Video encoding and decoding
First Claim
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.
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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.
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Citations
17 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.
- 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.
- 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.
- 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.
- 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.
- 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.
Specification