Interaction between IBC and affine
Devices, systems and methods for applying intra-block copy (IBC) in video coding are described. In general, methods for integrating IBC with existing motion compensation algorithms for video encoding and decoding are described. In a representative aspect, a method for video encoding using IBC includes determining whether a current block of the current picture is to be encoded using a motion compensation algorithm, and encoding, based on the determining, the current block by selectively applying an intra-block copy to the current block. In a representative aspect, another method for video encoding using IBC includes determining whether a current block of the current picture is to be encoded using an intra-block copy, and encoding, based on the determining, the current block by selectively applying a motion compensation algorithm to the current block.
1. A method of processing video data, comprising:
determining, for a conversion between a current video block of a video and a bitstream of the video, that the current video block is coded with a first technique;
deriving control point motion information for the current video block;
deriving sample motion information for a sample of the current video block based on the control point motion information;
performing the conversion based on the sample motion information;
wherein the sample motion information includes reference picture information of one or more reference pictures, and wherein at least one of the reference pictures is different from a current picture including the current video block, and
wherein the control point motion information is derived based on a motion vector difference and a motion candidate list, and a motion candidate in the motion candidate list has at least one reference picture that is same as the current picture.
2. The method of claim 1 , wherein, in response to a bi-directional prediction mode is used in the first technique, one reference picture is different from the current picture and other reference picture is the same as the current picture.
3. The method of claim 1 , wherein, in response to a bi-directional prediction mode is used in the first technique, both reference pictures are different from the current picture.
4. The method of claim 1 , wherein, in the derivation of the sample motion information, a motion vector offset is derived for both horizontal direction and vertical direction based on the control point motion information and a size of the current video block.
5. The method of claim 4 , wherein the sample motion information is derived based on the motion vector offset and a location of the sample.
6. The method of claim 4 , wherein a height and width of the current video block are both larger than or equal to 16.
7. The method of claim 3 , wherein both reference pictures are marked as a long-term reference picture.
8. The method of claim 1 , wherein the conversion generates the current video block from the bitstream.
9. The method of claim 1 , wherein the conversion generates the bitstream from the current video block.
10. An apparatus for coding 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 current video block of a video and a bitstream of the video, that the current video block is coded with a first technique;
derive control point motion information for the current video block;
derive sample motion information for a sample of the current video block based on the control point motion information;
perform the conversion based on the sample motion information;
wherein the sample motion information includes reference picture information of one or more reference pictures, and wherein at least one of the reference pictures is different from a current picture including the current video block, and
wherein the control point motion information is derived based on a motion vector difference and a motion candidate list, and a motion candidate in the motion candidate list has at least one reference picture that is same as the current picture.
11. The apparatus of claim 10 , wherein, in response to a bi-directional prediction mode is used in the first technique, one reference picture is different from the current picture and other reference picture is the same as the current picture.
12. The apparatus of claim 10 , wherein, in response to a bi-directional prediction mode is used in the first technique, both reference pictures are different from the current picture.
13. The apparatus of claim 10 , wherein, in the derivation of the sample motion information, a motion vector offset is derived for both horizontal direction and vertical direction based on the control point motion information and a size of the current video block.
14. The apparatus of claim 13 , wherein the sample motion information is derived based on the motion vector offset and a location of the sample.
15. The apparatus of claim 13 , wherein a height and width of the current video block are both larger than or equal to 16.
16. The apparatus of claim 12 , wherein both reference pictures are marked as a long-term reference picture.
17. A non-transitory computer-readable storage medium storing instructions that cause a processor to:
determine, for a conversion between a current video block of a video and a bitstream of the video, that the current video block is coded with a first technique;
derive control point motion information for the current video block;
derive sample motion information for a sample of the current video block based on the control point motion information;
perform the conversion based on the sample motion information;
wherein the sample motion information includes reference picture information of one or more reference pictures, and wherein at least one of the reference pictures is different from a current picture including the current video block, and
wherein the control point motion information is derived based on a motion vector difference and a motion candidate list, and a motion candidate in the motion candidate list has at least one reference picture that is same as the current picture.
18. The non-transitory computer-readable storage medium of claim 17 , wherein in response to a bi-directional prediction mode is used in the first technique, one reference picture is different from the current picture and other reference picture is the same as the current picture.
19. The non-transitory computer-readable storage medium of claim 17 , wherein in response to a bi-directional prediction mode is used in the first technique, both reference pictures are different from the current picture.
20. 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 current video block of the video, that the current video block is coded with a first technique;
deriving control point motion information for the current video block;
deriving sample motion information for a sample of the current video block based on the control point motion information; and
generating the bitstream based on the sample motion information;
wherein the sample motion information includes reference picture information of one or more reference pictures, and wherein at least one of the reference pictures is different from a current picture including the current video block, and
wherein the control point motion information is derived based on a motion vector difference and a motion candidate list, and a motion candidate in the motion candidate list has at least one reference picture that is same as the current picture.