Context for coding affine mode adaptive motion vector resolution

1. A method for video processing, comprising:

determining, for a conversion between a current video block of a video and a bitstream of the video, at least one syntax element of which at least one bin is context-coded for the current video block;

determining a context increasement value for the at least one bin;

determining a variable for the context increasement value; and

performing the conversion at least based on the variable;

wherein the variable controls two probability updating speeds for context.

2. The method of claim 1 , wherein the at least one syntax element in the bitstream is used to indicate a motion precision in a motion precision set; and

wherein the context is selected from multiple contexts for the at least one syntax element based on a coding mode of the current video block.

3. The method of claim 2 , wherein multiple syntax elements are selectively presented in the bitstream to indicate the motion precision in the motion precision set, wherein the multiple syntax elements include a first syntax element and a second syntax element, wherein the second syntax element is present in the bitstream in case that the first syntax element is present in the bitstream with a specific value; and

wherein the at least one syntax element comprises the first syntax element and/or the second syntax element.

4. The method of claim 2 , wherein the context increasement value is selected from multiple context increasement values based on whether the coding mode of the current video block is a first mode, and wherein in the first mode, control point motion vectors are derived and further used to derive motion vectors of sub-region split from the current video block.

5. The method of claim 1 , wherein the context increasement value is selected without using coding information of a neighboring video block of the current video block, and the coding information of the neighboring video block comprises a coding mode of the neighboring video block.

6. The method of claim 1 , wherein the two probability updating speeds include a first updating speed defined by (shiftIdx>>2)+2, shiftIdx indicating the variable.

7. The method of claim 1 , wherein the two probability updating speeds include a second updating speed defined by (shiftIdx & 3)+3+shift0, shift0 indicating a first updating speed and shiftIdx indicating the variable.

8. The method of claim 7 , wherein the first updating speed is greater than or equal to 2.

9. The method of claim 7 , wherein the first updating speed is smaller than or equal to 5.

10. The method of claim 3 , wherein the second syntax element indicates a selection from 1-pel, ½-pel, or 4-pel precision for a normal inter mode, and the second syntax element indicates a selection from 1/16-pel or 1-pel precision for a first mode, and wherein in the first mode, control point motion vectors are derived and further used to derive motion vectors of sub-region split from the current video block.

11. The method of claim 3 , wherein the second syntax element is equal to 0, and the motion precision is 1/16-pel precision for a first mode, and wherein the second syntax element is equal to 1, and the motion precision is 1-pel precision for a first mode, and wherein in the first mode, control point motion vectors are derived and further used to derive motion vectors of sub-region split from the current video block.

12. The method of claim 1 , wherein the performing of the conversion includes generating the bitstream based on the current video block.

13. The method of claim 1 , wherein the performing of the conversion includes generating the current video block from the bitstream.

14. 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 current video block of a video and a bitstream of the video, at least one syntax element of which at least one bin is context-coded for the current video block;

determine a context increasement value for the at least one bin;

determine a variable for the context increasement value; and

perform the conversion at least based on the variable;

wherein the variable controls two probability updating speeds for the context.

15. The apparatus of claim 14 , wherein the two probability updating speeds include a first updating speed defined by (shiftIdx>>2)+2, shiftIdx indicating the variable.

16. The apparatus of claim 14 , wherein the two probability updating speeds include a second updating speed defined by (shiftIdx & 3)+3+shift0, shift0 indicating a first updating speed and shiftIdx indicating the variable.

17. The apparatus of claim 15 , wherein the first updating speed is greater than or equal to 2.

18. The apparatus of claim 15 , wherein the first updating speed is smaller than or equal to 5.

19. 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, at least one syntax element of which at least one bin is context-coded for the current video block;

determine a context increasement value for the at least one bin;

determine a variable for the context increasement value; and

perform the conversion at least based on the variable;

wherein the variable controls two probability updating speeds for context.

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, at least one syntax element of which at least one bin is context-coded;

determining a context increasement value for the at least one bin;

determining a variable for the context increasement value; and

generating the bitstream at least based on the variable;

wherein the variable controls two probability updating speeds for context.