Methods and systems for intra block copy coding with block vector derivation

• US 9,877,043 B2
• Filed: 06/18/2015
• Issued: 01/23/2018
• Est. Priority Date: 06/19/2014
• Status: Active Grant

• Current Assignee: VID SCALE Inc. (InterDigital, Inc.)
• Original Assignee: VID SCALE Inc. (InterDigital, Inc.)
• Inventors: He, Yuwen, Ye, Yan, Xiu, Xiaoyu
• Primary Examiner(s): Olson, Jason
• Application Number:
  US14/743,657
• Publication Number:
  US 20150373366A1
• Time in Patent Office: 950 Days
• Field of Search: 37524016
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/463 by compressing encoding parameters before transmission
• CPC Class Codes: H04N 19/521 for estimating the reliability of the determined motion vectors or motion vector field, e.g. for smoothing the motion vector field or for correcting motion vectors
• 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
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• CPC Class Codes: H04N 19/94 Vector quantisation

Abstract

Systems and methods are described for encoding and decoding video using derived block vectors as predictors in intra block copy mode. In an exemplary encoding method, an encoder identifies at least a first candidate block vector for the prediction of an input video block, where the first candidate block vector points to a first candidate block. The encoder then identifies a first predictive vector (e.g. a block vector or a motion vector) that was used to encode the first candidate block. From the first candidate block vector and the first predictive vector, the encoder generates a derived predictive vector from the first candidate block vector and the first predictive vector. The encoder then encodes the video block in the bit stream using the derived predictive vector for the prediction of the input video block.

Claims

1. A video coding method of deriving a predictive vector, the method comprising:

identifying a first candidate block vector for prediction of a video block, wherein the first candidate block vector points to a first candidate block;

identifying at least a first predictive vector associated with the first candidate block;

generating a derived predictive vector from the first candidate block vector and the first predictive vector; and

coding the video block using the derived predictive vector.

2. The method of claim 1, wherein coding the video block using the derived predictive vector includes:

identifying a second candidate block that the derived predictive vector points to; and

predicting the video block using the second candidate block.

3. The method of claim 1, wherein coding the video block includes signaling the first candidate block vector in a bit stream.

4. The method of claim 3, wherein coding the video block further includes signaling the first predictive vector in the bit stream.

5. The method of claim 3, wherein coding the video block further includes signaling a flag in the bit stream, wherein a first value of the flag indicates that the derived predictive vector is used to code the video block.

6. The method of claim 5, wherein a second value of the flag indicates that the first candidate block vector is used to code the video block.

7. The method of claim 1, wherein the derived predictive vector is generated by adding the first candidate block vector and the first predictive vector.

8. The method of claim 7, wherein the first candidate block vector and the first predictive vector have different precisions, and wherein adding the first block vector and the first predictive vector is performed after aligning them to the same precision.

9. The method of claim 1, wherein the first predictive vector is a second block vector, and the derived predictive vector is a derived block vector.

10. The method of claim 9, wherein the derived block vector is generated by adding the first candidate block vector and the second block vector.

11. The method of claim 1, wherein the first predictive vector is a first motion vector, and the derived predictive vector is a derived motion vector.

12. The method of claim 11, wherein the derived motion vector is generated by adding the first candidate block vector and the first motion vector.

13. The method of claim 12, wherein the first candidate block vector and the first motion vector have different precisions, and wherein the derived motion vector is generated by aligning the precision of the first candidate block vector and the first motion vector and adding the precision aligned first candidate block vector and the precision aligned first motion vector.

14. The method of claim 13, wherein the precision aligned first candidate block vector and the precision aligned first motion vector are added according to the equation

MVd=BV0+((MV1+2)>

>

2),

where BV0 is the first candidate block vector, MV1 is the first motion vector, and MVd is the derived motion vector.

15. The method of claim 1, wherein the video coding method further includes inserting the derived predictive vector into a merge candidate list.

16. The method of claim 15, further comprising determining whether the derived predictive vector is valid, wherein the derived predictive vector is inserted into the merge candidate list only after determining that the derived predictive vector is valid.

17. The method of claim 16, wherein determining whether the derived predictive vector is valid comprises:

identifying a second candidate block that the derived predictive vector points to;

determining whether all samples in the second candidate block are available; and

determining that the derived predictive vector is valid if all samples in the second candidate block are available, and determining that the derived predictive vector is not valid if at least one sample in the second candidate block is not available.

18. The method of claim 17, wherein a sample in the second candidate block is unavailable if any of the following is true:

the sample is not yet coded, or

the sample is in a different slice or in a different tile, or

the sample is out of a video picture boundary.

19. The method of claim 15, wherein coding the video block using the derived predictive vector includes providing an index identifying the derived predictive vector in the merge candidate list.

20. A method of decoding a coded video block from a bit stream encoding a video, the method comprising:

identifying at least a first candidate block vector for prediction of the coded video block, wherein the first candidate block vector points to a first candidate block;

identifying at least a first predictive vector associated with the first candidate block;

generating a derived predictive vector from the first candidate block vector and the first predictive vector; and

decoding the coded video block using the derived predictive vector.