessary to successively read and update the probability of symbol occurrence. Therefore, it is difficult to parallelize the arithmetic decoding of the prefix part.

On the other hand, it is relatively easy to parallelize the arithmetic decoding of the suffix part because the suffix part is decoded by bypass decoding. To be more specific, the variable probability updated based on a coded signal is not used in the arithmetic decoding of the suffix part, but a fixed probability (probability of symbol occurrence) is used. Therefore, it is relatively easy to parallelize the arithmetic decoding of the suffix part.

11 FIG.A In view of this, the arithmetic decoding of the suffix part may be parallelized bitwise as shown in the part (b) of. This increases the processing speed of the arithmetic decoding of the last position information.

11 FIG.A Moreover, when the process is to be further parallelized, information related to the suffix part may be obtained from the bit stream BS, and the arithmetic decoding of the suffix part may start before context adaptive binary arithmetic decoding is completed, as shown in the part (c) of, for example. This further increases the speed of decoding of the last position information.

11 FIG.B 11 FIG.B is a diagram for describing an example of arithmetic decoding according to a comparable example. As for, the following describes the case where the coded prefix part of the X component, the coded suffix part of the X component, the coded prefix part of the Y component, and the coded suffix part of the Y component are included in the bit stream BS in this order.

11 FIG.B 11 FIG.B 11 FIG.A 11 FIG.B 11 FIG.A The part (a) ofshows an example of the case where the prefix part and the suffix part of each component are arithmetically decoded in sequence. The processing time required in the case of the part (a) ofis equal to the processing time required in the case of the part (a) of. However, in the case of the part (a) of, the number of times switching is performed between context adaptive binary arithmetic decoding and bypass decoding is larger than in the case of the part (a) of.

11 FIG.B 11 FIG.B 11 FIG.B 11 FIG.B 11 FIG.A The part (b) ofis a diagram for describing an example of the case where the arithmetic decoding of the suffix part is parallelized bitwise. As for the part (b) of, bypass decoding of the suffix part is parallelized, and thus the processing time is shorter than in the part (a) of. However, the decoding of the suffix part of the X component and the decoding of the suffix part of the Y component cannot be parallelized. Thus, the processing time in the part (b) ofis longer than that in the part (b) of.

100 As described above, the image decoding apparatusaccording to Embodiment 1 can efficiently decode the last position information.

100 100 100 More specifically, the image decoding apparatuscan reconstruct the last position information by decoding the bit stream in which the coded binary signals of the X component and the Y component included in the last position information are placed after being classified into a group for context adaptive binary arithmetic decoding and a group for bypass decoding. This allows the image decoding apparatusto reduce the number of times the arithmetic decoding methods are switched. Moreover, the image decoding apparatuscan arithmetically decode the coded last position information at high speed because it is possible to group partial signals that are to be decoded by bypass decoding, which can be performed in parallel.

100 100 To be more specific, the image decoding apparatuscan reconstruct the last position information by decoding the bit stream in which a coded partial signal (e.g., the suffix part of the X component) is followed by a partial signal (e.g., the suffix part of the Y component) which has been coded by the same arithmetic coding as the preceding partial signal. Thus, the image decoding apparatuscan reduce the number of times the arithmetic decoding methods are switched and efficiently decode the last position information as compared to the case of decoding a bit stream in which partial signals which have been arithmetically coded by different methods are alternately placed.

9 FIG.B 9 FIG.E It is to be noted that the RP values and the maximum lengths of the prefix part shown intoare mere examples, and there may be different RP values and different maximum lengths of the prefix part. For example, the maximum length of the prefix part may be shorter and the suffix part may be longer. This further enables parallel arithmetic decoding and further increases the speed of arithmetic decoding.

It is to be noted that each of the structural elements in the present embodiment may be configured in the form of an exclusive hardware product, or may be implemented by executing a software program suitable for the structural element. Each structural element may be implemented by means of a program executing unit, such as a CPU or a processor, reading and executing the software program recorded on a recording medium such as a hard disk or a semiconductor memory. Here, the software program for implementing the image decoding apparatus according to the present embodiment is a program described below.

This program causes a computer to execute an image decoding method for decoding last position information indicating a horizontal position and a vertical position of a last non-zero coefficient in a predetermined order in a current block to be decoded, the image decoding method including: decoding, by first arithmetic decoding, a coded first partial signal and a coded second partial signal which are included in a bit stream, and decoding, by second arithmetic decoding different from the first arithmetic decoding, a coded third partial signal and a coded fourth partial signal which are included in the bit stream; and reconstructing a first component by debinarizing a first binary signal which includes the decoded first partial signal and the decoded third partial signal, and reconstructing a second component by debinarizing a second binary signal which includes the decoded second partial signal and the decoded fourth partial signal, the first component being one of a horizontal component and a vertical component which are included in the last position information, and the second component being the other of the horizontal component and the vertical component, wherein in the bit stream, (i) the coded second partial signal is placed next to the coded first partial signal, or (ii) the coded fourth partial signal is placed next to the coded third partial signal.

100 200 12 FIG. The image decoding apparatusaccording to Embodiment 1 may be included in an image decoding apparatus below.is a block diagram showing an example of a configuration of an image decoding apparatusaccording to a variation of Embodiment 1.

200 200 200 The image decoding apparatusdecodes coded image data generated by compression coding. For example, the image decoding apparatusreceives coded image data on a block-by-block basis as a current signal to be decoded. The image decoding apparatusperforms variable-length decoding, inverse quantization, and inverse transform on the received current signal to reconstruct image data.

12 FIG. 200 210 220 225 230 240 250 260 270 As shown in, the image decoding apparatusincludes an entropy decoding unit, an inverse quantization and inverse transform unit, an adder, a deblocking filter, a memory, an intra prediction unit, a motion compensation unit, and an intra/inter switch.

210 210 260 The entropy decoding unitperforms variable-length decoding on an input signal (bit stream) to reconstruct quantized coefficients. Here, the input signal is a current signal to be decoded and corresponds to data on a block-by-block basis of the coded image data. The coded image data includes the coded last position information. Furthermore, the entropy decoding unitobtains motion data from the input signal and outputs the motion data to the motion compensation unit.

100 210 210 It is to be noted that the image decoding apparatusaccording to Embodiment 1 corresponds to part of the entropy decoding unit. That is to say, the entropy decoding unitdecodes the coded last position information.

220 210 220 The inverse quantization and inverse transform unitperforms inverse quantization on the quantized coefficients reconstructed by the entropy decoding unit, to reconstruct transform coefficients. Then, the inverse quantization and inverse transform unitperforms inverse transform on the transform coefficients to reconstruct a prediction error.

225 The adderadds the prediction error and a prediction signal to generate a decoded image.

230 The deblocking filterapplies a deblocking filter to the decoded image. The resultant decoded image is outputted as a decoded signal.

