Intra-prediction apparatus, encoding apparatus, decoding apparatus and methods for non-square video coding blocks

1. A device, comprising:

a non-transitory computer-readable storage medium storing instructions; and

one or more processors in communication with the medium and, upon execution of the instructions, being configured to:

select a directional range from a set of directional ranges; and

determine a number of directional intra-prediction modes of the selected directional range according to a size of a block, wherein the block is a rectangular and non-square video coding block, the selected directional range comprises a basis directional range associated with a long side of the block, and further comprises an extension directional range that is associated with the long side of the block and that is dependent on an aspect ratio of the block, the extension directional range is outside of, and adjacent to the basis directional range along the long side of the block, and wherein the number of directional intra-prediction modes for the selected directional range comprises a number ΔM 0 of directional intra-prediction modes of the extension directional range, and wherein the number ΔM 0 of directional intra-prediction modes of the extension directional range is based on a lookup table having a plurality of numbers of directional intra-prediction modes for the extension directional range.

2. The device according to claim 1 , wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to determine the number of directional intra-prediction modes of the selected directional range according to the size of the block and the aspect ratio of the block.

3. The device according to claim 1 , wherein the one or more processors being configured to select the directional range comprises the processor being configured to select, from the set of directional ranges, a short directional range associated with a short side of the block and a long directional range associated with the long side of the block; and

wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to determine a number ΔMshort of directional intra-prediction modes of the short directional range and a number ΔMlong of directional intra-prediction modes of the long directional range according to:

Δ M long/ L long<Δ M short/ L short;

wherein Lshort is a length of the short side of the block, and Llong is a length of the long side of the block.

4. The device according to claim 1 , wherein the one or more processors being configured to select the directional range comprises the one or more processors being configured to select, from the set of directional ranges, a short directional range associated with a short side of the block, and a long directional range associated with the long side of the block; and

wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to determine a number ΔMshort of directional intra-prediction modes of the short directional range and a number ΔMlong of directional intra-prediction modes of the long directional range, wherein an angular resolution ARshort of the short directional range is higher than an angular resolution ARlong of the long directional range;

wherein an angular resolution ARG of a given directional range is proportional to a number ΔMG of directional intra-prediction modes of the given directional range, and is inversely proportional to an angle αG of the given directional range.

5. The device according to claim 4 , wherein the angular resolution ARG of the given directional range is defined by:

ARG=Δ MG/αG.

6. The device according to claim 4 , wherein two neighboring directional intra-prediction modes are at least one of two neighboring directional intra-prediction modes of the short directional range that are separated by a fixed angle β, or two neighboring directional intra-prediction modes of the long directional range that are separated by a fixed angle α.

7. The device according to claim 1 , wherein the basis directional range and the extension directional range are disjoint;

wherein the one or more processors being configured to select the directional range comprises the one or more processors being configured to select the extension directional range; and

wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to determine the number ΔM 0 of directional intra-prediction modes of the extension directional range according to a difference between a length L 0 /long of the long side of the block and a length L 0 /short of a short side of the block.

8. The device according to claim 1 , wherein the basis directional range and the extension directional range are disjoint

wherein the one or more processors being configured to select the directional range comprises the one or more processors being configured to select the extension directional range, and

wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to determine the number ΔM 0 of directional intra-prediction modes of the extension directional range.

9. The device according to claim 1 , wherein the one or more processors being configured to determine the number of directional intra-prediction modes comprises the one or more processors being configured to:

determine the number of directional intra-prediction modes of the selected directional range from the lookup table according to a block width and block height.

10. The device according to claim 1 , wherein the device is an encoding apparatus for encoding a rectangular and non-square video coding block; and

wherein the one or more processors, upon execution of the instructions, are further configured to:

provide a predicted video coding block; and

encode the video coding block into an encoded video bitstream according to of the predicted video coding block.

