Method and apparatus for video coding

1. A method for video decoding in a decoder, comprising:

decoding prediction information of a current block in a picture from a coded video bitstream;

retrieving an intra block copy (IBC) enable flag from the decoded prediction information;

determining an IBC prediction mode usage flag for the current block based on (i) the IBC enable flag and (ii) a type of a tile group or slice to which the current block belongs;

determining, based on the IBC prediction mode usage flag, an IBC prediction mode that is separate from an inter prediction mode and an intra prediction mode;

determining, a block vector that points to a reference area in the picture in response to the determination of the IBC prediction mode; and

reconstructing the current block based on reference samples within the reference area in the picture.

2. The method of claim 1 , wherein

the IBC prediction mode usage flag is determined to indicate the IBC prediction mode when the IBC enable flag is indicative of enabling, the tile group or slice is I type, and the current block satisfies a size requirement.

3. The method of claim 1 , wherein when the tile group or slice type is I type, the current block satisfies a size constraint, and the IBC prediction mode usage flag is not signaled in the coded video bitstream,

a value of the IBC prediction mode usage flag is determined according to the IBC enable flag.

4. The method of claim 1 , wherein when the tile group or slice type is B or P type, the current block satisfies a size constraint, and the IBC prediction mode usage flag is not signaled in the coded video bitstream,

the IBC prediction mode usage flag is determined to be 0.

5. The method of claim 1 , wherein the IBC enable flag is a parameter of at least one of a video level, a sequence level, a picture level, and a tile group or slice level.

6. The method of claim 1 , further comprising at least one of:

decoding, from the coded video bitstream, a prediction mode flag; and

determining the prediction mode flag based on a skip flag and the type of the tile group or slice to which the current block belongs.

7. The method of claim 1 , further comprising:

determining, based on the decoded prediction information, a prediction mode flag, and the IBC prediction mode usage flag; and

selecting a prediction mode from the IBC prediction mode, the intra prediction mode and the inter prediction mode based on a combination of the prediction mode flag and the IBC prediction mode usage flag.

8. The method of claim 1 , wherein

the determining the IBC prediction mode for the current block is performed when the current block satisfies a size requirement.

9. An apparatus for video decoding, comprising:

processing circuitry configured to:

decode prediction information of a current block in a picture from a coded video bitstream,

retrieve an intra block copy (IBC) enable flag from the decoded prediction information,

determine an IBC prediction mode usage flag for the current block based on (i) the IBC enable flag and (ii) a type of a tile group or slice to which the current block belongs,

determine, based on the IBC prediction mode usage flag, an IBC prediction mode that is separate from an inter prediction mode and an intra prediction mode,

determine, a block vector that points to a reference area in the picture in response to the determination of the IBC prediction rode, and

reconstruct the current block based on reference samples within the reference area in the picture.

10. The apparatus of claim 9 , wherein

the IBC prediction mode usage flag is determined to indicate the IBC prediction mode when the IBC enable flag is indicative of enabling, the tile group or slice type is I type, and the current block satisfies a size requirement.

11. The apparatus of claim 9 , wherein when the tile group or slice type is I type, the current block satisfies a size constraint, and the IBC prediction mode usage flag is not signaled in the coded video bitstream,

a value of the IBC prediction mode usage flag is determined according to the IBC enable flag.

12. The apparatus of claim 9 , wherein the IBC enable flag is a parameter of at least one of a video level, a sequence level, a picture level, and a tile group level.

13. The apparatus of claim 9 , wherein the processing circuitry is configured to:

decode, from the coded video bitstream, a prediction mode flag, or

determine the prediction mode flag based on a skip flag and the type of the tile group or slice to which that the current block belongs.

14. The apparatus of claim 9 , wherein the processing circuitry is configured to:

determine, based on the decoded prediction information, a prediction mode flag, and the IBC prediction mode usage flag, and

select a prediction mode from the IBC prediction mode, the intra prediction mode and the inter prediction mode based on a combination of the prediction mode flag and the IBC prediction mode usage flag.

15. The apparatus of claim 9 , wherein

the IBC prediction mode for the current block is determined when the current block satisfies a size requirement.

16. A non-transitory computer-readable medium storing instructions which when executed by a computer for video decoding cause the computer to perform:

decoding prediction information of a current block in a picture from a coded video bitstream;

retrieving an intra block copy (IBC) enable flag from the decoded prediction information;

determining an IBC prediction mode usage flag for the current block based on (i) the IBC enable flag and (ii) a type of a tile group or slice to which the current block belongs;

determining, based on the IBC prediction mode usage flag, an IBC prediction mode that is separate from an inter prediction mode and an intra prediction mode;

determining, a block vector that points to a reference area in the picture in response to the determination of the IBC prediction mode; and

reconstructing the current block based on reference samples within the reference area in the picture.