240 240 The memoryis a memory for storing a reference image used in motion compensation. More specifically, the memorystores the decoded image to which the deblocking filter has been applied.

250 250 225 The intra prediction unitperforms intra prediction to generate a prediction signal (intra prediction signal). More specifically, the intra prediction unitgenerates an intra prediction signal by performing intra prediction by reference to an image neighboring the current block to be decoded (input signal) in the decoded image generated by the adder.

260 210 The motion compensation unitperforms motion compensation based on the motion data outputted by the entropy decoding unit, to generate a prediction signal (inter prediction signal).

270 225 The intra/inter switchselects either the intra prediction signal or the inter prediction signal, and outputs the selected signal to the adderas the prediction signal.

200 With the above configuration, the image decoding apparatusdecodes the coded image data generated by compression coding.

The following describes an image coding apparatus according to Embodiment 2 using the drawings.

13 FIG. 300 300 is a block diagram showing a functional configuration of an image coding apparatusaccording to Embodiment 2. The image coding apparatuscodes the last position information. Described here is the case where the binary signal of the first component (first binary signal) included in the last position information includes the first partial signal and the third partial signal, whereas the binary signal of the second component (second binary signal) included in the last position information includes the second partial signal and the fourth partial signal.

It is to be noted that the first component is one of the horizontal component and the vertical component, and the second component is the other of the horizontal component and the vertical component.

13 FIG. 300 310 320 330 320 321 322 323 As shown in, the image coding apparatusincludes a binarizing unit, an arithmetic coding unit, and a placing unit. The arithmetic coding unitincludes a first coding unit, a second coding unit, and a coding control unit.

310 The binarizing unitbinarizes the first component and the second component included in the last position information, to generate the first binary signal and the second binary signal.

321 The first coding unitcodes, by first arithmetic coding, the first partial signal that is a part of the first binary signal and the second partial signal that is a part of the second binary signal. The first arithmetic coding is, for example, context adaptive binary arithmetic coding in which a variable probability updated based on a coded signal is used. It is to be noted that the first arithmetic coding need not be context adaptive binary arithmetic coding.

322 The second coding unitcodes, by second arithmetic coding different from the first arithmetic coding, the third partial signal that is another part of the first binary signal and the fourth partial signal that is another part of the second binary signal. The second arithmetic coding is, for example, bypass coding in which a fixed probability is used. It is to be noted that the second arithmetic coding need not be bypass coding. That is to say, it is sufficient as long as the first arithmetic coding and the second arithmetic coding are different.

323 320 323 320 300 323 The coding control unitmanages which one of the first to fourth partial signals is the signal received by the arithmetic coding unit. It is to be noted that the coding control unitneed not be included in the arithmetic coding unit. That is to say, the image coding apparatusneed not include the coding control unit.

330 330 The placing unitplaces, in a bit stream, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal. Here, the placing unitplaces the coded second partial signal next to the coded first partial signal, or places the coded fourth partial signal next to the coded third partial signal.

330 330 More specifically, the placing unitmay place, for example, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal. Furthermore, the placing unitmay place, for example, the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal in the bit stream in the following order: the coded first partial signal, the coded second partial signal, the coded fourth partial signal, and the coded third partial signal.

14 FIG.A 14 FIG.B 300 Next, usingand, the following describes operations of the image coding apparatushaving the above configuration.

Hereinafter, it is assumed that the first component is the X component and the second component is the Y component. It is also assumed that each of the first partial signal and the second partial signal is the prefix part and each of the third partial signal and the fourth partial signal is the suffix part. Furthermore, it is assumed that the suffix flag of the X component and the suffix flag of the Y component are set “OFF” as the default value. It is to be noted that the suffix flag is an internal flag indicating whether or not the binary signal of its corresponding component of the last position information includes the suffix part.

14 FIG.A 14 FIG.A 8 FIG.A 300 is a flowchart showing an example of processing operations of the image coding apparatusaccording to Embodiment 2. To be more specific,shows a coding method for generating a bit stream which is decodable by the decoding method shown in.

310 401 310 15 FIG. First, the binarizing unitbinarizes each of the X component and the Y component of the last position information (S). More specifically, the binarizing unitbinarizes each of the X component and the Y component (last values) as shown in, for example. Here, the suffix part is binarized by Golomb-Rice coding.

321 402 Next, the first coding unitcodes, by context adaptive binary arithmetic coding, the prefix part of the X component included in the last position information (S).

4 FIG. Context adaptive binary arithmetic coding is coding corresponding to context adaptive binary arithmetic decoding shown in. With context adaptive binary arithmetic coding, contexts are switched according to a condition, and a probability of symbol occurrence corresponding to the context switched to is obtained. Then, a binary symbol is arithmetically coded using the obtained probability of symbol occurrence. Furthermore, the probability value corresponding to the context is updated according to the coded binary symbol value (see Non Patent Literature 1).

321 403 321 102 8 FIG.A Next, the first coding unitdetermines whether or not the binary signal of the X component includes the suffix part (S). More specifically, the first coding unitdetermines whether or not the binary signal of the X component includes the suffix part in the same manner as in Step Sin.

403 321 404 403 321 321 Here, when the binary signal of the X component includes the suffix part (Yes in S), the first coding unitsets the suffix flag of the X component “ON” (S). On the other hand, when the binary signal of the X component does not include the suffix part (No in S), the first coding unitdoes not set the suffix flag of the X component “ON”. In other words, the suffix flag of the X component remains “OFF”. It is to be noted that the first coding unitmay set the suffix flag of the X component “OFF” here.

321 405 321 406 Next, the first coding unitcodes, by context adaptive binary arithmetic coding, the prefix part of the Y component included in the last position information (S). After that, the first coding unitdetermines whether or not the binary signal of the Y component includes the suffix part (S).

406 321 407 406 321 Here, when the binary signal of the Y component includes the suffix part (Yes in S), the first coding unitsets the suffix flag of the Y component “ON” (S). On the other hand, when the binary signal of the Y component does not include the suffix part (No in S), the first coding unitdoes not set the suffix flag of the Y component “ON”.

322 408 408 322 409 408 409 Next, the second coding unitdetermines whether or not the suffix flag of the X component is set “ON” (S). Here, when the suffix flag of the X component is set “ON” (Yes in S), the second coding unitcodes the suffix part of the X component by bypass coding (S). On the other hand, when the suffix flag of the X component is not set “ON” (No in S), Step Sis skipped.

322 410 410 322 411 410 411 The second coding unitdetermines whether or not the suffix flag of the Y component is set “ON” (S). Here, when the suffix flag of the Y component is set “ON” (Yes in S), the second coding unitcodes the suffix part of the Y component by bypass coding (S). On the other hand, when the suffix flag of the Y component is not set “ON” (No in S), Step Sis skipped.

