Combined intra and inter prediction mode

1 . A method of video decoding performed at a computing system having memory and one or more processors, the method comprising:

receiving a video bitstream comprising a plurality of blocks including a first block, wherein the first block is encoded using a combined intra inter prediction (CIIP) mode;

identifying an intra prediction mode for the first block;

identifying an inter prediction mode for the first block, the identified inter prediction mode being one of:

a geometric partition-based inter prediction mode,

an affine motion based inter prediction mode, and

a temporal interpolation prediction mode; and

decoding the first block using the identified intra prediction mode and the identified inter prediction mode, wherein the inter prediction mode for the first block is selected from a group comprising the geometric partition-based inter prediction mode, the affine motion based inter prediction mode, and the temporal interpolation prediction mode when the identified intra prediction mode is one of a predefined set of intra prediction modes.

2 . The method of claim 1 , wherein decoding the first block using the identified intra prediction mode and the identified inter prediction mode comprises using a weighted combination of the identified intra prediction mode and the identified inter prediction mode, wherein the weighted combination uses a predefined set of weights.

3 . The method of claim 2 , wherein the predefined set of weights comprises a same weight applied to each sample of the first block.

4 . The method of claim 2 , wherein the predefined set of weights have reduced intra prediction weights according to an intra prediction angle.

5 . The method of claim 2 , wherein the predefined set of weights are identified based on at least one of the identified intra prediction mode and the identified inter prediction mode.

6 . The method of claim 1 , wherein:

the identified inter prediction mode is the geometric partition-based inter prediction mode using a wedge mask; and

decoding the first block using the identified intra prediction mode and the identified inter prediction mode comprises using the wedge mask to combine inter prediction samples and intra prediction samples.

7 . The method of claim 1 , wherein the predefined set of intra prediction modes consists of a smooth intra prediction mode and a direct current (DC) intra prediction mode.

8 . The method of claim 1 , wherein the predefined set of intra prediction modes consists of a smooth intra prediction mode, a direct current (DC) intra prediction mode, and a set of angular intra prediction modes.

9 . The method of claim 1 , wherein identifying the inter prediction mode comprises identifying a predefined warp motion mode as the affine motion based inter prediction mode.

10 . The method of claim 9 , wherein the video bitstream does not include warp model parameters for the first block.

11 . The method of claim 9 , wherein the predefined warp motion mode uses a warp model with warp model parameters from one or more neighboring blocks of the first block.

12 . The method of claim 9 , wherein the predefined warp motion mode is signaled in the video bitstream.

13 . The method of claim 9 , wherein the predefined warp motion mode is selected from a subset of allowed warp motion modes.

14 . The method of claim 1 , wherein the inter prediction mode is identified for the first block based on an indicator in the video bitstream.

15 . The method of claim 1 , further comprising applying a motion vector refinement to a motion vector of the identified inter prediction mode.

16 . The method of claim 15 , wherein applying the motion vector refinement comprises comparing inter prediction samples for the first block with intra prediction samples for the first block.

17 . The method of claim 15 , wherein the motion vector refinement is an optical flow based motion vector refinement.

18 . A computing system, comprising:

control circuitry;

memory; and

one or more sets of instructions stored in the memory and configured for execution by the control circuitry, the one or more sets of instructions comprising instructions for:

receiving video data comprising a plurality of blocks including a first block, wherein the first block is to be encoded using a combined intra inter prediction (CIIP) mode;

identifying an intra prediction mode for the first block;

identifying an inter prediction mode for the first block, the identified inter prediction mode being one of:

a geometric partition-based inter prediction mode,

an affine motion based inter prediction mode, and

a temporal interpolation prediction mode; and

encoding the first block using the identified intra prediction mode and the identified inter prediction mode, wherein the inter prediction mode for the first block is selected from a group comprising the geometric partition-based inter prediction mode, the affine motion based inter prediction mode, and the temporal interpolation prediction mode when the identified intra prediction mode is one of a predefined set of intra prediction modes.

19 . A non-transitory computer-readable storage medium storing a video encoding method, the video encoding method comprising:

receiving video data comprising a plurality of blocks including a first block, wherein the first block is to be encoded using a combined intra inter prediction (CIIP) mode;

identifying an intra prediction mode for the first block;

identifying an inter prediction mode for the first block, the identified inter prediction mode being one of:

a geometric partition-based inter prediction mode,

an affine motion based inter prediction mode, and

a temporal interpolation prediction mode; and

encoding the first block using the identified intra prediction mode and the identified inter prediction mode,

wherein the video bitstream comprises a signaled element indicating that the first block is to be encoded using a combined intra inter prediction (CIIP) mode such that the inter prediction mode for the first block is selected from a group comprising the geometric partition-based inter prediction mode, the affine motion-based inter prediction mode, and the temporal interpolation prediction mode when the identified intra prediction mode is one of a predefined set of intra prediction modes.