METHODS AND SYSTEMS FOR MOTION VECTOR DERIVATION AT A VIDEO DECODER

• US 20110002390A1
• Filed: 09/25/2009
• Published: 01/06/2011
• Est. Priority Date: 07/03/2009
• Status: Active Grant

• Current Assignee: Tahoe Research Limited (f/k/a Learndale Limited) (Vector Capital Corporation)
• Original Assignee: Intel Corporation
• Inventors: Jiang, Hong, Chiu, Yi-Jen, Xu, Lidong
• Granted Patent: US 9,654,792 B2
• 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 19/52 by predictive encoding
• 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 19/577 Motion compensation with bidirectional frame interpolation, i.e. using B-pictures

Abstract

Method and apparatus for deriving a motion vector at a video decoder. A block-based motion vector may be produced at the video decoder by utilizing motion estimation among available pixels relative to blocks in one or more reference frames. The available pixels could be, for example, spatially neighboring blocks in the sequential scan coding order of a current frame, blocks in a previously decoded frame, or blocks in a downsampled frame in a lower pyramid when layered coding has been used.

Claims

1. A method, comprising:

at a video decoder, identifying a first block of previously decoded pixels corresponding to a target block in a current frame;

determining a first motion vector for the first block of previously decoded pixels relative to a corresponding block in a first reference frame; and

using the determined motion vector to perform motion compensation and decoding for the target block.

2. The method of claim 1, wherein the first block of previously decoded pixels neighbors the target block in the current frame.

3. The method of claim 2, further comprising:

identifying a second block of previously decoded pixels;

determining a second motion vector, for the second block of previously decoded pixels, relative to a corresponding block in a second reference frame; and

using the second motion vector, in addition to the first motion vector, to perform the motion compensation and decoding for the target block in the current frame,

wherein the first reference frame and the second reference frame are succeeding and previous reference frames, respectively, relative to the current frame.

4. The method of claim 1, wherein the first block of previously decoded pixels is located in a previous frame and corresponds to the target block in the current frame.

5. The method of claim 4, further comprising:

identifying a second block of previously decoded pixels that resides in a succeeding frame and corresponds to the target block in the current frame;

determining a second motion vector, for the second block of previously decoded pixels, relative to corresponding block in a succeeding reference frame; and

using the second motion vector, in addition to the first motion vector, to perform the motion compensation and decoding for the target block in the current frame.

6. The method of claim 1, wherein the first block of previously decoded pixels is located in a frame in a lower downsampled layer relative to a target layer in which the current frame is located, the frame in the lower layer corresponding to the current frame, and wherein the first reference frame is located in the lower layer.

7. The method of claim 1, further comprising:

calculating a first rate distortion cost metric, collectively for said identifying of the first block of previously decoded pixels, said determining of the first motion vector, and said using of the determined motion vector to perform the motion compensation and decoding for the target block;

calculating a second rate distortion cost metric, for an alternative decoding process;

comparing the first and second rate distortion cost metrics; and

selecting a preferred decoding process on the basis of said comparison.

8. A computer program product including a computer readable medium having computer program logic stored therein, the computer program logic including:

a decoded block identification module for causing a processor to identify a first block of previously decoded pixels, where the first block of previously decoded pixels corresponds to a target block in a current frame;

a motion vector determination module for causing the processor to determine a first motion vector for the first block of previously decoded pixels, relative to a corresponding block in a first reference frame; and

a motion vector application module for causing the processor to perform motion compensation and decoding for the target block using the determined first motion vector.

9. The computer program product of claim 8, wherein the first block of previously decoded pixels neighbors the target block in the current frame.

10. The computer program product of claim 9, wherein

the decoded block identification module further causes the processor to identify a second block of previously decoded pixels;

the motion vector determination module further causes the processor to determine a second motion vector, for the second block of previously decoded pixels, relative to a corresponding block in a second reference frame; and

the motion vector application module further causes the processor to use the second motion vector, in addition to the first motion vector, to perform the motion compensation and decoding for the target block in the current frame,

wherein the first reference frame and the second reference frame are succeeding and previous reference frames, respectively, relative to the current frame.

11. The computer program product of claim 8, wherein the first block of previously decoded pixels is located in a previous frame and corresponds to the target block in the current frame.

12. The computer program product of claim 11, wherein

the decoded block identification module further causes the processor to identify a second block of previously decoded pixels that is located in a succeeding frame and corresponds to the target block in the current frame;

the motion vector determination module further causes the processor to determine a second motion vector, for the second block of previously decoded pixels, relative to a corresponding block in a succeeding reference frame; and

the motion vector application module further causes the processor to use the second motion vector, in addition to the first motion vector, to perform the motion compensation and decoding for the target block in the current frame.

13. The computer program product of claim 8, wherein the first block of previously decoded pixels is located in a frame in a lower downsampled layer relative to a target layer in which the current frame is located, the frame in the lower layer corresponding to the current frame, and wherein the first reference frame is located in the lower layer.

14. A system, comprising:

a processor; and

a memory in communication with said processor, said memory for storing a plurality of processing instructions for directing said processor to

identify a first block of previously decoded pixels corresponding to a target block in a current frame, wherein the first block of previously decoded pixels neighbors the target block in the current frame;

determine a first motion vector for the first block of previously decoded pixels relative to a corresponding block in a first reference frame; and

use the determined motion vector to perform motion compensation and decoding for the target block.

15. The system of claim 14, wherein the processor and memory are incorporated in a video decoder, and wherein the system further comprises a video encoder that sends compressed video data to the video decoder without providing a motion vector for the target block.

16. The system of claim 14, wherein said processing instructions further direct said processor to

identify a second block of previously decoded pixels;

determine a second motion vector, for the second block of previously decoded pixels, relative to a corresponding block in a second reference frame; and

use the second motion vector, in addition to the first motion vectors, to perform the motion compensation and decoding for the target block in the current frame,

wherein the first reference frame and the second reference frame are succeeding and previous reference frames, respectively, relative to the current frame.

17. The system of claim 14, wherein the first block of previously decoded pixels is located in a previous frame and corresponds to the target block in the current frame.

18. The system of claim 17, wherein said processing instructions further direct said processor to

identify a second block of previously decoded pixels that resides in a succeeding frame and corresponds to the target block in the current frame;

determine a second motion vector, for the second block of previously decoded pixels, relative to a corresponding block in a succeeding reference frame; and

use the second motion vector, in addition to the first motion vector, to perform the motion compensation and decoding for the target block in the current frame.

19. The system of claim 14, wherein the first block of previously decoded pixels is located in a frame in a lower downsampled layer relative to a target layer in which the current frame is located, the frame in the lower layer corresponding to the current frame, and wherein the first reference frame is located in the lower layer.

20. The system of claim 14, wherein said processing instructions further direct said processor to

calculate a first rate distortion cost metric, collectively for the identifying of the first block of previously decoded pixels, the determining of the first motion vector, and the using of the determined motion vector to perform the motion compensation and decoding for the target block;

calculate a second rate distortion cost metric, for an alternative decoding process;

compare the first and second rate distortion cost metrics; and

select a preferred decoding process on the basis of the comparison.