330 412 330 Lastly, the placing unitplaces, in the bit stream BS, the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the X component, and the coded suffix part of the Y component in this order (S). Here, the placing unitplaces, in the bit stream BS, the prefix part and the suffix part of each component in the order in which they have been coded.

14 FIG.A Next, the following describes the case where the prefix part and the suffix part of each component are placed in the bit stream in an order different from.

14 FIG.B 14 FIG.B 8 FIG.B 14 FIG.B 14 FIG.A 14 FIG.A 300 is a flowchart showing another example of processing operations of the image coding apparatusaccording to Embodiment 2. To be more specific,shows a coding method for generating a bit stream which is decodable by the decoding method shown in. It is to be noted that in, the processes performed in steps denoted by the same reference signs as those inare basically the same as the processes described in.

310 401 321 402 First, the binarizing unitbinarizes each of the X component and the Y component of the last position information (S). Next, the first coding unitcodes, by context adaptive binary arithmetic coding, the prefix part of the X component included in the last position information (S).

321 403 403 321 404 403 321 Next, the first coding unitdetermines whether or not the binary signal of the X component includes the suffix part (S). Here, when the binary signal of the X component includes the suffix part (Yes in S), the first coding unitsets the suffix flag of the X component “ON” (S). On the other hand, when the binary signal of the X component does not include the suffix part (No in S), the first coding unitdoes not set the suffix flag of the X component “ON”.

321 405 321 406 Then, the first coding unitcodes the prefix part of the Y component by context adaptive binary arithmetic coding (S). After that, the first coding unitdetermines whether or not the binary signal of the Y component includes the suffix part (S).

406 322 411 406 411 Here, when the binary signal of the Y component includes the suffix part (Yes in S), the second coding unitcodes the suffix part of the Y component by bypass coding (S). On the other hand, when the binary signal of the Y component does not include the suffix part (No in S), Step Sis skipped.

322 408 408 322 409 408 409 Next, the second coding unitdetermines whether or not the suffix flag of the X component is set “ON” (S). Here, when the suffix flag of the X component is set “ON” (Yes in S), the second coding unitcodes the suffix part of the X component by bypass coding (S). On the other hand, when the suffix flag of the X component is not set “ON” (No in S), Step Sis skipped.

330 512 330 Lastly, the placing unitplaces, in the bit stream BS, the coded prefix part of the X component, the coded prefix part of the Y component, the coded suffix part of the Y component, and the coded suffix part of the X component in this order (S). Here, the placing unitplaces, in the bit stream BS, the prefix part and the suffix part of each component in the order in which they have been coded.

14 FIG.A By consecutively coding the prefix part and the suffix part of the Y component in the above-described manner, it is possible to code the binary signal of the Y component without holding, in a memory, information indicating whether or not the binary signal of the Y component includes the suffix part (the suffix flag of the Y component in). This reduces the capacity required of the memory.

14 FIG.A 14 FIG.B 403 406 404 407 408 410 It is to be noted that in the flowcharts shown inand, it is not necessary to perform the determination regarding the suffix parts (Sand S), the setting of the suffix flags (Sand S), and the determination regarding the suffix flags (Sand S) when it is determined in advance that the binary signals of the X component and the Y component each include the suffix part.

15 FIG. Next, using, the following briefly describes a method of coding the prefix part and the suffix part included in the last position information.

15 FIG. 15 FIG. is a diagram showing an example of binary signals of the last position information when the block size is 16×16. In, the maximum length of the prefix part is “4” and RP is “2”.

321 321 When the prefix part is shorter than the maximum length of the prefix part, the first coding unitcodes, by context adaptive binary arithmetic coding, as many “0” as the number indicated by the value of the X component. Lastly, the first coding unitcodes “1” by context adaptive binary arithmetic coding. In this case, the binary signal of the X component does not include the suffix part, and thus the coding of the X component finishes here.

321 On the other hand, when the prefix part is longer than the maximum length of the prefix part, the first coding unitcodes, by context adaptive binary arithmetic coding, as many “0” as the number of the maximum length.

322 322 Next, the second coding unitcodes the first half of the suffix part. More specifically, the second coding unitadds “1” to the first half in the unit of the number representable by 2 to the RPth power (e.g., in the unit of “4” when RP is “2”), codes the resultant value, and lastly codes “0”.

322 322 322 That is to say, when the value of the X component is greater than or equal to 4 and less than 8, the second coding unitonly codes “0” as the first half. When the value of the X component is greater than or equal to 8 and less than 12, the second coding unitcodes “10” as the first half. When the value of the X component is greater than or equal to 12 and less than 16, the second coding unitcodes “110” as the first half.

15 FIG. It is to be noted that in the example of, the amount of information to be represented by the suffix part is “12” (16−4=12), and thus, when the value of the X component is greater than or equal to 12 and less than 16, instead of coding “110” as the first half, “11” which is obtained by omitting the last “0” of “110” is coded. This reduces the code length.

322 15 FIG. Next, the second coding unitcodes the second half of the suffix part. The second half is a fixed-length part having a length indicated by the RP value. In the example of, the second half indicates a value which is obtained by binarizing a number among the numbers up to 2 to the RPth power and outputting the resultant value from the number on the left to the number on the right. More specifically, the second half indicates a value obtained by binarizing 0, 1, 2, or 3. This is a mere example, and the coding efficiency is not affected in particular as long as there is consistency between the method used by the coding apparatus and the method used by the decoding apparatus.

14 FIG.A 14 FIG.B 11 FIG.A It is to be noted that even inand, it is possible to parallelize the coding of the suffix part and increase the speed of arithmetic coding as indescribed in Embodiment 1.

300 300 As described above, with the image coding apparatusaccording to the present embodiment, in a bit stream, a coded partial signal (e.g., the suffix part of the X component) is followed by a partial signal (e.g., the suffix part of the Y component) which has been coded by the same arithmetic coding as the preceding partial signal. Thus, when the arithmetically coded last position information is decoded, it is possible to reduce the number of times the arithmetic decoding methods are switched as compared to the case where the partial signals arithmetically coded by different methods are alternately placed. That is to say, the image coding apparatuscan output a bit stream from which the last position information can be efficiently decoded.

It is to be noted that each of the structural elements in the present embodiment may be configured in the form of an exclusive hardware product, or may be implemented by executing a software program suitable for the structural element. Each structural element may be implemented by means of a program executing unit, such as a CPU or a processor, reading and executing the software program recorded on a recording medium such as a hard disk or a semiconductor memory. Here, the software program for implementing the image coding apparatus according to the present embodiment is a program described below.

