Method and apparatus for using an intra prediction coding tool for intra prediction of non-square blocks in video compression

1. A method for video decoding, comprising:

determining, for a current block that is a non-square block, that an angular intra prediction mode for the current block is a wide angle mode that is spaced apart from a vertical mode and a horizontal mode by an angular distance that is more than 45 degrees, the vertical mode aligned with a vertical axis of the current block, the horizontal mode aligned with a horizontal axis of the current block;

determining a non-wide angle mode that corresponds to the wide angle mode, the non-wide angle mode being spaced apart from the vertical mode or the horizontal mode by an angular distance that is less than or equal to 45 degrees;

accessing a look-up table (LUT) that specifies a coding tool for the determined non-wide angle mode; and

performing intra prediction for the current block by (i) retrieving at least one reference sample corresponding to the angular intra prediction mode that is the wide angle mode and (ii) using the retrieved at least one reference sample corresponding to the wide angle mode as an input into the coding tool specified in the LUT.

2. The method of claim 1 , wherein the corresponding non-wide angle mode is a non-wide angle mode that is 180 degrees from the wide angle mode.

3. The method of claim 1 , wherein the corresponding non-wide angle mode is a non-wide angle mode that is nearest to the wide angle mode.

4. The method of claim 3 , wherein the non-wide angle mode nearest to the wide angle mode is one of 2 and 66 based on an angle of the wide angle mode having a smallest distance to one of non-wide angle mode 2 and 66.

5. The method of claim 1 , wherein the coding tool specified in the LUT for the determined non-wide angle mode includes one or more prediction parameters associated with the coding tool.

6. The method according to claim 1 , wherein the coding tool is Position Dependent Prediction Combination (PDPC).

7. The method according to claim 1 , further comprising:

performing an inverse transform for the current block using a Non Separable Secondary Transform (NSST) that is specified for the determined corresponding non-wide angle mode.

8. A video decoder for video decoding, comprising:

processing circuitry configured to:

determine, for a current block that is a non-square block, that an angular intra prediction mode for the current block is a wide angle mode that is spaced apart from a vertical mode and a horizontal mode by an angular distance that is more than 45 degrees, the vertical mode aligned with a vertical axis of the current block, the horizontal mode aligned with a horizontal axis of the current block,

determine a non-wide angle mode that corresponds to the wide angle mode, the non-wide angle mode being spaced apart from the vertical mode or the horizontal mode by an angular distance that is less than or equal to 45 degrees,

access to a look-up table (LUT) that specifies a coding tool for the determined non-wide angle mode, and

perform intra prediction for the current block by (i) retrieving at least one reference sample corresponding to the angular intra prediction mode that is the wide angle mode and (ii) using the retrieved at least one reference sample corresponding to the wide angle mode as an input into the coding tool specified in the LUT.

9. The video decoder of claim 8 , wherein the corresponding non-wide angle mode is a non-wide angle mode that is 180 degrees from the wide angle mode.

10. The video decoder of claim 8 , wherein the corresponding non-wide angle mode is a non-wide angle mode that is nearest to the wide angle mode.

11. The video decoder of claim 10 , wherein the non-wide angle mode nearest to the wide angle mode is one of 2 and 66 based on an angle of the wide angle mode having a smallest distance to one of non-wide angle mode 2 and 66.

12. The video decoder of claim 8 , wherein the coding tool specified in the LUT for the determined non-wide angle mode further includes one or more prediction parameters associated with the coding tool.

13. The video decoder of claim 8 , wherein the coding tool is Position Dependent Prediction Combination (PDPC).

14. The video decoder of claim 8 , wherein the processing circuitry is further configured to perform an inverse transform for the current block, using a Non Separable Secondary Transfoi (NSST) that is specified for the determined corresponding non-wide angle mode.

15. A non-transitory computer readable medium having instructions stored therein, which when executed by a processor in a video decoder causes the processor to execute a method comprising:

determining, for a current block that is a non-square block, an angular intra prediction mode for the current block is a wide angle mode that is spaced apart from a vertical mode and a horizontal mode by an angular distance that is more than 45 degrees, the vertical mode aligned with a vertical axis of the current block, the horizontal mode aligned with a horizontal axis of the current block;

determining a non-wide angle mode that corresponds to the wide angle mode, the non-wide angle mode being spaced apart from the vertical mode or the horizontal mode by an angular distance that is less than or equal to 45 degrees;

accessing a look-up table (LUT) that specifies a coding tool for the determined non-wide angle mode; and

performing intra prediction for the current block by retrieving (i) at least one reference sample corresponding to the angular intra prediction mode that is the wide angle mode and (ii) using the retrieved at least one reference sample corresponding to the wide angle mode as an input into the coding tool specified in the LUT.

16. The non-transitory computer readable medium of claim 15 , wherein the corresponding non-wide angle mode is a non-wide angle mode that is 180 degrees from the wide angle mode.