Intra block copy buffer and palette predictor update
Methods and apparatus for video processing are described. One example method includes determining, for a conversion between a video block of a video and a bitstream of the video, that the video block satisfies a condition. The video block is coded in the bitstream using an intra block copy mode. The method further includes performing the conversion based on the determining. Here, due to the video block satisfying the condition, a portion of an intra block copy buffer is reset during the conversion.
1. A method of processing video data, comprising:
determining, for a conversion between a video block of a video picture of a video and a bitstream of the video, that a first prediction mode is applied to the video block;
maintaining, for the first prediction mode, a virtual buffer comprising reference samples derived from the video picture, wherein in the first prediction mode, prediction samples of the video block are derived from the reference samples in the virtual buffer as determined by a block vector; and
performing the conversion based on the determining,
wherein the reference samples in a first region of the virtual buffer are set to be −1 and are unavailable for deriving the prediction samples,
wherein the first region maps to a second region of the video picture, and
wherein when a width of the video block is greater than a size of a virtual unit, a width of the second region is equal to the width of the video block, and when a width of the video block is less than a size of a virtual unit, a width of the second region is equal to a width of the virtual unit.
2. The method of claim 1 , wherein when a height of the video block is greater than a size of a virtual unit, a height of the second region is equal to the height of the video block.
3. The method of claim 1 , wherein an upper-left corner of the second region is an upper-left corner of the virtual unit.
4. The method of claim 1 , wherein when a height of the video block is less than a size of a virtual unit, a height of the second region is equal to a height of the virtual unit.
5. The method of claim 1 , wherein a location of (x, y) in the second region is mapped to a location of (((x+(IbcBufWidthY>>1))% IbcBufWidthY), (y % CtbSizeY)) in the first region.
6. The method of claim 1 , wherein the conversion includes encoding the video block into the bitstream.
7. The method of claim 1 , wherein the conversion comprises decoding the video from the bitstream.
8. An apparatus for processing video data comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to:
determine, for a conversion between a video block of a video picture of a video and a bitstream of the video, that a first prediction mode is applied to the video block;
maintain, for the first prediction mode, a virtual buffer comprising reference samples derived from the video picture, wherein in the first prediction mode, prediction samples of the video block are derived from the reference samples in the virtual buffer as determined by a block vector; and
perform the conversion based on the determination,
wherein the reference samples in a first region of the virtual buffer are set to be −1 and are unavailable for deriving the prediction samples,
wherein the first region maps to a second region of the video picture,
wherein when a width of the video block is greater than a size of a virtual unit, a width of the second region is equal to the width of the video block, and when a width of the video block is less than a size of a virtual unit, a width of the second region is equal to a width of the virtual unit.
9. The apparatus of claim 8 , wherein when a height of the video block is greater than a size of a virtual unit, a height of the second region is equal to the height of the video block.
10. The apparatus of claim 8 , wherein an upper-left corner of the second region is an upper-left corner of the virtual unit.
11. The apparatus of claim 8 , wherein when a height of the video block is less than a size of a virtual unit, a height of the second region is equal to a height of the virtual unit.
12. The apparatus of claim 8 , wherein a location of (x, y) in the second region is mapped to a location of (((x+(IbcBufWidthY>>1))% IbcBufWidthY), (y % CtbSizeY)) in the first region.
13. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
determine, for a conversion between a video block of a video picture of a video and a bitstream of the video, that a first prediction mode is applied to the video block;
maintain, for the first prediction mode, a virtual buffer comprising reference samples derived from the video picture, wherein in the first prediction mode, prediction samples of the video block are derived from the reference samples in the virtual buffer as determined by a block vector; and
perform the conversion based on the determination,
wherein the reference samples in a first region of the virtual buffer are set to be −1 and are unavailable for deriving the prediction samples,
wherein the first region maps to a second region of the video picture,
wherein when a width of the video block is greater than a size of a virtual unit, a width of the second region is equal to the width of the video block, and when a width of the video block is less than a size of a virtual unit, a width of the second region is equal to a width of the virtual unit.
14. The non-transitory computer-readable storage medium of claim 13 , wherein when a height of the video block is greater than a size of a virtual unit, a height of the second region is equal to the height of the video block.
15. The non-transitory computer-readable storage medium of claim 13 , wherein an upper-left corner of the second region is an upper-left corner of the virtual unit.
16. The non-transitory computer-readable storage medium of claim 13 ,
wherein when a height of the video block is less than a size of a virtual unit, a height of the second region is equal to a height of the virtual unit.
17. The non-transitory computer-readable storage medium of claim 13 , wherein a location of (x, y) in the second region is mapped to a location of (((x+(IbcBufWidthY>>1))% IbcBufWidthY), (y % CtbSize Y)) in the first region.
18. A non-transitory computer-readable recording medium storing a bitstream of a video which is generated by a method performed by a video processing apparatus, wherein the method comprises:
determining, for a video block of a video picture of the video, that a first prediction mode is applied to the video block;
maintaining, for the first prediction mode, a virtual buffer comprising reference samples derived from the video picture, wherein in the first prediction mode, prediction samples of the video block are derived from the reference samples in the virtual buffer as determined by a block vector; and
generating the bitstream based on the determining,
wherein the reference samples in a first region of the virtual buffer are set to be −1 and are unavailable for deriving the prediction samples,
wherein the first region maps to a second region of the video picture,
wherein when a width of the video block is greater than a size of a virtual unit, a width of the second region is equal to the width of the video block, and when a width of the video block is less than a size of a virtual unit, a width of the second region is equal to a width of the virtual unit.
19. The non-transitory computer-readable recording medium of claim 18 , wherein when a height of the video block is greater than a size of a virtual unit, a height of the second region is equal to the height of the video block,
wherein an upper-left corner of the second region is an upper-left corner of the virtual unit,
wherein when a height of the video block is less than a size of a virtual unit, a height of the second region is equal to a height of the virtual unit, and
wherein a location of (x, y) in the second region is mapped to a location of (((x+(IbcBufWidthY>>1))% IbcBufWidthY), (y % CtbSize Y)) in the first region.