This program causes a computer to execute an image coding method for coding last position information indicating a horizontal position and a vertical position of a last non-zero coefficient in a predetermined order in a current block to be coded, the image coding method including: binarizing a first component and a second component to generate a first binary signal and a second binary signal, respectively, the first component being one of a horizontal component and a vertical component which are included in the last position information, and the second component being the other of the horizontal component and the vertical component; coding a first partial signal and a second partial signal by first arithmetic coding, and coding a third partial signal and a fourth partial signal by second arithmetic coding different from the first arithmetic coding, the first partial signal being a part of the first binary signal, the second partial signal being a part of the second binary signal, the third partial signal being another part of the first binary signal, and the fourth partial signal being another part of the second binary signal; and placing the coded first partial signal, the coded second partial signal, the coded third partial signal, and the coded fourth partial signal in a bit stream, wherein in the placing, (i) the coded second partial signal is placed next to the coded first partial signal, or (ii) the coded fourth partial signal is placed next to the coded third partial signal.

300 400 16 FIG. The image coding apparatusaccording to Embodiment 2 may be included in an image coding apparatus below.is a block diagram showing an example of a configuration of an image coding apparatusaccording to a variation of Embodiment 2.

400 400 400 The image coding apparatusperforms compression coding on image data. For example, the image coding apparatusreceives the image data on a block-by-block basis as an input signal. The image coding apparatusperforms transform, quantization, and variable-length coding on the input signal to generate a coded signal (bit stream).

16 FIG. 400 405 410 420 430 435 440 450 460 470 480 490 As shown in, the image coding apparatusincludes a subtractor, a transform and quantization unit, an entropy coding unit, an inverse quantization and inverse transform unit, an adder, a deblocking filter, a memory, an intra prediction unit, a motion estimation unit, a motion compensation unit, and an intra/inter switch.

405 The subtractorcalculates a difference between the input signal and the prediction signal as a prediction error.

410 410 410 The transform and quantization unittransforms the prediction error in the spatial domain to generate transform coefficients in the frequency domain. For example, the transform and quantization unitperforms discrete cosine transform (DCT) on the prediction error to generate the transform coefficients. Furthermore, the transform and quantization unitquantizes the transform coefficients to generate quantized coefficients.

420 420 470 The entropy coding unitperforms variable-length coding on the quantized coefficients to generate a coded signal. Furthermore, the entropy coding unitcodes motion data (e.g., motion vector) detected by the motion estimation unit, to output the coded signal with the motion data included therein.

300 420 420 It is to be noted that the image coding apparatusaccording to Embodiment 2 corresponds to part of the entropy coding unit. That is to say, the entropy coding unitcodes the last position information.

430 430 405 The inverse quantization and inverse transform unitperforms inverse quantization on the quantized coefficients to reconstruct transform coefficients. Furthermore, the inverse quantization and inverse transform unitperforms inverse transform on the reconstructed transform coefficients to reconstruct a prediction error. It is to be noted that the reconstructed prediction error lacks information due to the quantization and thus is not the same as the prediction error generated by the subtractor. In other words, the reconstructed prediction error contains a quantization error.

435 The adderadds up the reconstructed prediction error and a prediction signal to generate a local decoded image.

440 The deblocking filterapplies a deblocking filter to the local decoded image.

450 450 The memoryis a memory for storing a reference image used in motion compensation. More specifically, the memorystores the local decoded image to which the deblocking filter has been applied.

460 460 435 The intra prediction unitperforms intra prediction to generate a prediction signal (intra prediction signal). More specifically, the intra prediction unitgenerates an intra prediction signal by performing intra prediction by reference to an image neighboring the current block to be coded (input signal) in the local decoded image generated by the adder.

470 450 The motion estimation unitdetects motion data (e.g., motion vector) between the input signal and the reference image stored in the memory.

480 The motion compensation unitperforms motion compensation based on the motion data to generate a prediction signal (inter prediction signal).

490 405 435 The intra/inter switchselects either the intra prediction signal or the inter prediction signal, and outputs the selected signal to the subtractorand the adderas the prediction signal.

400 With the above configuration, the image coding apparatusperforms compression coding on the image data.

Although only some exemplary embodiments have been described above, the scope of the Claims of the present application is not limited to these embodiments. Those skilled in the art will readily appreciate that various modifications may be made in these exemplary embodiments and that other embodiments may be obtained by arbitrarily combining the structural elements of the embodiments without materially departing from the novel teachings and advantages of the subject matter recited in the appended Claims. Accordingly, all such modifications and other embodiments are included in the present disclosure.

For example, although each embodiment above has specifically described the decoding or coding of the last position information, it is also possible to decode and code the X component and the Y component of a motion vector in the same manner as that described above. More specifically, it is possible to perform coding and decoding without buffering information indicating whether or not the suffix part of the Y component is present, by placing a bypass-coded part including the suffix part of the Y component and a positive/negative code and a bypass-coded part including the suffix part of the X component and a positive/negative code next to the prefix part of the X component (context-adaptive-coded part) and the prefix part of the Y component (context-adaptive-coded part). It is to be noted that the details of motion vector information are described in detail in Non Patent Literature 1 and thus a description thereof is omitted here.

3 FIG.A 3 FIG.D Furthermore, although the suffix part is binarized by Golomb-Rice coding in each embodiment above, the suffix part may be binarized with a different method. For example, the suffix part may be binarized with a fixed length as shown into.

3 FIG.A 3 FIG.D 3 FIG.B Moreover, the method of binarizing the X component and the Y component in each embodiment above is a mere example, and they may be binarized with a different binarizing method. For example, into, the last value may be binarized with “0” and “1” reversed. More specifically, in, the last value “3” may be binarized into “1110”, for example.

Furthermore, although each embodiment above has shown the example where (i) the prefix part of the X component, the prefix part of the Y component, the suffix part of the X component, and the suffix part of the Y component are placed in this order or (ii) the prefix part of the X component, the prefix part of the Y component, the suffix part of the Y component, and the suffix part of the X component are placed in this order, the placing order of these prefix and suffix parts is not limited to this example. For example, the prefix part of the Y component and the prefix part of the X component may be placed in this order.

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 moving picture coding method (image coding method) and the moving picture decoding method (image 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 moving picture coding method (image coding method) and the moving picture decoding method (image decoding method) described in each of embodiments and systems using thereof will be described. The system has a feature of having an image coding and decoding apparatus that includes an image coding apparatus using the image coding method and an image decoding apparatus using the image decoding method. Other configurations in the system can be changed as appropriate depending on the cases.

17 FIG. 100 106 107 108 109 110 illustrates an overall configuration of a content providing system exfor implementing content distribution services. The area for providing communication services is divided into cells of desired size, and base stations ex, ex, ex, ex, and exwhich are fixed wireless stations are placed in each of the cells.

100 111 112 113 114 115 101 102 104 106 110 The content providing system exis connected to devices, such as a computer ex, a personal digital assistant (PDA) ex, a camera ex, a cellular phone exand a game machine ex, via the Internet ex, an Internet service provider ex, a telephone network ex, as well as the base stations exto ex, respectively.

