Method for processing image on basis of inter-prediction mode and device therefor
Disclosed herein are a method for decoding a video signal and a device therefor. Specifically, a method for decoding an image based on an inter prediction mode may include: if a merge mode is applied to a current block, generating a merge candidate list by using a spatial neighboring block and a temporal neighboring block of the current block; obtaining a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list; deriving a motion vector of each of subblocks included in the current block based on a motion vector of the candidate used for the inter prediction of the current block; and generating a prediction sample of the current block by using the motion vector of each of subblocks.
1. A method for decoding an image based on an inter prediction mode, comprising:
based on that a merge mode is applied to a current block, generating, by a processor, a merge candidate list by using a spatial neighboring block and a temporal neighboring block of the current block;
obtaining, by the processor, a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
deriving, by the processor, a motion vector of each subblocks included in the current block based on a motion vector of the candidate used for the inter prediction of the current block; and
generating, by the processor, a prediction sample of the current block based on the motion vector of each subblocks,
wherein the step of generating the merge candidate list comprises:
identifying whether a width and a height of the current block is less than a pre-defined minimum size; and
based on that the width and the height of the current block is greater than or equal to the pre-defined minimum size, adding a block which is located in a collocated picture of the current block and specified by a motion vector of the spatial neighboring block to the merge candidate list as the temporal neighboring block.
2. The method of claim 1 ,
wherein generating the merge candidate list comprises adding a block in the collocated picture specified by a motion vector of a first spatial neighboring block to the merge candidate list as the temporal neighboring block, the first spatial neighboring block being determined based on a pre-defined order among two or more spatial neighboring blocks of the current block.
3. The method of claim 1 ,
wherein a width of the subblock is set to 8 and a height of the subblock is set to 8.
4. The method of claim 3 ,
wherein the pre-defined minimum size is set to 8.
5. A method for encoding an image based on an inter prediction mode, comprising:
based on that a merge mode is applied to a current block, generating, by a processor, a merge candidate list by using a spatial neighboring block and a temporal neighboring block of the current block;
signaling, by the processor, a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
deriving, by the processor, a motion vector of each subblocks included in the current block based on a motion vector of the candidate used for the inter prediction of the current block; and
generating, by the processor, a prediction sample of the current block based on the motion vector of each subblocks,
wherein the step of generating the merge candidate list comprises:
identifying whether a width and a height of the current block is less than a pre-defined minimum size; and
based on that the width and the height of the current block is greater than or equal to the pre-defined minimum size, adding a block which is located in a collocated picture of the current block and specified by a motion vector of the spatial neighboring block to the merge candidate list as the temporal neighboring block.
6. The method of claim 5 , wherein generating the merge candidate list comprises:
adding a block in the collocated picture specified by a motion vector of a first spatial neighboring block to the merge candidate list as the temporal neighboring block, the first spatial neighboring block being determined based on a pre-defined order among two or more spatial neighboring blocks of the current block.
7. The method of claim 5 , wherein a width of the subblock is set to 8 and a height of the subblock is set to 8.
8. The method of claim 7 , wherein the pre-defined minimum size is set to 8.
9. A non-transitory decoder-readable medium for storing a bitstream generated by a video encoder, the bitstream comprising:
information used for generating a merge candidate list by using a spatial neighboring block and a temporal neighboring block of a current block based on that a merge mode is applied to the current block;
information related to a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
information used for deriving a motion vector of each subblocks included in the current block based on a motion vector of the candidate used for the inter prediction of the current block; and
information used for generating a prediction sample of the current block based on the motion vector of each subblocks,
wherein the information used for generating the merge candidate list comprises:
information used for adding a block which is located in a collocated picture of the current block and specified by a motion vector of the spatial neighboring block to the merge candidate list as the temporal neighboring block, based on that it is identified that a width and a height of the current block is greater than or equal to a pre-defined minimum size.