Moving image encoding method, moving image decoding method, and data recording medium

• US 20040190615A1
• Filed: 01/15/2004
• Published: 09/30/2004
• Est. Priority Date: 05/22/2002
• Status: Abandoned Application

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Abe, Kiyofumi, Kadono, Shinya, Kondo, Satoshi, Hagai, Makoto
• Application Number:
  US10/483,813
• Publication Number:
  US 20040190615A1
• Time in Patent Office: Days
• US Class Current: 375/240.15
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• CPC Class Codes: H04N 19/56 Motion estimation with initialisation of the vector search, e.g. estimating a good candidate to initiate a search
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• CPC Class Codes: H04N 19/93 Run-length coding

Abstract

A method for realizing a direct mode without reference to temporally subsequent pictures but with reference to motion vectors of coded blocks in one picture including a current block is suggested for performing predictive coding on the current block using the direct mode under the environment where such temporally subsequent pictures are not available for reference, and further, high coding efficiency is achieved even in a case of motion compensation with only forward reference by eliminating items concerning reference to the subsequent pictures from a table of coding modes and thus reducing the number of items in the table.

Claims

1. A moving picture coding method for coding a moving picture to generate a coded stream, comprising a coding step of allowing use of a direct mode for coding a B-picture which is predictively coded with reference to a plurality of temporally preceding or subsequent coded pictures, the direct mode being a mode for performing motion compensation of a current block to be coded with reference to motion vectors of coded blocks,

wherein the coding step includes a motion compensation step of performing motion compensation, as in the direct mode, with reference to the motion vectors of the coded blocks located around the current block to be coded in one picture, when the B-picture is predictively coded with reference only to the coded pictures located in one direction, in display order, of the picture including the current block to be coded.

2. The moving picture coding method according to claim 1,

wherein in the motion compensation step, the motion compensation is performed when all the coded pictures which are referred to for performing the predictive coding are pictures that temporally precede the picture including the current block to be coded.

3. The moving picture coding method according to claim 1,

wherein in the motion compensation step, the motion compensation is performed when none of the coded pictures are available for reference for performing the predictive coding, said coded pictures being temporally subsequent to the picture including the current block to be coded.

4. The moving picture coding method according to claim 1,

wherein the motion compensation step includes a motion vector calculation step of calculating a motion vector of the current block to be coded, by referring to one or more motion vectors of the coded blocks, said motion vectors referring to one or more of the plurality of pictures in order of temporal proximity to the picture including the current block to be coded, and by calculating a median or an average of said motion vectors, when the motion compensation is performed, and

in the motion compensation step, the motion compensation is performed in direct mode using said one or more motion vectors obtained in the motion vector calculation step.

5. The moving picture coding method according to claim 4,

wherein in the motion vector calculation step, the motion vector is calculated with reference to motion vectors of the coded blocks, said motion vectors referring to one or more of the plurality of pictures in order of proximity in display order to the picture including the current block to be coded.

6. The moving picture coding method according to claim 1,

wherein in the motion compensation step, the motion compensation is performed with reference to one or more of the pictures in order of temporal proximity by considering a value of a motion vector of the current block to be coded as “

0”

in one of the following cases, when the motion compensation is performed;

any of the coded blocks are located outside the picture or a slice including the current block to be coded;

values of any of the motion vectors of the coded blocks are “

0”

; and

any of the coded blocks have no motion vector.

8. The moving picture coding method according to claim 1,

wherein the coding step includes a table regeneration step of regenerating a table by eliminating a predictive coding method for backward reference from a table in which predictive coding methods for the B-picture are associated with identifiers for identifying the predictive coding methods, and

in the coding step, an identifier indicating a predictive coding method for the B-picture is coded using the regenerated table.