100 104 106 110 17 FIG. However, the configuration of the content providing system exis not limited to the configuration shown in, 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 ex, rather than via the base stations exto exwhich are the fixed wireless stations. Furthermore, the devices may be interconnected to each other via a short distance wireless communication and others.

113 116 114 114 The camera ex, such as a digital video camera, is capable of capturing video. A camera ex, such as a digital camera, is capable of capturing both still images and video. Furthermore, the cellular phone exmay be the one that meets any of the standards such as Global System for Mobile Communications (GSM) (registered trademark), 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 exmay be a Personal Handyphone System (PHS).

100 103 113 104 109 113 103 103 111 112 113 114 115 In the content providing system ex, a streaming server exis connected to the camera exand others via the telephone network exand the base station ex, 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 exis coded as described above in each of embodiments (i.e., the camera functions as the image coding apparatus according to an aspect of the present disclosure), and the coded content is transmitted to the streaming server ex. On the other hand, the streaming server excarries out stream distribution of the transmitted content data to the clients upon their requests. The clients include the computer ex, the PDA ex, the camera ex, the cellular phone ex, and the game machine exthat 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 (i.e., functions as the image decoding apparatus according to an aspect of the present disclosure).

113 103 113 103 103 103 113 116 103 111 116 111 103 The captured data may be coded by the camera exor the streaming server exthat transmits the data, or the coding processes may be shared between the camera exand the streaming server ex. Similarly, the distributed data may be decoded by the clients or the streaming server ex, or the decoding processes may be shared between the clients and the streaming server ex. Furthermore, the data of the still images and video captured by not only the camera exbut also the camera exmay be transmitted to the streaming server exthrough the computer ex. The coding processes may be performed by the camera ex, the computer ex, or the streaming server ex, or shared among them.

500 111 500 111 114 500 114 Furthermore, the coding and decoding processes may be performed by an LSI exgenerally included in each of the computer exand the devices. The LSI exmay 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 exand others, and the coding and decoding processes may be performed using the software. Furthermore, when the cellular phone exis equipped with a camera, the video data obtained by the camera may be transmitted. The video data is data coded by the LSI exincluded in the cellular phone ex.

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

100 100 As described above, the clients may receive and reproduce the coded data in the content providing system ex. 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 ex, so that the user who does not have any particular right and equipment can implement personal broadcasting.

100 200 201 202 202 204 300 217 18 FIG. Aside from the example of the content providing system ex, at least one of the moving picture coding apparatus (image coding apparatus) and the moving picture decoding apparatus (image decoding apparatus) described in each of embodiments may be implemented in a digital broadcasting system exillustrated in. More specifically, a broadcast station excommunicates or transmits, via radio waves to a broadcast satellite ex, multiplexed data obtained by multiplexing audio data and others onto video data. The video data is data coded by the moving picture coding method described in each of embodiments (i.e., data coded by the image coding apparatus according to an aspect of the present disclosure). Upon receipt of the multiplexed data, the broadcast satellite extransmits radio waves for broadcasting. Then, a home-use antenna exwith a satellite broadcast reception function receives the radio waves. Next, a device such as a television (receiver) exand a set top box (STB) exdecodes the received multiplexed data, and reproduces the decoded data (i.e., functions as the image decoding apparatus according to an aspect of the present disclosure).

218 215 215 218 219 215 217 203 204 219 300 300 Furthermore, a reader/recorder ex(i) reads and decodes the multiplexed data recorded on a recording medium ex, such as a DVD and a BD, or (i) codes video signals in the recording medium ex, and in some cases, writes data obtained by multiplexing an audio signal on the coded data. The reader/recorder excan include the moving picture decoding apparatus or the moving picture coding apparatus as shown in each of embodiments. In this case, the reproduced video signals are displayed on the monitor ex, and can be reproduced by another device or system using the recording medium exon which the multiplexed data is recorded. It is also possible to implement the moving picture decoding apparatus in the set top box exconnected to the cable exfor a cable television or to the antenna exfor satellite and/or terrestrial broadcasting, so as to display the video signals on the monitor exof the television ex. The moving picture decoding apparatus may be implemented not in the set top box but in the television ex.

19 FIG. 300 300 301 204 203 302 303 306 illustrates the television (receiver) exthat uses the moving picture coding method and the moving picture decoding method described in each of embodiments. The television exincludes: a tuner exthat obtains or provides multiplexed data obtained by multiplexing audio data onto video data, through the antenna exor the cable ex, etc. that receives a broadcast; a modulation/demodulation unit exthat demodulates the received multiplexed data or modulates data into multiplexed data to be supplied outside; and a multiplexing/demultiplexing unit exthat demultiplexes the modulated multiplexed data into video data and audio data, or multiplexes video data and audio data coded by a signal processing unit exinto data.

300 306 304 305 309 307 308 300 317 312 300 310 300 311 312 317 313 218 314 216 315 316 216 300 The television exfurther includes: a signal processing unit exincluding an audio signal processing unit exand a video signal processing unit exthat decode audio data and video data and code audio data and video data, respectively (which function as the image coding apparatus and the image decoding apparatus according to the aspects of the present disclosure); and an output unit exincluding a speaker exthat provides the decoded audio signal, and a display unit exthat displays the decoded video signal, such as a display. Furthermore, the television exincludes an interface unit exincluding an operation input unit exthat receives an input of a user operation. Furthermore, the television exincludes a control unit exthat controls overall each constituent element of the television ex, and a power supply circuit unit exthat supplies power to each of the elements. Other than the operation input unit ex, the interface unit exmay include: a bridge exthat is connected to an external device, such as the reader/recorder ex; a slot unit exfor enabling attachment of the recording medium ex, such as an SD card; a driver exto be connected to an external recording medium, such as a hard disk; and a modem exto be connected to a telephone network. Here, the recording medium excan electrically record information using a non-volatile/volatile semiconductor memory element for storage. The constituent elements of the television exare connected to each other through a synchronous bus.

300 204 300 220 303 302 310 304 305 300 309 309 318 319 300 215 216 300 300 220 304 305 310 303 303 320 321 318 319 320 321 300 302 303 First, the configuration in which the television exdecodes multiplexed data obtained from outside through the antenna exand others and reproduces the decoded data will be described. In the television ex, upon a user operation through a remote controller exand others, the multiplexing/demultiplexing unit exdemultiplexes the multiplexed data demodulated by the modulation/demodulation unit ex, under control of the control unit exincluding a CPU. Furthermore, the audio signal processing unit exdecodes the demultiplexed audio data, and the video signal processing unit exdecodes the demultiplexed video data, using the decoding method described in each of embodiments, in the television ex. The output unit exprovides the decoded video signal and audio signal outside, respectively. When the output unit exprovides the video signal and the audio signal, the signals may be temporarily stored in buffers exand ex, and others so that the signals are reproduced in synchronization with each other. Furthermore, the television exmay read multiplexed data not through a broadcast and others but from the recording media exand ex, such as a magnetic disk, an optical disk, and a SD card. Next, a configuration in which the television excodes 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 ex, upon a user operation through the remote controller exand others, the audio signal processing unit excodes an audio signal, and the video signal processing unit excodes a video signal, under control of the control unit exusing the coding method described in each of embodiments. The multiplexing/demultiplexing unit exmultiplexes the coded video signal and audio signal, and provides the resulting signal outside. When the multiplexing/demultiplexing unit exmultiplexes the video signal and the audio signal, the signals may be temporarily stored in the buffers exand ex, and others so that the signals are reproduced in synchronization with each other. Here, the buffers ex, ex, ex, and exmay be plural as illustrated, or at least one buffer may be shared in the television ex. Furthermore, data may be stored in a buffer so that the system overflow and underflow may be avoided between the modulation/demodulation unit exand the multiplexing/demultiplexing unit ex, for example.

