VIDEO CODING WITH ADAPTIVE FILTERING FOR MOTION COMPENSATED PREDICTION

• US 20080089417A1
• Filed: 10/09/2007
• Published: 04/17/2008
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ye, Yan, Bao, Yiliang
• Granted Patent: US 9,014,280 B2
• Time in Patent Office: Days
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• 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 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• 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 19/523 with sub-pixel accuracy
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop

Abstract

This disclosure is directed to video coding techniques that support normal single layer video coding, or scalable video coding with features such as signal-to-noise ratio (SNR) scalability and spatial scalability. A video coding device may implement these techniques in a video decoder that includes a motion compensation module and a filter. The motion compensation module decodes a prediction frame from a digital video signal, wherein the motion compensation module determines each block of the inter-coded frame from motion vectors encoded in the digital video signal. The filter adaptively filters one or more of the inter-coded blocks based on a signal either encoded or inferred from the digital video signal. In some instances, the video decoder may adaptively apply different filter functions, one in the horizontal and another in the vertical direction, based on the signal. By implementing these techniques, the video decoder may increase the visual quality of the resulting decoded digital video signal while reducing complexity.

Claims

1. A method comprising:

applying motion compensation to blocks within a video frame to generate prediction video blocks; and

adaptively adjusting the motion compensation to apply either a first filter mode or a second filter mode to each of the blocks based on a filter mode decision.

2. The method of claim 1, further comprising applying a 3-tap filter to the blocks for motion vectors that point to integer pixel locations.

3. The method of claim 1, further comprising generating the filter mode decision based on one of a signal encoded in the video bitstream or one or more characteristics of the video frame.

4. The method of claim 1, wherein the blocks comprise blocks in an enhancement layer of a scalable video coding frame.

5. The method of claim 1, further comprising applying a motion compensation filter in the first filter mode, and applying a 3-tap filter in the second filter mode.

6. The method of claim 5, further comprising applying the 3-tap filter and the motion compensation filter in the second filter mode, wherein the motion compensation filter includes a 2-tap filter.

7. The method of claim 5, further comprising, in the second filter mode, applying a filter that combines the 3-tap filter with an interpolation filter.

8. The method of claim 7, wherein the interpolation filter includes a 2-tap filter, the method further comprising, in the second filter mode, applying the 3-tap filter in one of a horizontal dimension and a vertical dimension, and applying the 2-tap filter in another of the horizontal and vertical dimensions.

9. The method of claim 7, wherein the interpolation filter includes a 2-tap filter, the method further comprising, in the second filter mode:

applying the 3-tap filter in the horizontal dimension and applying the 2-tap filter in the vertical dimension when a motion vector points to an integer pixel location in the horizontal dimension and to a fractional pixel location in the vertical dimension; and

applying the 3-tap filter in the vertical dimension and applying the 2-tap filter in the horizontal dimension when a motion vector points to an integer pixel location in the vertical dimension and to a fractional pixel location in the horizontal dimension.

10. The method of claim 1, further comprising adaptively adjusting the motion compensation on one of a block-by-block, macroblock-by-macroblock, slice-by-slice, or frame-by-frame basis.

11. A video coding device comprising:

a motion compensation module that applies motion compensation to blocks within a video frame to generate prediction video blocks; and

a control module that adaptively adjusts the motion compensation to apply either a first filter mode or a second filter mode to each of the blocks based on a filter mode decision.

12. The device of claim 11, wherein the control module applies a 3-tap filter to the blocks for motion vectors that point to integer pixel locations.

13. The device of claim 11, wherein the control module generates the filter mode decision based on one of a signal encoded in the video bitstream or one or more characteristics of the video frame.

14. The device of claim 11, wherein the blocks comprise blocks in an enhancement layer of a scalable video coding frame.

15. The device of claim 11, wherein the motion compensation module applies a motion compensation filter in the first filter mode, and applying a 3-tap filter in the second filter mode.

16. The device of claim 15, wherein the motion compensation module applies the 3-tap filter and the motion compensation filter in the second filter mode, wherein the motion compensation filter includes a 2-tap filter.

17. The device of claim 15, wherein the motion compensation module, in the second filter mode, applies a filter that combines the 3-tap filter with an interpolation filter.

18. The device of claim 17, wherein the interpolation filter includes a 2-tap filter, and wherein the motion compensation module, in the second filter mode, applies the 3-tap filter in one of a horizontal dimension and a vertical dimension, and applies the 2-tap filter in another of the horizontal and vertical dimensions.

19. The device of claim 17, wherein the interpolation filter includes a 2-tap filter, and wherein the motion compensation module, in the second filter mode, applies the 3-tap filter in the horizontal dimension and the 2-tap filter in the vertical dimension when a motion vector points to an integer pixel location in the horizontal dimension and to a fractional pixel location in the vertical dimension, and applies the 3-tap filter in the vertical dimension and the 2-tap filter in the horizontal dimension when a motion vector points to an integer pixel location in the vertical dimension and to a fractional pixel location in the horizontal dimension.

20. The device of claim 11, wherein the control module adaptively adjusts the motion compensation on one of a block-by-block, macroblock-by-macroblock, slice-by-slice, or frame-by-frame basis.

21. The device of claim 11, wherein the device is one of a wireless communication device handset or an integrated circuit device.

22. A video coding device comprising:

means for applying motion compensation to blocks within a video frame to generate prediction video blocks; and

means for adaptively adjusting the motion compensation to apply either a first filter mode or a second filter mode to each of the blocks based on a filter mode decision.

23. The device of claim 22, further comprising means for applying a 3-tap filter to the blocks for motion vectors that point to integer pixel locations.

24. A computer program product comprising a computer-readable medium comprising instructions to cause a processor to:

apply motion compensation to blocks within a video frame to generate prediction video blocks; and

adaptively adjust the motion compensation to apply either a first filter mode or a second filter mode to each of the blocks based on a filter mode decision.

25. The computer program product of claim 24, further comprising instructions to cause the processor to apply a 3-tap filter to the blocks for motion vectors that point to integer pixel locations.