Method and apparatus for encoding video pictures, and method and apparatus for decoding video pictures

• US 20060262216A1
• Filed: 03/29/2006
• Published: 11/23/2006
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: InterDigital Madison Patent Holdings (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Chen, Ying, Zhai, Jiefu
• Granted Patent: US 7,847,861 B2
• Time in Patent Office: Days
• US Class Current: 348/394.100
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/33 in the spatial domain
• 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 19/463 by compressing encoding parameters before transmission
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

The H.264 standard has introduced a new coding method for intra-coded pictures, which is named “intra prediction”. The basic idea of intra prediction is to predict a block using reconstructed neighbour pixels. Thus, only the residual information needs to be encoded. Scalable video coding adds some scalable extension to H.264, in terms of spatial, temporal and SNR scalability. An improved encoding method for scalable video comprises generating from a video picture a first and a second picture with higher resolution than the first picture, wherein each macroblock in the first picture has a plurality of corresponding macroblocks in the second picture, intra-coding the first picture on macroblock level, wherein for each macroblock a prediction direction is determined, generating a first residual picture, intra-coding the second picture on macroblock level, wherein for each macroblock the prediction direction of the corresponding macroblock of the first picture is reused, and generating a second residual picture.

Claims

1. Method for encoding video pictures, the method comprising the steps of

generating from a video picture a first and a second picture, wherein the second picture has a higher resolution than the first picture and each macroblock in the first picture has a plurality of corresponding macroblocks in the second picture;

intra-coding the first picture on macroblock level, wherein macroblocks are predicted and for a first predicted macroblock a prediction direction is determined; and

intra-coding the second picture on macroblock level, wherein for macroblocks corresponding to said first macroblock, instead of determining the prediction direction, the prediction direction of the first macroblock of the first picture is reused without modification of the direction.

2. Method according to claim 1, wherein the only modification performed on the prediction direction is scaling according to the resolution difference between the first and the second picture.

3. Method according to claim 1, further comprising the steps of

generating a first residual picture being the difference between the first picture and the intra-coded first picture;

and

generating a second residual picture being the difference between the second picture and the intra-coded second picture.

4. Method according to claim 1, wherein intra-coding of a picture on macroblock level comprises the steps of

defining a plurality of subblocks of a macroblock;

selecting a first subblock from the defined subblocks or from subblocks of a neighboring macroblock;

defining a prediction direction within the macroblock;

performing a prediction for a second subblock within the macroblock using the selected first subblock and the prediction direction; and

generating residual information, the residual information being the difference between the predicted subblock and the actual second subblock.

5. Method for decoding video pictures, the method comprising the steps of

decoding an encoded first video picture, wherein the encoded first video picture is intra-coded and contains encoded macroblocks, and for each encoded macroblock prediction direction information and residual information;

decoding an encoded second video picture, wherein the encoded second video picture also contains encoded macroblocks, and wherein for decoding an encoded macroblock the prediction direction information from the corresponding encoded macroblock of the encoded first video picture is reused, wherein no further directional information is added to the prediction direction information.

6. Method according to claim 5, wherein the only modification performed on the prediction direction information is scaling according to the resolution difference between the first and the second picture.

7. Method according to the claim 6, wherein the decoding of the encoded second video picture comprises the steps of

extracting from the encoded second video data first macroblock data including first subblock data and first residual update data;

extracting from the encoded first video picture first prediction direction data referring to the first macroblock data;

decoding a first subblock of the first macroblock from the encoded first macroblock data;

predicting from the first subblock and the first prediction information a second subblock of the first macroblock; and

updating the predicted second subblocks of the first macroblock with the extracted first residual update data.

8. Signal containing data for a first and a second video picture being intra-coded on macroblock level using prediction direction information, wherein the second picture has a higher resolution than the first picture and each macroblock of the first picture has a plurality of corresponding macroblocks of the second picture, and wherein for a macroblock within the second picture corresponding to a first macroblock of the first picture the only prediction direction information is an indication indicating that for its encoding the prediction direction information of said macroblock of the first picture was used.

9. Apparatus for encoding video pictures including

means for generating from a video picture a first and a second picture, wherein the second picture has a higher resolution than the first picture and each macroblock in the first picture has a plurality of corresponding macroblocks in the second picture;

means for intra-coding the first picture on macroblock level, wherein macroblocks are predicted and for each predicted macroblock a prediction direction is determined;

means for generating a first residual picture being the difference between the first picture and the intra-coded first picture;

means for intra-coding the second picture on macroblock level, wherein for each macroblock the prediction direction of the corresponding macroblock of the first picture is reused without modification of the direction; and

means for generating a second residual picture being the difference between the second picture and the intra-coded second picture.

10. Apparatus according to claim 9, wherein the only modification performed on the prediction direction is scaling according to the resolution difference between the first and the second picture.

11. Apparatus according to claim 9, further including

means for defining a plurality of subblocks of a macroblock;

means for selecting a first subblock from the defined subblocks or from subblocks of a neighboring macroblock;

means for defining a prediction direction within the macroblock;

means for performing a prediction of a second subblock within the macroblock using the selected first subblock and the prediction direction; and

means for generating residual information, the residual information being the difference between the predicted subblock and the actual second subblock.

12. Apparatus for decoding video pictures including

means for decoding an encoded first video picture, wherein the encoded first video picture is intra-coded and contains encoded macroblocks, and for each encoded macroblock prediction direction information and residual information;

means for decoding an encoded second video picture, wherein the encoded second video picture also contains encoded macroblocks, and for decoding an encoded macroblock the prediction direction information from the corresponding encoded macroblock of the encoded first video picture is used, wherein no further directional information is added to the prediction direction information.

13. Apparatus according to claim 12, further including

means for extracting from the encoded second video data first macroblock data including first subblock data and first residual update data;

means for extracting from the encoded first video picture first prediction direction data referring to the first macroblock data;

means for decoding a first subblock of the first macroblock from the encoded first macroblock data;

means for predicting from the first subblock and the first prediction information a second subblock of the first macroblock; and

means for updating the predicted second subblocks of the first macroblock with the extracted first residual update data.