300 300 Furthermore, the television exmay 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 excan 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.

218 300 218 300 218 Furthermore, when the reader/recorder exreads or writes multiplexed data from or on a recording medium, one of the television exand the reader/recorder exmay decode or code the multiplexed data, and the television exand the reader/recorder exmay share the decoding or coding.

20 FIG. 400 400 401 402 403 404 405 406 407 401 215 215 402 401 403 401 215 404 215 215 405 215 406 401 405 407 400 407 404 402 403 406 401 407 As an example,illustrates a configuration of an information reproducing/recording unit exwhen data is read or written from or on an optical disk. The information reproducing/recording unit exincludes constituent elements ex, ex, ex, ex, ex, ex, and exto be described hereinafter. The optical head exirradiates a laser spot in a recording surface of the recording medium exthat is an optical disk to write information, and detects reflected light from the recording surface of the recording medium exto read the information. The modulation recording unit exelectrically drives a semiconductor laser included in the optical head ex, and modulates the laser light according to recorded data. The reproduction demodulating unit examplifies a reproduction signal obtained by electrically detecting the reflected light from the recording surface using a photo detector included in the optical head ex, and demodulates the reproduction signal by separating a signal component recorded on the recording medium exto reproduce the necessary information. The buffer extemporarily holds the information to be recorded on the recording medium exand the information reproduced from the recording medium ex. The disk motor exrotates the recording medium ex. The servo control unit exmoves the optical head exto a predetermined information track while controlling the rotation drive of the disk motor exso as to follow the laser spot. The system control unit excontrols overall the information reproducing/recording unit ex. The reading and writing processes can be implemented by the system control unit exusing various information stored in the buffer exand generating and adding new information as necessary, and by the modulation recording unit ex, the reproduction demodulating unit ex, and the servo control unit exthat record and reproduce information through the optical head exwhile being operated in a coordinated manner. The system control unit exincludes, for example, a microprocessor, and executes processing by causing a computer to execute a program for read and write.

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

21 FIG. 215 215 230 231 230 215 233 232 234 233 232 234 233 400 233 215 illustrates the recording medium exthat is the optical disk. On the recording surface of the recording medium ex, guide grooves are spirally formed, and an information track exrecords, 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 exthat are a unit for recording data. Reproducing the information track exand 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 exincludes a data recording area ex, an inner circumference area ex, and an outer circumference area ex. The data recording area exis an area for use in recording the user data. The inner circumference area exand the outer circumference area exthat are inside and outside of the data recording area ex, respectively are for specific use except for recording the user data. The information reproducing/recording unitreads 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 exof the recording medium ex.

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.

210 205 202 211 210 200 211 111 114 19 FIG. Furthermore, a car exhaving an antenna excan receive data from the satellite exand others, and reproduce video on a display device such as a car navigation system exset in the car ex, in the digital broadcasting system ex. Here, a configuration of the car navigation system exwill be a configuration, for example, including a GPS receiving unit from the configuration illustrated in. The same will be true for the configuration of the computer ex, the cellular phone ex, and others.

22 FIG.A 114 114 350 110 365 358 365 350 114 366 357 356 367 364 367 illustrates the cellular phone exthat uses the moving picture coding method and the moving picture decoding method described in embodiments. The cellular phone exincludes: an antenna exfor transmitting and receiving radio waves through the base station ex; a camera unit excapable of capturing moving and still images; and a display unit exsuch as a liquid crystal display for displaying the data such as decoded video captured by the camera unit exor received by the antenna ex. The cellular phone exfurther includes: a main body unit including an operation key unit ex; an audio output unit exsuch as a speaker for output of audio; an audio input unit exsuch as a microphone for input of audio; a memory unit exfor 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 exthat is an interface unit for a recording medium that stores data in the same manner as the memory unit ex.

114 114 360 358 366 370 361 362 355 363 359 352 353 354 364 367 22 FIG.B Next, an example of a configuration of the cellular phone exwill be described with reference to. In the cellular phone ex, a main control unit exdesigned to control overall each unit of the main body including the display unit exas well as the operation key unit exis connected mutually, via a synchronous bus ex, to a power supply circuit unit ex, an operation input control unit ex, a video signal processing unit ex, a camera interface unit ex, a liquid crystal display (LCD) control unit ex, a modulation/demodulation unit ex, a multiplexing/demultiplexing unit ex, an audio signal processing unit ex, the slot unit ex, and the memory unit ex.

361 114 When a call-end key or a power key is turned ON by a user's operation, the power supply circuit unit exsupplies the respective units with power from a battery pack so as to activate the cell phone ex.

114 354 356 360 352 351 350 114 351 350 352 354 357 In the cellular phone ex, the audio signal processing unit exconverts the audio signals collected by the audio input unit exin voice conversation mode into digital audio signals under the control of the main control unit exincluding a CPU, ROM, and RAM. Then, the modulation/demodulation unit experforms spread spectrum processing on the digital audio signals, and the transmitting and receiving unit experforms digital-to-analog conversion and frequency conversion on the data, so as to transmit the resulting data via the antenna ex. Also, in the cellular phone ex, the transmitting and receiving unit examplifies the data received by the antenna exin voice conversation mode and performs frequency conversion and the analog-to-digital conversion on the data. Then, the modulation/demodulation unit experforms inverse spread spectrum processing on the data, and the audio signal processing unit exconverts it into analog audio signals, so as to output them via the audio output unit ex.

366 360 362 360 352 351 110 350 358 Furthermore, when an e-mail in data communication mode is transmitted, text data of the e-mail inputted by operating the operation key unit exand others of the main body is sent out to the main control unit exvia the operation input control unit ex. The main control unit excauses the modulation/demodulation unit exto perform spread spectrum processing on the text data, and the transmitting and receiving unit experforms the digital-to-analog conversion and the frequency conversion on the resulting data to transmit the data to the base station exvia the antenna ex. 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 ex.