19. A data recording medium for storing a program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 1.

20. A program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 1.

21. A coded data stream that contains header portions and data portions which are arranged alternately for each of slices that make up a picture,

wherein when a B-picture is predictively coded in direct mode with reference only to coded pictures located in temporally one direction of a picture including a current block to be coded, said B-picture being predictively coded with reference to a plurality of temporally preceding or subsequent coded pictures, one of the following flags is placed in the header portion of each slice:

a flag indicating that motion compensation is performed with reference to motion vectors of a plurality of coded blocks located around the current block to be coded in one picture; and

a flag indicating that motion compensation is performed by considering a value of a motion vector of the current block to be coded as “

0”

, and

coded moving picture data obtained by the moving picture coding method according to claim 1 is placed in the data portion of said each slice.

7. A moving picture coding method for coding a moving picture to generate a coded stream, comprising a coding step of allowing use of a direct mode for coding a B-picture which is predictively coded with reference to a plurality of temporally preceding or subsequent coded pictures, the direct mode being a mode for performing motion compensation of a current block to be coded with reference to motion vectors of coded blocks,

wherein in the coding step, motion compensation is performed, as in the direct mode, with reference to one or more of the plurality of the pictures in order of temporal proximity by considering a value of a motion vector of the current block to be coded as “

0”

, when the B-picture is predictively coded with reference only to the coded pictures located in one direction, in display order, of a picture including the current block to be coded.

22. The moving picture coding method according to claim 7,

wherein the coding step includes a table regeneration step of regenerating a table by eliminating a predictive coding method for backward reference from a table in which predictive coding methods for the B-picture are associated with identifiers for identifying the predictive coding methods, and

in the coding step, an identifier indicating a predictive coding method for the B-picture is coded using the regenerated table.

24. A data recording medium for storing a program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 7.

27. A program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 7.

30. A coded data stream that contains header portions and data portions which are arranged alternately for each of slices that make up a picture,

wherein when a B-picture is predictively coded in direct mode with reference only to coded pictures located in temporally one direction of a picture including a current block to be coded, said B-picture being predictively coded with reference to a plurality of temporally preceding or subsequent coded pictures, one of the following flags is placed in the header portion of each slice:

a flag indicating that motion compensation is performed with reference to motion vectors of a plurality of coded blocks located around the current block to be coded in one picture; and

a flag indicating that motion compensation is performed by considering a value of a motion vector of the current block to be coded as “

0”

, and

coded moving picture data obtained by the moving picture coding method according to claim 7 is placed in the data portion of said each slice.

9. A moving picture decoding method for decoding a coded stream obtained by coding a moving picture, comprising a decoding step of allowing use of a direct mode for decoding a B-picture which is predictively decoded with reference to a plurality of temporally preceding or subsequent decoded pictures, the direct mode being a mode for performing motion compensation of a current block to be decoded with reference to motion vectors of decoded blocks,

wherein the decoding step includes a motion compensation step of performing motion compensation, as in the direct mode, with reference to the motion vectors of the decoded blocks located around the current block to be decoded in one picture, when the B-picture is predictively decoded with reference only to the decoded pictures located in temporally one direction of said picture including the current block to be decoded.

10. The moving picture decoding method according to claim 9, wherein in the motion compensation step, the motion compensation is performed when all the decoded pictures which are referred to for performing the predictive decoding are pictures that temporally precede the picture including the current block to be decoded.

11. The moving picture decoding method according to claim 9, wherein in the motion compensation step, the motion compensation is performed when none of the decoded pictures are available for reference for performing the predictive decoding, said decoded pictures being temporally subsequent to the picture including the current block to be decoded.

12. The moving picture decoding method according to claim 9,

wherein the motion compensation step includes a motion vector calculation step of calculating a motion vector of the current block to be decoded, by referring to one or more motion vectors of the decoded blocks, said motion vectors referring to one or more of the plurality of pictures in order of temporal proximity to the picture including the current block to be decoded, and by calculating a median or an average of said motion vectors, when the motion compensation is performed, and

in the motion compensation step, the motion compensation is performed in direct mode using said one or more motion vectors obtained in the motion vector calculation step.

