SCALABLE VIDEO CODING WITH FILTERING OF LOWER LAYERS

• US 20080095238A1
• Filed: 10/18/2007
• Published: 04/24/2008
• Est. Priority Date: 10/18/2006
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: WU, Hsi-Jung, SHI, Xiaojin, HASKELL, Barin Geoffry
• Application Number:
  US11/874,533
• Publication Number:
  US 20080095238A1
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/80 Details of filtering operations specially adapted for video compression, e.g. for pixel interpolation H04N19/635, H04N19/86 take precedence

Abstract

A First Improvement is Described for Prediction of Motion Vectors to be Used in Prediction of video data for enhancement layer data. Arbitrary pixelblock partitioning between base layer data and enhancement layer data raises problems to identify base layer motion vectors to be used as prediction sources for enhancement layer motion vectors. The disclosed method develops enhancement layer motion vectors by scaling a base layer pixelblock partition map according to a size difference between the base layer video image and the enhancement layer video image, then identified scale base layer pixelblocks that are co-located with the enhancement layer pixelblocks for which motion vector prediction is to be performed. Motion vectors from the scaled co-located base layer pixelblocks are averaged, weighted according to a degree of overlap between the base layer pixelblocks and the enhancement layer pixelblock. Another improvement is obtained by filtering recovered base layer image data before being provided to an enhancement layer decoder. When a specified filter requires image data outside a prediction region available from a base layer decoder, the prediction region data may be supplemented with previously-decoded data from an enhancement layer at a border of the prediction region.

Claims

1. A method of predicting motion vectors in a multi-layer video decoding process, comprising:

determining a size difference between recovered video data obtained solely by a base layer decode process and recovered video data obtained from an enhancement layer decode process;

scaling a base layer pixelblock partition map according to the determined size difference;

predicting a motion vector of an enhancement layer pixelblock according to;

determining which base layer pixelblock(s), when scaled according to the size difference, are co-located with the enhancement layer pixelblock,

scaling motion vectors of the co-located base layer pixelblock(s) according to the size difference, and

averaging the scaled motion vectors of the co-located base layer pixelblock(s), wherein the averaging weight contribution of each scaled motion vector according to a degree of overlap between the enhancement layer pixelblock and the respective scaled base layer pixelblock.

2. The method of claim 1, further comprising, when a co-located base layer pixelblock does not have a motion vector associated with it, interpolating a motion vector for the respective base layer pixelblock from motion vectors of neighboring base layer pixelblocks.

3. The method of claim 1, further comprising developing a partition map from enhancement layer pixelblock definitions and base layer pixelblocks received from a communication channel.

4. The method of claim 1, further comprising predicting data of the enhancement layer pixelblock from stored decoded base layer image data according to the predicted motion vector.

5. The method of claim 1, further comprising predicting data of the enhancement layer pixelblock from stored decoded enhancement layer image data according to the predicted motion vector.

6. A multi-layer video decoder, comprising:

a base layer decoder to generate recovered base layer image data from base layer coded video provided in a channel according to temporal prediction techniques, and

an enhancement layer decoder to generate recovered enhancement layer image data from enhancement layer coded video provided in a channel according to temporal prediction techniques, comprising;

a partition map that stores information representing pixelblock partitioning of the base layer image data and of the enhancement layer image data and

a motion compensation predictor that predicts recovered enhancement layer image data from previously decoded image data according to a motion vectors, a motion vector of at least one enhancement layer pixelblock being predicted according to;

determining which base layer pixelblock(s), when scaled according to a size difference between base layer pixelblocks and enhancement layer pixelblocks, are co-located with the enhancement layer pixelblock,

scaling motion vectors of the co-located base layer pixelblock(s) according to the size difference, and

averaging the scaled motion vectors of the co-located base layer pixelblock(s), wherein the averaging weight contribution of each scaled motion vector according to a degree of overlap between the enhancement layer pixelblock and the respective scaled base layer pixelblock.

7. The decoder of claim 6, wherein, when a co-located base layer pixelblock does not have a motion vector associated with it, the motion compensation predictor interpolates a motion vector for the respective base layer pixelblock from motion vectors of neighboring base layer pixel blocks.

8. The decoder of claim 6, wherein the partition map derives the partitioning information from enhancement layer pixelblock definitions and base layer pixelblocks received from a communication channel.

9. The decoder of claim 6, wherein the previously decoded image data is stored decoded base layer image data.

10. The decoder of claim 6, wherein the previously decoded image data is stored decoded enhancement layer image data.

11. A video decoding method comprising:

decoding recovered prediction region data from base layer coded video provided in a channel according to temporal prediction techniques,

generating composite image data as a merger between the recovered prediction region data with border data taken from previously-decoded recovered enhancement layer data,

filtering the composite image data, and

generating new recovered enhancement layer image data from the filtered composite image data and from enhancement layer coded video provided in a channel according to temporal prediction techniques.

12. The method of claim 11, wherein an amount of data to be taken as a border region is determined from a type of filtering to be applied.

13. The method of claim 11, wherein the filtering is deblocking filtering.

14. The method of claim 11, wherein the filtering is ringing filtering.

15. The method of claim 11, wherein the filtering is edge detection filtering.

16. A video decoder, comprising:

a base layer decoder to generate recovered base layer image data from base layer coded video provided in a channel according to temporal prediction techniques;

an enhancement layer decoder to generate recovered enhancement layer image data from enhancement layer coded video provided in a channel according to temporal prediction techniques, the enhancement layer decoding having storage for reference frames of recovered enhancement layer image data;

a composite image generator having inputs for recovered base layer image data and reference frames of recovered enhancement layer image data, the generator to merge prediction region data from the recovered base layer image data with a border region from the reference frames of recovered enhancement layer image data, the prediction region having been scaled to account for any size difference between the recovered base layer data and the recovered enhancement layer image data, wherein the border region is taken from a spatial area that borders a spatial area occupied by the prediction region;

a filter that applies image filtering to the merged data, wherein an output of the filter is input to the enhancement layer decoder as reference image data for temporal prediction.

17. The decoder of claim 16, wherein a width of the border region is determined from a type of image filtering to be applied.

18. The decoder of claim 16, wherein the image filtering is deblocking filtering.

19. The decoder of claim 16, wherein the image filtering is ringing filtering.

20. The decoder of claim 16, wherein the image filtering is edge detection filtering.