355 365 353 365 354 356 353 When video, still images, or video and audio in data communication mode is or are transmitted, the video signal processing unit excompresses and codes video signals supplied from the camera unit exusing the moving picture coding method shown in each of embodiments (i.e., functions as the image coding apparatus according to the aspect of the present disclosure), and transmits the coded video data to the multiplexing/demultiplexing unit ex. In contrast, during when the camera unit excaptures video, still images, and others, the audio signal processing unit excodes audio signals collected by the audio input unit ex, and transmits the coded audio data to the multiplexing/demultiplexing unit ex.

353 355 354 352 351 350 The multiplexing/demultiplexing unit exmultiplexes the coded video data supplied from the video signal processing unit exand the coded audio data supplied from the audio signal processing unit ex, using a predetermined method. Then, the modulation/demodulation unit (modulation/demodulation circuit unit) experforms spread spectrum processing on the multiplexed data, and the transmitting and receiving unit experforms digital-to-analog conversion and frequency conversion on the data so as to transmit the resulting data via the antenna ex.

350 353 355 354 370 355 358 359 354 357 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 ex, the multiplexing/demultiplexing unit exdemultiplexes the multiplexed data into a video data bit stream and an audio data bit stream, and supplies the video signal processing unit exwith the coded video data and the audio signal processing unit exwith the coded audio data, through the synchronous bus ex. The video signal processing unit exdecodes the video signal using a moving picture decoding method corresponding to the moving picture coding method shown in each of embodiments (i.e., functions as the image decoding apparatus according to the aspect of the present disclosure), and then the display unit exdisplays, for instance, the video and still images included in the video file linked to the Web page via the LCD control unit ex. Furthermore, the audio signal processing unit exdecodes the audio signal, and the audio output unit exprovides the audio.

300 114 200 Furthermore, similarly to the television ex, a terminal such as the cellular phone exprobably 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 exreceives 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 moving picture coding method and the moving picture 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 disclosure is not limited to embodiments, and various modifications and revisions are possible without departing from the scope of the present disclosure.

Video data can be generated by switching, as necessary, between (i) the moving picture coding method or the moving picture coding apparatus shown in each of embodiments and (ii) a moving picture coding method or a moving picture coding apparatus in conformity with a different standard, such as MPEG-2, MPEG-4 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 conforms 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 moving picture coding method and by the moving picture coding apparatus shown in each of embodiments will be hereinafter described. The multiplexed data is a digital stream in the MPEG-2 Transport Stream format.

23 FIG. 23 FIG. illustrates a structure of the multiplexed data. As illustrated in, 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 moving picture coding method or by the moving picture coding apparatus shown in each of embodiments, or in a moving picture coding method or by a moving picture coding apparatus in conformity with a conventional standard, such as MPEG-2, MPEG-4 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 audio to be mixed with the primary audio.

24 FIG. 235 238 236 239 237 240 241 244 242 245 243 246 247 schematically illustrates how data is multiplexed. First, a video stream excomposed of video frames and an audio stream excomposed of audio frames are transformed into a stream of PES packets exand a stream of PES packets ex, and further into TS packets exand TS packets ex, respectively. Similarly, data of a presentation graphics stream exand data of an interactive graphics stream exare transformed into a stream of PES packets exand a stream of PES packets ex, and further into TS packets exand TS packets ex, respectively. These TS packets are multiplexed into a stream to obtain multiplexed data ex.

25 FIG. 25 FIG. 25 FIG. 1 2 3 4 illustrates how a video stream is stored in a stream of PES packets in more detail. The first bar inshows a video frame stream in a video stream. The second bar shows the stream of PES packets. As indicated by arrows denoted as yy, yy, yy, and yyin, 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.

26 FIG. 26 FIG. 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. 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.

27 FIG. 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.

28 FIG. Each of the multiplexed data information files is management information of the multiplexed data as shown in. 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.

28 FIG. As illustrated in, the multiplexed data information 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.

29 FIG. As shown in, 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 the present embodiment, 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 moving picture coding method or the moving picture coding apparatus described in each of embodiments includes a step or a unit for allocating unique information indicating video data generated by the moving picture coding method or the moving picture 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 moving picture coding method or the moving picture coding apparatus described in each of embodiments can be distinguished from video data that conforms to another standard.

30 FIG. 100 101 102 103 Furthermore,illustrates steps of the moving picture decoding method according to the present embodiment. In Step exS, the stream type included in the PMT or the video stream attribute information included in the multiplexed data information is obtained from the multiplexed data. Next, in Step exS, it is determined whether or not the stream type or the video stream attribute information indicates that the multiplexed data is generated by the moving picture coding method or the moving picture 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 moving picture coding method or the moving picture coding apparatus in each of embodiments, in Step exS, decoding is performed by the moving picture 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, MPEG-4 AVC, and VC-1, in Step exS, decoding is performed by a moving picture 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 moving picture decoding method or the moving picture decoding apparatus that is described in each of embodiments can perform decoding. Even when multiplexed data that conforms to a different standard is input, an appropriate decoding method or apparatus can be selected. Thus, it becomes possible to decode information without any error. Furthermore, the moving picture coding method or apparatus, or the moving picture decoding method or apparatus in the present embodiment can be used in the devices and systems described above.

31 FIG. 500 500 501 502 503 504 505 506 507 508 509 510 505 505 Each of the moving picture coding method, the moving picture coding apparatus, the moving picture decoding method, and the moving picture 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,illustrates a configuration of the LSI exthat is made into one chip. The LSI exincludes elements ex, ex, ex, ex, ex, ex, ex, ex, and exto be described below, and the elements are connected to each other through a bus ex. The power supply circuit unit exis activated by supplying each of the elements with power when the power supply circuit unit exis turned on.

500 117 113 509 501 502 503 504 512 511 501 507 507 507 506 107 215 508 For example, when coding is performed, the LSI exreceives an AV signal from a microphone ex, a camera ex, and others through an AV IO exunder control of a control unit exincluding a CPU ex, a memory controller ex, a stream controller ex, and a driving frequency control unit ex. The received AV signal is temporarily stored in an external memory ex, such as an SDRAM. Under control of the control unit ex, the stored data is segmented into data portions according to the processing amount and speed to be transmitted to a signal processing unit ex. Then, the signal processing unit excodes 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 exsometimes multiplexes the coded audio data and the coded video data, and a stream IO exprovides the multiplexed data outside. The provided multiplexed data is transmitted to the base station ex, or written on the recording medium ex. When data sets are multiplexed, the data should be temporarily stored in the buffer exso that the data sets are synchronized with each other.

511 500 500 508 500 Although the memory exis an element outside the LSI ex, it may be included in the LSI ex. The buffer exis not limited to one buffer, but may be composed of buffers. Furthermore, the LSI exmay be made into one chip or a plurality of chips.