13. The moving picture decoding method according to claim 12,

wherein in the motion vector calculation step, the motion vector is calculated with reference to motion vectors of the decoded blocks, said motion vectors referring to one or more of the plurality of pictures in order of proximity in display order to the picture including the current block to be decoded.

14. The moving picture decoding method according to claim 9,

wherein in the motion compensation step, the motion compensation is performed with reference to one or more of the pictures in order of temporal proximity by considering a value of a motion vector of the current block to be decoded as “

0”

in one of the following cases, when the motion compensation is performed;

any of the decoded blocks are located outside the picture or a slice including the current block to be decoded;

values of any of the motion vectors of the decoded blocks are “

0”

; and

any of the decoded blocks have no motion vector.

16. The moving picture decoding method according to claim 9,

wherein the decoding step includes a table regeneration step of regenerating a table by eliminating a predictive decoding method for backward reference from a table in which predictive decoding methods for the B-picture are associated with identifiers for identifying the predictive decoding methods, and

in the decoding step, an identifier for identifying a predictive decoding method for the B-picture in the coded stream is decoded, the predictive decoding method for said B-picture is identified using the regenerated table, and the current block to be decoded is predictively decoded according to the identified predictive decoding method.

25. A data recording medium for storing a program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 9.

28. A program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 9.

15. A moving picture decoding method for decoding a coded stream obtained by coding a moving picture, comprising a decoding step of allowing use of a direct mode for decoding a B-picture which is predictively decoded with reference to a plurality of temporally preceding or subsequent decoded pictures, the direct mode being a mode for performing motion compensation of a current block to be decoded with reference to motion vectors of decoded blocks,

wherein in the decoding step, motion compensation is performed, as in the direct mode, with reference to one or more of the plurality of the pictures in order of temporal proximity by considering a value of a motion vector of the current block to be decoded as “

0”

, when the B-picture is predictively coded with reference only to the decoded pictures located in temporally one direction of a picture including the current block to be decoded.

23. The moving picture decoding method according to claim 15,

wherein the decoding step includes a table regeneration step of regenerating a table by eliminating a predictive decoding method for backward reference from a table in which predictive decoding methods for the B-picture are associated with identifiers for identifying the predictive decoding methods, and

in the decoding step, an identifier for identifying a predictive decoding method for the B-picture in the coded stream is decoded, the predictive decoding method for said B-picture is identified using the regenerated table, and the current block to be decoded is predictively decoded according to the identified predictive decoding method.

26. A data recording medium for storing a program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 15.

29. A program for causing a computer to execute each of the steps included in either the moving picture coding method or the moving picture decoding method according to claim 15.

17. A moving picture coding apparatus for coding a moving picture to generate a coded stream, comprising a coding unit operable to allow use of a direct mode for coding a B-picture which is predictively coded with reference to a plurality of temporally preceding or subsequent coded pictures, the direct mode being a mode for performing motion compensation of a current block to be coded with reference to motion vectors of coded blocks,

wherein the coding unit includes a motion compensation unit operable to perform motion compensation, as in the direct mode, with reference to the motion vectors of the coded blocks located around the current block to be coded in one picture, when the B-picture is predictively coded with reference only to the coded pictures located in temporally one direction of the picture including the current block to be coded.

18. A moving picture decoding apparatus for decoding a coded stream obtained by coding a moving picture, comprising a decoding unit operable to allow use of a direct mode for decoding a B-picture which is predictively decoded with reference to a plurality of temporally preceding or subsequent decoded pictures, the direct mode being a mode for performing motion compensation of a current block to be decoded with reference to motion vectors of decoded blocks,

wherein the decoding unit includes a motion compensation unit operable to perform motion compensation, as in the direct mode, with reference to the motion vectors of the decoded blocks located around the current block to be decoded in one picture, when the B-picture is predictively decoded with reference only to the decoded pictures located in temporally one direction of the picture including the current block to be decoded.