Video encoding and decoding

• US 8,824,555 B2
• Filed: 03/08/2012
• Issued: 09/02/2014
• Est. Priority Date: 03/09/2011
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Laroche, Guillaume, Onno, Patrice
• Primary Examiner(s): Ustaris, Joseph
• Assistant Examiner(s): NAWAZ, TALHA M
• Application Number:
  US14/003,564
• Publication Number:
  US 20140064372A1
• Time in Patent Office: 908 Days
• Field of Search: 375/240
• US Class Current: 375/240.16
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/107 between spatial and temporal predictive coding, e.g. picture refresh
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/43 Hardware specially adapted for motion estimation or compensation
• 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 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 19/513 Processing of motion vectors
• CPC Class Codes: H04N 19/52 by predictive encoding
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/61 in combination with predictive coding

Abstract

A temporal motion vector predictor is includable, together with one or more spatial motion vector predictors, in a set of motion vector predictors for a block to encode of a current frame. A method of determining the temporal motion vector predictor comprises selecting as the temporal predictor one motion vector from among motion vectors in a reference block of a reference frame different from the current frame. The reference block is a block of the reference frame collocated with the block to encode or a block of the reference frame neighboring the collocated block. The selection is based on a diversity criterion for achieving diversity among the predictors of the set.

This can reduce the motion vector memory requirements with no or no significant additional coding efficiency penalty. Alternatively, even if the motion vector memory is not reduced in size, coding efficiency improvements can be achieved.

Claims

1. A method of generating a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors in the set is at least one, the method comprising determining the one temporal motion vector predictor of the set by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

2. A method as claimed in claim 1, wherein the at least one said spatial predictor is selected before the temporal predictor is determined, and the determination of the temporal predictor is carried out in dependence upon the selected spatial predictor(s).

3. A method of decoding a bitstream comprising an encoded sequence of digital images, at least one portion of an image being encoded by motion compensation with respect to a reference image, said method comprising generating a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors in the set is at least one, said generating comprising determining the one temporal motion vector predictor of the set by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position, in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

4. A method as claimed in claim 3, wherein said predetermined position is the top left position in the block diagonally below and to the right of the collocated block.

5. A method as claimed in claim 3, wherein the at least one said spatial predictor is selected before the temporal predictor is determined, and the determination of the temporal predictor is carried out in dependence upon the selected spatial predictor(s).

6. Apparatus for generating a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors is at least one, said apparatus comprising a temporal predictor determining unit configured to determine the one temporal motion vector predictor by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

7. Apparatus as claimed in claim 6, comprising a spatial predictor selecting unit configured to select at least one said spatial predictor before the temporal predictor is determined, the temporal predictor determining unit being operable to determine the temporal predictor in dependence upon the selected spatial predictor(s).

8. Apparatus as claimed in claim 6 wherein said predetermined position is the top left position in the block diagonally below and to the right of the collocated block.

9. Apparatus for decoding a bitstream comprising an encoded sequence of digital images, at least one portion of an image being encoded by motion compensation with respect to a reference image, comprising a motion vector predictor generating unit configured to generate a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors is at least one, said motion vector predictor generating unit comprising a temporal predictor determining unit configured to determine the one temporal motion vector predictor by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

10. Apparatus as claimed in claim 9, wherein said predetermined position is the top left position in the block diagonally below and to the right of the collocated block.

11. Apparatus as claimed in claim 9, comprising a spatial predictor selecting unit configured to select at least one said spatial predictor before the temporal predictor is determined, the temporal predictor determining unit being operable to determine the temporal predictor in dependence upon the selected spatial predictor(s).

12. A non-transitory computer readable carrier medium storing a program which, when run on a computer or processor, causes the computer or processor to carry out a method of generating a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors in the set is at least one, the program comprising a code portion which determines the one temporal motion vector predictor of the set by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

13. A medium as claimed in claim 12, wherein said predetermined position is the top left position in the block diagonally below and to the right of the collocated block.

14. A medium as claimed in claim 12, wherein the program comprises a code portion which selects at least one said spatial predictor before the temporal predictor is determined, and wherein the determination of the temporal predictor is carried out in dependence upon the selected spatial predictor(s).

15. A non-transitory computer readable medium storing a program which, when run on a computer or processor, causes the computer or processor to carry out a method of decoding a bitstream comprising an encoded sequence of digital images, at least one portion of an image being encoded by motion compensation with respect to a reference image, the program comprising a code portion which generates a set of motion vector predictors for a block to decode forming part of a current video frame that is to be decoded, wherein the number of temporal motion vector predictors in the set is one and the number of spatial motion vector predictors in the set is at least one, the generating comprising determining the one temporal motion vector predictor of the set by selecting as the one temporal motion vector predictor, the motion vector at a predetermined position in a neighboring block of a reference frame neighboring a block of the reference frame collocated with said block to decode, the neighboring block being diagonally below and to the right of the block of the reference frame collocated with said block to decode, and the predetermined position being a top left position in that neighboring block.

16. A medium as claimed in claim 15, wherein said predetermined position is the top left position in the block diagonally below and to the right of the collocated block.

17. A medium as claimed in claim 15, wherein the program comprises a code portion which selects at least one said spatial predictor before the temporal predictor is determined, and wherein the determination of the temporal predictor is carried out in dependence upon the selected spatial predictor(s).