Video encoding and decoding method and apparatus using selective subblock split information signaling
Disclosed is a video encoding/decoding method and an apparatus using selective transmission of subblock partitioning information. The video encoding/decoding method and apparatus selectively encode and decode the splitting direction of a subblock to reduce the overhead of signal transmission for using subblock partitioning while effectively performing intra prediction per subblock basis.
1. An intra prediction method for applying an intra prediction mode of a current block to subblocks obtained by splitting the current block performed by a video decoding apparatus, the method comprising:
decoding the size and an intra prediction mode of the current block;
generating a pre-prunable range of the subblocks based on the size of the current block and the number of partitioned subblocks, wherein the pre-prunable range includes a vertical pre-prunable range and a horizontal pre-prunable range and represents a set of intra prediction directions in which constructed samples of newly reconstructed neighboring subblocks are not used by the subblocks when prediction is performed; and
setting a splitting direction of the subblocks according to whether the intra prediction mode is included in the vertical pre-prunable range or the horizontal pre-prunable range.
2. The method of claim 1 , wherein generating the pre-prunable range comprises determining the number of the partitioned sub blocks according to the size of the current block or using the predecoded number of subblocks.
3. The method of claim 1 , wherein setting the splitting direction comprises setting the splitting direction of the subblocks to horizontal direction when the intra prediction mode is included in the vertical pre-prunable range.
4. The method of claim 1 , wherein setting the splitting direction comprises setting the splitting direction of the subblocks to vertical direction when the intra prediction mode is included in the horizontal pre-prunable range.
5. The method of claim 1 , wherein, when the intra prediction mode is not included in the pre-prunable range, setting the splitting direction comprises setting the splitting direction of the subblocks according to a subblock splitting direction flag after decoding the subblock splitting direction flag indicating the splitting direction of the sub blocks.
6. The method of claim 1 , wherein the vertical pre-prunable range includes values greater than a prediction direction corresponding to the top left diagonal line of subblocks partitioned in the vertical direction.
7. The method of claim 1 , wherein the horizontal pre-prunable range includes values smaller than a prediction direction corresponding to the top left diagonal line of subblocks partitioned in the horizontal direction.
8. An intra prediction method for applying an intra prediction mode of a current block to subblocks obtained by splitting the current block performed by a video encoding apparatus, the method comprising:
obtaining the size and an intra prediction mode of the current block;
generating a pre-prunable range of the subblocks based on the size of the current block, wherein the pre-prunable range includes a vertical pre-prunable range and a horizontal pre-prunable range and represents a set of intra prediction directions in which constructed samples of newly reconstructed neighboring subblocks are not used by the subblocks when prediction is performed; and
setting a splitting direction of the sub blocks according to whether the intra prediction mode is included in the vertical pre-prunable range or the horizontal pre-prunable range.
9. The method of claim 8 , wherein generating the pre-prunable range comprises determining the number of the partitioned sub blocks according to the size of the current block or using the number of sub blocks obtained previously.
10. The method of claim 8 , wherein, when the intra prediction mode is included in the vertical pre-prunable range, setting the splitting direction comprises setting the splitting direction of the subblock to horizontal direction and not generating a subblock splitting direction flag indicating a splitting direction of the subblocks.
11. The method of claim 8 , wherein, when the intra prediction mode is included in the horizontal pre-prunable range, setting the splitting direction comprises setting the splitting direction of the subblock to vertical direction and not generating a subblock splitting direction flag indicating a splitting direction of the sub blocks.
12. The method of claim 8 , wherein, when the intra prediction mode is not included in the pre-prunable range, setting the splitting direction comprises:
generating coding efficiency according to horizontal and vertical splitting of the current block; and
setting a subblock splitting direction indicating the splitting direction of the subblocks based on the coding efficiency.
13. A non-transitory computer-readable recording medium storing a bitstream generated by a video encoding method for applying an intra prediction mode of a current block to subblocks obtained by splitting the current block, wherein the method comprises:
obtaining the size and an intra prediction mode of the current block;
generating a pre-prunable range of the subblocks based on the size of the current block, wherein the pre-prunable range includes a vertical pre-prunable range and a horizontal pre-prunable range and represents a set of intra prediction directions in which constructed samples of newly reconstructed neighboring subblocks are not used by the subblocks when prediction is performed; and
setting a splitting direction of the subblocks according to whether the intra prediction mode is included in the vertical pre-prunable range or the horizontal pre-prunable range.