Method and apparatus for generating/evaluating in a picture signal encoding/decoding one or more prediction information items

• US 20050157797A1
• Filed: 01/14/2005
• Published: 07/21/2005
• Est. Priority Date: 01/21/2004
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Gaedke, Klaus
• Granted Patent: US 8,107,532 B2
• Time in Patent Office: Days
• US Class Current: 375/240.240
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• 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 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

Advanced Video Coding uses intra prediction for 4*4 pixel blocks whereby reconstructed samples from adjacent pixel blocks are used to predict a current block. Nine different intra prediction modes are available in AVC. In order to save bits for signalling the prediction modes, a flag and a 3-bit parameter are used. If this flag is set the most probable prediction mode, which is calculated from previous predictions, is used by the encoder and the decoder to reconstruct the actual prediction mode. If the flag is cleared, the 3-bit parameter is sent to select the prediction mode independently. According to the invention, the flag is applied more frequently, based on a prediction error threshold, instead of applying the optimum prediction mode for a current pixel block.

Claims

1. Method for generating in a picture signal encoding one or more prediction information items required in a decoding of the encoded picture signal for the prediction of a current pixel block, said method including the steps:

either providing a first value for a prediction information item said first value indicating to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previuosly predicted pixel blocks that are adjacent to said current pixel block, wherein said prediction information item first value has a first word length and is for example a flag,

or providing a second value for said prediction information item said second value indicating not to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, and providing the actual prediction mode value for said current pixel block, said actual prediction mode being related to the minimum prediction error for said current pixel block, wherein said actual prediction mode value has a second word length that is greater than said first word length,

wherein said first value is provided for said prediction information item and not an actual prediction mode value for said current pixel block if, when applying said first value for said prediction information item instead of applying a minimum prediction error related one of the available actual prediction modes, the actual prediction error for said current pixel block is greater than when applying said minimum prediction error related prediction mode but is smaller or equal a predetermined prediction error threshold value.

2. Method according to claim 1, wherein said encoding or said decoding is of type AVC and said prediction is a 4*4 intra prediction for luminance and/or chrominance blocks.

3. Method according to claim 1, wherein said previously predicted pixel blocks that are adjacent to said current pixel block are the blocks to the left and on top of the current pixel block,

or are the blocks to the left, to the top left and on top of the current pixel block.

4. Method according to claim 1, wherein said threshold is changed adaptively according to the current type of picture content.

5. Method according to claim 1, wherein the level of said threshold is selected such that the prediction error that is related to said threshold is about 10-15% greater than the minimum possible prediction error that arises when applying a corresponding one of the actually available prediction modes.

6. Method for intra predicting in a picture signal decoding a current pixel block by evaluating one or more received prediction information items required for the prediction of said current pixel block, said method including the steps:

either evaluating a received first value for a prediction information item said first value indicating to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, wherein said prediction information item first value has a first word length and is for example a flag,

or evaluating a second received value for said prediction information item said second value indicating not to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, and evaluating a received actual prediction mode value for said current pixel block, said actual prediction mode being related to the minimum prediction error for said current pixel block, wherein said actual prediction mode value has a second word length that is greater than said first word length,

wherein said received first value is applied for said prediction information item for an intra prediction of said current pixel block if, when applying said first value for said prediction information item instead of applyling a minimum prediction error related one of the available actual prediction modes, the actual intra prediction error for said current pixel block would be greater than when applying said minimum prediction error related prediction mode but is smaller or equal a predetermined intra prediction error threshold value.

7. Method according to claim 6, wherein said encoding or said decoding is of type AVC and said prediction is a 4*4 intra prediction for luminance and/or chrominance blocks.

8. Method according to claim 6, wherein said previously predicted pixel blocks that are adjacent to said current pixel block are the blocks to the left and on top of the current pixel block,

or are the blocks to the left, to the top left and on top of the current pixel block.

9. Method according to claim 6, wherein said threshold is changed adaptively according to the current type of picture content.

10. Method according to claim 6, wherein the level of said threshold is selected such that the prediction error that is related to said threshold is about 10-15% greater than the minimum possible prediction error that arises when applying a corresponding one of the actually available prediction modes.

11. Apparatus for generating in a picture signal encoding one or more prediction information items required in a decoding of the encoded picture signal for the prediction of a current pixel block, said apparatus including means being adapted for:

either providing a first value for a prediction information item said first value indicating to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, wherein said prediction information item first value has a first word length and is for example a flag,

or providing a second value for said prediction information item said second value indicating not to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, and providing the actual prediction mode value for said current pixel block, said actual prediction mode being related to the minimum prediction error for said current pixel block, wherein said actual prediction mode value has a second word length that is greater than said first word length,

wherein said means are being adapted for providing said first value for said prediction information item and not providing an actual prediction mode value for said current pixel block if, when applying said first value for said prediction information item instead of applying a minimum prediction error related one of the available actual prediction modes, the actual prediction error for said current pixel block is greater than when applying said minimum prediction error related prediction mode but is smaller or equal a predetermined prediction error threshold value.

12. Apparatus according to claim 11, wherein said encoding or said decoding is of type AVC and said prediction is a 4*4 intra prediction for luminance and/or chrominance blocks.

13. Apparatus according to claim 11, wherein said previously predicted pixel blocks that are adjacent to said current pixel block are the blocks to the left and on top of the current pixel block,

or are the blocks to the left, to the top left and on top of the current pixel block.

14. Apparatus according to claim 11, wherein said threshold is changed adaptively according to the current type of picture content.

15. Apparatus according to claim 11, wherein the level of said threshold is selected such that the prediction error that is related to said threshold is about 10-15% greater than the minimum possible prediction error that arises when applying a corresponding one of the actually available prediction modes.

16. Apparatus for intra predicting in a picture signal decoding a current pixel block by evaluating one or more received prediction information items required for the prediction of said current pixel block, said apparatus including means being adapted for:

either evaluating a received first value for a prediction information item said first value indicating to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, wherein said prediction information item first value has a first word length and is for example a flag,

or evaluating a second received value for said prediction information item said second value indicating not to use for a current pixel block a prediction mode that is to be derived from one or more prediction modes of one or more previously predicted pixel blocks that are adjacent to said current pixel block, and evaluating a received actual prediction mode value for said current pixel block, said actual prediction mode being related to the minimum prediction error for said current pixel block, wherein said actual prediction mode value has a second word length that is greater than said first word length,

wherein said means are being adapted for applying said received first value for said prediction information item for an intra prediction of said current pixel block if, when applying said first value for said prediction information item instead of applying a minimum prediction error related one of the available actual prediction modes, the actual intra prediction error for said current pixel block would be greater than when applying said minimum prediction error related prediction mode but is smaller or equal a predetermined intra prediction error threshold value.

17. Apparatus according to claims 16, wherein said encoding or said decoding is of type AVC and said prediction is a 4*4 intra prediction for luminance and/or chrominance blocks.

18. Apparatus according to claims 16, wherein said previously predicted pixel blocks that are adjacent to said current pixel block are the blocks to the left and on top of the current pixel block,

or are the blocks to the left, to the top left and on top of the current pixel block.

19. Apparatus according to claim 16, wherein said threshold is changed adaptively according to the current type of picture content.

20. Apparatus according to claim 16, wherein the level of said threshold is selected such that the prediction error that is related to said threshold is about 10-15% greater than the minimum possible prediction error that arises when applying a corresponding one of the actually available prediction modes.