11. The device according to claim 1 , wherein the device is a decoding apparatus for decoding an encoded video bitstream;

wherein the one or more processors, upon execution of the instructions, are further configured to:

provide a predicted video coding block; and

restore the rectangular and non-square video coding block from the encoded video bitstream according to the predicted video coding block.

12. A method, comprising:

selecting a directional range from a set of directional ranges, and

determining a number of directional intra-prediction modes of the selected directional range according to a size of a block, wherein the block is a rectangular and non-square video coding block, the selected directional range comprises a basis directional range associated with a long side of the block, and further comprises an extension directional range that is associated with the long side of the block and that is dependent on an aspect ratio of the block, wherein the extension directional range is outside of, and adjacent to the basis directional range along the long side of the block, wherein the number of directional intra-prediction modes for the selected directional range comprises a number ΔM 0 of directional intra-prediction modes of the extension directional range, and wherein the number ΔM 0 of directional intra-prediction modes of the extension directional range is based on a lookup table having a plurality of numbers of directional intra-prediction modes for the extension directional range.

13. The method of claim 12 , wherein the determining the number of directional intra-prediction modes comprises determining the number of directional intra-prediction modes of the selected directional range according to the size of the block and the aspect ratio of the block.

14. The method of claim 12 , wherein the

wherein the selecting the directional range comprises selecting, from the set of directional ranges, a short directional range associated with a short side of the block and a long directional range associated with the long side of the block; and

wherein the determining the number of directional intra-prediction modes determining a number ΔMshort of directional intra-prediction modes of the short directional range and a number ΔMlong of directional intra-prediction modes of the long directional range according to:

Δ M long/ L long<Δ M short/ L short

wherein Lshort is a length of the short side of the block, and Llong is a length of the long side of the block.

15. The method of claim 12 , wherein the selecting the directional range comprises selecting, from the set of directional ranges, a short directional range associated with a short side of the block, and a long directional range associated with the long side of the block; and

wherein the determining the number of directional intra-prediction modes comprises determining a number ΔMshort of directional intra-prediction modes of the short directional range and a number ΔMlong of directional intra-prediction modes of the long directional range, wherein an angular resolution ARshort of the short directional range is higher than an angular resolution ARlong of the long directional range;

wherein an angular resolution ARG of a given directional range is proportional to a number ΔMG of directional intra-prediction modes of the given directional range, and is inversely proportional to an angle αG of the given directional range.

16. The method of claim 12 , wherein the extension directional range is dependent on the aspect ratio of the block; and

wherein the basis directional range and the extension directional range are disjoint.

17. The method of claim 12 , wherein the determining the number of directional intra-prediction modes comprises determining the number of directional intra-prediction modes of the selected directional range from the lookup table according to a block width and block height.

18. The method according to claim 12 , further comprising encoding the rectangular and non-square video coding block, the encoding the rectangular and non-square video coding block comprising

obtaining a predicted video coding block; and

encoding the video coding block into an encoded video bitstream according to the predicted video coding block.

19. The method according to claim 12 , further comprising decoding an encoded video bitstream, the decoding an encoded video bitstream comprising:

obtaining a predicted video coding block; and

restoring the rectangular and non-square video coding block from the encoded video bitstream according to the predicted video coding block.

20. A non-transitory computer readable medium having stored thereon instructions for execution by one or more processors, the instructions including instructions for:

selecting a directional range from a set of directional ranges, and

determining a number of directional intra-prediction modes of the selected directional range depending on a size of a block, wherein the block is a rectangular and non-square video coding block, the selected directional range comprises a basis directional range associated with a long side of the block, and further comprises an extension directional range that is associated with the long side of the block and that is dependent on an aspect ratio of the block, wherein the extension directional range is outside of, and adjacent to the basis directional range along the long side of the block, wherein the number of directional intra-prediction modes for the selected directional range comprises a number ΔM 0 of directional intra-prediction modes of the extension directional range, and wherein the number ΔM 0 of directional intra-prediction modes of the extension directional range is based on a lookup table having a plurality of numbers of directional intra-prediction modes for the extension directional range.