501 502 503 504 512 501 507 507 502 507 501 507 502 507 Furthermore, although the control unit exincludes the CPU ex, the memory controller ex, the stream controller ex, the driving frequency control unit ex, the configuration of the control unit exis not limited to such. For example, the signal processing unit exmay further include a CPU. Inclusion of another CPU in the signal processing unit excan improve the processing speed. Furthermore, as another example, the CPU exmay serve as or be a part of the signal processing unit ex, and, for example, may include an audio signal processing unit. In such a case, the control unit exincludes the signal processing unit exor the CPU exincluding a part of the signal processing unit ex.

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 disclosure is applied to biotechnology.

500 502 When video data generated in the moving picture coding method or by the moving picture coding apparatus described in each of embodiments is decoded, compared to when video data that conforms to a conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1 is decoded, the processing amount probably increases. Thus, the LSI exneeds to be set to a driving frequency higher than that of the CPU exto 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.

300 500 800 803 803 801 803 803 802 32 FIG. In order to solve the problem, the moving picture decoding apparatus, such as the television exand the LSI exis configured to determine to which standard the video data conforms, and switch between the driving frequencies according to the determined standard.illustrates a configuration exin the present embodiment. A driving frequency switching unit exsets a driving frequency to a higher driving frequency when video data is generated by the moving picture coding method or the moving picture coding apparatus described in each of embodiments. Then, the driving frequency switching unit exinstructs a decoding processing unit exthat executes the moving picture 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 exsets a driving frequency to a lower driving frequency than that of the video data generated by the moving picture coding method or the moving picture coding apparatus described in each of embodiments. Then, the driving frequency switching unit exinstructs the decoding processing unit exthat conforms to the conventional standard to decode the video data.

803 502 512 801 802 507 502 512 502 507 502 502 508 502 31 FIG. 31 FIG. 34 FIG. More specifically, the driving frequency switching unit exincludes the CPU exand the driving frequency control unit exin. Here, each of the decoding processing unit exthat executes the moving picture decoding method described in each of embodiments and the decoding processing unit exthat conforms to the conventional standard corresponds to the signal processing unit exin. The CPU exdetermines to which standard the video data conforms. Then, the driving frequency control unit exdetermines a driving frequency based on a signal from the CPU ex. Furthermore, the signal processing unit exdecodes the video data based on the signal from the CPU ex. For example, the identification information described in Embodiment 4 is probably used for identifying the video data. The identification information is not limited to the one described in Embodiment 4 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 exselects 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. The driving frequency can be selected by storing the look-up table in the buffer exand in an internal memory of an LSI, and with reference to the look-up table by the CPU ex.

33 FIG. 200 507 201 502 202 502 512 512 203 502 512 512 illustrates steps for executing a method in the present embodiment. First, in Step exS, the signal processing unit exobtains identification information from the multiplexed data. Next, in Step exS, the CPU exdetermines 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 moving picture coding method and the moving picture coding apparatus described in each of embodiments, in Step exS, the CPU extransmits a signal for setting the driving frequency to a higher driving frequency to the driving frequency control unit ex. Then, the driving frequency control unit exsets 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, MPEG-4 AVC, and VC-1, in Step exS, the CPU extransmits a signal for setting the driving frequency to a lower driving frequency to the driving frequency control unit ex. Then, the driving frequency control unit exsets the driving frequency to the lower driving frequency than that in the case where the video data is generated by the moving picture coding method and the moving picture coding apparatus described in each of embodiment.

500 500 500 500 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 exor an apparatus including the LSI ex. For example, when the driving frequency is set lower, the voltage to be applied to the LSI exor the apparatus including the LSI exis 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 MPEG-4 AVC is larger than the processing amount for decoding video data generated by the moving picture coding method and the moving picture coding apparatus described in each of embodiments, the driving frequency is probably set in reverse order to the setting described above.

500 500 500 500 502 502 502 502 502 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 moving picture coding method and the moving picture coding apparatus described in each of embodiments, the voltage to be applied to the LSI exor the apparatus including the LSI exis probably set higher. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the voltage to be applied to the LSI exor the apparatus including the LSI exis probably set lower. As another example, when the identification information indicates that the video data is generated by the moving picture coding method and the moving picture coding apparatus described in each of embodiments, the driving of the CPU exdoes not probably have to be suspended. When the identification information indicates that the video data conforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1, the driving of the CPU exis probably suspended at a given time because the CPU exhas extra processing capacity. Even when the identification information indicates that the video data is generated by the moving picture coding method and the moving picture coding apparatus described in each of embodiments, in the case where the CPU exhas extra processing capacity, the driving of the CPU exis 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, MPEG-4 AVC, and VC-1.

500 500 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 exor the apparatus including the LSI exis driven using a battery, the battery life can be extended with the power conservation effect.

507 500 500 507 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 cellular phone. In order to enable decoding the plurality of video data that conforms to the different standards, the signal processing unit exof the LSI exneeds to conform to the different standards. However, the problems of increase in the scale of the circuit of the LSI exand increase in the cost arise with the individual use of the signal processing units exthat conform to the respective standards.

900 902 901 901 35 FIG.A In order to solve the problem, what is conceived is a configuration in which the decoding processing unit for implementing the moving picture decoding method described in each of embodiments and the decoding processing unit that conforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Exinshows an example of the configuration. For example, the moving picture decoding method described in each of embodiments and the moving picture decoding method that conforms to MPEG-4 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 include use of a decoding processing unit exthat conforms to MPEG-4 AVC. In contrast, a dedicated decoding processing unit exis probably used for other processing unique to an aspect of the present disclosure. Since the aspect of the present disclosure is characterized by entropy decoding in particular, for example, the dedicated decoding processing unit exis used for entropy decoding. Otherwise, the decoding processing unit is probably shared for one of deblocking filtering, motion compensation, and inverse quantization or all of the processing. The decoding processing unit for implementing the moving picture 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 MPEG-4 AVC.

1000 1001 1002 1003 1001 1002 500 35 FIG.B Furthermore, exinshows another example in that processing is partly shared. This example uses a configuration including a dedicated decoding processing unit exthat supports the processing unique to an aspect of the present disclosure, a dedicated decoding processing unit exthat supports the processing unique to another conventional standard, and a decoding processing unit exthat supports processing to be shared between the moving picture decoding method according to the aspect of the present disclosure and the conventional moving picture decoding method. Here, the dedicated decoding processing units exand exare not necessarily specialized for the processing according to the aspect of the present disclosure and the processing of the conventional standard, respectively, and may be the ones capable of implementing general processing. Furthermore, the configuration of the present embodiment can be implemented by the LSI ex.

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 moving picture decoding method according to the aspect of the present disclosure and the moving picture decoding method in conformity with the conventional standard.

The image coding apparatus and the image decoding apparatus according to an aspect of the present disclosure are applicable to television receivers, digital video recorders, car navigation systems, mobile phones, digital cameras, or digital video cameras, for example.