Method and apparatus for processing video signal
A method for decoding a video according to the present invention may comprise: obtaining a weighted prediction parameter of a current block, determined, based on the weighted prediction parameter, weights applying to a first prediction block generated based on a first reference picture and a second prediction block generated based on a second reference picture, and obtaining, based on a weighted sum of the first prediction block and the second prediction block, a final prediction block of the current block.
1. A method for of decoding a video, the method comprising:
obtaining an L0 prediction block of a current block based on an L0 reference picture of the current block;
obtaining an L1 prediction block of the current block based on an L1 reference picture of the current block;
determining a first weight applying to the L0 prediction block and a second weight applying to the L1 prediction block; and
obtaining a bi-prediction block by performing a weighted sum of the L0 prediction block and the L1 prediction block based on the first weight and the second weight,
wherein one of the first weight and the second weight is determined based on index indicating one among a plurality of weight candidates, and
wherein a number of the weight candidates is determined based on temporal directions of the L0 reference picture and the L1 reference picture.
2. The method of claim 1 , wherein the other of the first weight and the second weight is determined by subtracting one determined by the index from a constant value.
3. The method of claim 1 , wherein the index is derived by information decoded from a bistream, and
wherein the information is binarized with a truncated unary binarization.
4. The method of claim 3 , wherein a maximum bit-length of the information is determined based on temporal directions of the L0 reference picture and the L1 reference picture.
5. The method of claim 1 , wherein the number of the weight candidates is different between when both of temporal directions of the L0 reference picture and the L1 reference picture are previous to or subsequent to a current picture, and when temporal directions of the L0 reference picture and the L1 reference picture are different from each other.
6. The method of claim 1 , wherein the index is derived from a neighboring block adjacent to the current block.
7. A method of encoding a video, the method comprising:
obtaining an L0 prediction block of a current block based on an L0 reference picture of the current block;
obtaining an L1 prediction block of the current block based on an L1 reference picture of the current block;
determining a first weights applying to the L0 prediction block and a second weight applying to the L1 prediction block; and
generating a bi-prediction block by performing a weighted sum of the L0 prediction block and the L1 prediction block based on the first weight and the second weight,
wherein one of the first weight and the second weight is determined among a plurality of weight candidates, and
wherein a number of the weight candidates is determined based on temporal directions of the L0 reference picture and the L1 reference picture.
8. The method of claim 7 , wherein information indicating selected one among the plurality of weight candidates is encoded, and
wherein the information is binarized with a truncated unary binarization.
9. The method of claim 7 , wherein the number of the weight candidates is different between when both of temporal directions of the L0 reference picture and the L1 reference picture are previous to or subsequent to a current picture, and when temporal directions of the L0 reference picture and the L1 reference picture are different from each other.
10. A non-transitory computer-readable medium storing instructions which when executed by a processor cause the processor to:
obtaining an L0 prediction block of a current block based on an L0 reference picture of the current block;
obtaining an L1 prediction block of the current block based on an L1 reference picture of the current block;
determining a first weight applying to the L0 prediction block and a second weight applying to the L1 prediction block; and
generating a bi-prediction block by performing a weighted sum of the L0 prediction block and the L1 prediction block based on the first weight and the second weight,
wherein one of the first weight and the second weight is determined among a plurality of weight candidates, and
wherein a number of the weight candidates is determined based on temporal directions of the L0 reference picture and the L1 reference picture.