Method and apparatus for block vector prediction with integer offsets in intra picture block compensation

1. A method of video decoding performed by a video decoder, the method comprising:

receiving a coded video bitstream containing a current picture;

determining whether a current block in the current picture is coded in intra block copy (IBC) mode;

in response to a determination that the current block is coded in the IBC mode, determining whether a mode with a motion vector offset is enabled for the IBC encoded current block; and

in response to a determination that the mode with the motion vector offset is enabled for the IBC encoded current block, decoding the current block in accordance with an offset associated with the current block,

wherein fractional offsets are not permitted for the IBC encoded current block irrespective of whether a first flag that indicates whether fractional offsets are permitted for the mode with the motion vector offset (i) is signaled in the coded video bitstream and (ii) is a value permitting fractional offsets, and

wherein, in response to a determination that the motion vector offset is a fractional offset, the motion vector offset is left shifted such that the motion vector offset is converted from the fractional offset to an integer offset.

2. The method according to claim 1 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block.

3. The method according to claim 1 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block in response to a determination that a third flag indicates that the mode with vector offset is enabled for the current block.

4. The method according to claim 3 , wherein in response to the determination that the third flag indicates that the mode with the motion vector offset is enabled for the current block, the first flag that indicates whether fractional offsets are permitted is set to false irrespective of whether the first flag (i) is signaled in the coded video bitstream and (ii) is the value permitting fractional offsets.

5. The method according to claim 4 , wherein in response to a determination that one of (i) the third flag and the (ii) second flag is false, the first flag that indicates whether fractional offsets is enabled is signaled in the coded video bitstream.

6. The method according to claim 1 , wherein in response to the determination that the mode with motion vector offset is enabled for the IBC encoded current block, the offset is selected from a table that specifies a plurality of offset distances each of which is a power of 2.

7. A video decoder for video decoding, comprising:

processing circuitry configured to:

receive a coded video bitstream containing a current picture,

determine whether a current block in the current picture is coded in intra block copy (IBC) mode,

in response to a determination that the current block is coded in the IBC mode, determine whether a mode with a motion vector offset is enabled for the IBC encoded current block, and

in response to a determination that the mode with the motion vector offset is enabled for the IBC encoded current block, decode the current block in accordance with an offset associated with the current block,

wherein fractional offsets are not permitted for the IBC encoded current block irrespective of whether a first flag that indicates whether fractional offsets are permitted for the mode with the motion vector offset (i) is signaled in the coded video bitstream and (ii) is a value permitting fractional offsets, and

wherein, in response to a determination that the motion vector offset is a fractional offset, the motion vector offset is left shifted such that the motion vector offset is converted from the fractional offset to an integer offset.

8. The video decoder according to claim 7 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block.

9. The video decoder according to claim 8 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block in response to a determination that a third flag indicates that the mode with vector offset is enabled for the current block.

10. The video decoder according to claim 9 , wherein in response to the determination that the third flag indicates that the mode with the motion vector offset is enabled for the current block, the first flag that indicates whether fractional offsets are permitted is set to false irrespective of whether the first flag (i) is signaled in the coded video bitstream and (ii) is the value permitting fractional offsets.

11. The video decoder according to claim 10 , wherein in response to a determination that one of (i) the third flag and the (ii) second flag is false, the first flag that indicates whether fractional offsets is enabled is signaled in the coded video bitstream.

12. The video decoder according to claim 7 , wherein in response to the determination that the mode with motion vector offset is enabled for the IBC encoded current block, the offset is selected from a table that specifies a plurality of offset distances each of which is a power of 2.

13. A non-transitory computer readable medium having instructions stored therein, which when executed by a processor in method of video decoding performed by a video decoder, the method comprising:

receiving a coded video bitstream containing a current picture;

determining whether a current block in the current picture is coded in intra block copy (IBC) mode;

in response to a determination that the current block is coded in the IBC mode, determining whether a mode with a motion vector offset is enabled for the IBC encoded current block; and

in response to a determination that the mode with the motion vector offset is enabled for the IBC encoded current block, decoding the current block in accordance with an offset associated with the current block,

wherein fractional offsets are not permitted for the IBC encoded current block irrespective of whether a first flag that indicates whether fractional offsets are permitted for the mode with the motion vector offset (i) is signaled in the coded video bitstream and (ii) is a value permitting fractional offsets, and

wherein, in response to a determination that the motion vector offset is a fractional offset, the motion vector offset is left shifted such that the motion vector offset is converted from the fractional offset to an integer offset.

14. The non-transitory computer readable medium according to claim 13 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block.

15. The non-transitory computer readable medium according to claim 13 , wherein the determination that the current block is coded in the IBC mode is based on a second flag that indicates that the IBC mode is enabled for the current block, and

wherein in response to the determination that the second flag indicates that the IBC mode is enabled for the current block, the mode with the motion vector offset is determined to be enabled for the current block in response to a determination that a third flag indicates that the mode with vector offset is enabled for the current block.

16. The non-transitory computer readable medium according to claim 15 , wherein in response to the determination that the third flag indicates that the mode with the motion vector offset is enabled for the current block, the first flag that indicates whether fractional offsets are permitted is set to false irrespective of whether the first flag (i) is signaled in the coded video bitstream and (ii) is the value permitting fractional offsets.

17. The non-transitory computer readable medium according to claim 16 , wherein in response to a determination that one of (i) the third flag and the (ii) second flag is false, the first flag that indicates whether fractional offsets is enabled is signaled in the coded video bitstream.