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. An apparatus for decoding a video signal based on an inter prediction mode, comprising:
a memory configured to store the video signal; and
a processor coupled with the memory,
wherein the processor is configured to:
generate 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;
obtain a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
derive a motion vector of each subblock included in the current block based on a motion vector of the candidate indicated by the merge index;
generate a prediction block of the current block based on the motion vector of each subblock;
perform inverse-transform on transformed coefficients of the current block to generate a residual block of the current block; and
generate a reconstructed block of the current block based on the prediction block and the residual block,
wherein the processor is further configured to add 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 a width and a height of the current block is greater than or equal to a pre-defined size.
2. The apparatus of claim 1 , the processor is further configured to add 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 apparatus 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 apparatus of claim 3 , wherein the pre-defined size is set to 8.
5. An apparatus for encoding a video signal based on an inter prediction mode, comprising:
a memory configured to store the video signal; and
a processor coupled with the memory,
wherein the processor is configured to:
generate 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;
generate a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
derive a motion vector of each subblocks included in the current block based on a motion vector of the candidate indicated by the merge index;
generate a prediction block of the current block based on the motion vector of each subblocks;
generate a residual block of the current block based on the prediction block; and
perform transform on the residual block,
wherein the processor is further configured to add 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 a width and a height of the current block is greater than or equal to a pre-defined size.
6. The apparatus of claim 5 , wherein the processor is further configured to add 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 apparatus 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 size is set to 8.
9. An apparatus for transmitting data, comprising:
a processor configured to obtain a bitstream for an image; and
a transmitter configured to transmit the data comprising the bitstream,
wherein the processor is configured to:
generate 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;
generate a merge index indicating a candidate to be used for an inter prediction of the current block in the merge candidate list;
derive a motion vector of each subblocks included in the current block based on a motion vector of the candidate indicated by the merge index;
generate a prediction block of the current block based on the motion vector of each subblocks;
generate a residual block of the current block based on the prediction block; and
perform transform on the residual block,
wherein the processor is further configured to add 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 a width and a height of the current block is greater than or equal to a pre-defined size.
10. A non-transitory computer-readable medium for storing encoded picture information generated by the apparatus according to claim 5 .