Method and apparatus for block partition with non-uniform quad split

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

acquiring a current picture from a coded video bitstream;

retrieving signaling information from the coded video bitstream for a block in the current picture;

determining, from the signaling information, whether the block is partitioned in accordance with a quad split partition type;

in response to determining that the block is not partitioned in accordance with the quad split partition type, determining whether the block is partitioned in accordance with a split partition type;

in response to determining that the block is partitioned in accordance with the split partition type, determining whether the block is partitioned in accordance with a non-uniform quad split partition type of a plurality of non-uniform partition types in which the block consists of four sub-blocks along a same direction; and

in response to determining that the block is partitioned in accordance with the non-uniform quad split partition type, reconstructing the block in accordance with the non-uniform quad split partition type of the plurality of non-uniform partition types,

wherein the block partitioned in accordance with the non-uniform quad partition split type includes first and second sub-blocks of a same fixed size, a third sub-block that is twice the fixed size, and a fourth sub-block that is four times the fixed size.

2. The method of according to claim 1 , wherein the determining whether the block is partitioned in accordance with the non-uniform quad split partition type further includes:

determining whether the block is partitioned in accordance with one of (i) a binary split partition type in which the block is partitioned into two sub-blocks along a same direction and (ii) a non-binary split partition type, and

in response to determining that the block is partitioned in accordance with the non-binary split partition type, determining whether the block is partitioned in accordance with one of (i) a ternary split partition type in which the block is partitioned into three sub-blocks along a same direction and (ii) the non-uniform quad split partition type.

3. The method according to claim 1 , wherein the determining whether the block is partitioned in accordance with the non-uniform quad split further includes:

determining whether the block is partitioned in accordance with (i) a non-quad split partition type, and (ii) the non-uniform quad split partition type.

4. The method of according to claim 3 , wherein in response to determining that the block is partitioned in accordance with the non-quad partition type, determining whether the block is partitioned in accordance with one of (i) a binary split partition type in which the block is partitioned into two sub-blocks along a same direction and (ii) a ternary split partition type in which the block is partitioned into three sub-blocks along a same direction.

5. The method according to claim 1 , wherein the first and second sub-blocks are adjacent to each other.

6. The method according to claim 1 , wherein the first and second sub-blocks are not adjacent to each other.

7. The method according to claim 1 , wherein the first sub-block is between the third sub-block and the fourth sub-block.

8. The method according to claim 1 , wherein the determining whether the block is partitioned in accordance with the non-uniform quad split partition type further includes:

determining a size of the block along an edge perpendicular to a direction in which the block is partitioned, and

in response to determining that the size of the block along the edge perpendicular to the direction in which the block is partitioned is greater than equal to 32 samples, determining that the block is partitioned in accordance with the non-uniform quad split partition type.

9. The method according to claim 1 , wherein the determining whether the block is partitioned in accordance with the non-uniform quad split partition type further includes:

in response to determining that a partition of the block in accordance with the non-uniform quad split partition type results in at least one sub-block being outside of a picture boundary of the current picture, determining that the block is not partitioned in accordance with the non-uniform quad split partition type.

10. A video decoder for video decoding, comprising:

processing circuitry to:

acquire a current picture from a coded video bitstream,

retrieve signaling information from the coded video bitstream for a block in the current picture,

determine, from the signaling information, whether the block is partitioned in accordance with a quad split partition type,

in response to the determination that the block is not partitioned in accordance with the quad split partition type, determine whether the block is partitioned in accordance with a split partition type,

in response to the determination that the block is partitioned in accordance with the split partition type, determine whether the block is partitioned in accordance with a non-uniform quad split partition type of a plurality of non-uniform partition types in which the block consists of four sub-blocks along a same direction, and

in response to the determination that the block is partitioned in accordance with the non-uniform quad split partition type, reconstruct the block in accordance with the non-uniform quad split partition type of the plurality of non-uniform partition types,

wherein the block partitioned in accordance with the non-uniform quad partition split type includes first and second sub-blocks of a same fixed size, a third sub-block that is twice the fixed size, and a fourth sub-block that is four times the fixed size.

11. The video decoder according to claim 10 , wherein the determination whether the block is partitioned in accordance with the non-uniform quad split partition type further includes the processing circuitry configured to:

determine whether the block is partitioned in accordance with one of (i) a binary split partition type in which the block is partitioned into two sub-blocks along a same direction and (ii) a non-binary split partition type, and

in response to the determination that the block is partitioned in accordance with the non-binary split partition type, determine whether the block is partitioned in accordance with one of (i) a ternary split partition type in which the block is partitioned into three sub-blocks along a same direction and (ii) the non-uniform quad split partition type.

12. The video decoder according to claim 10 , wherein the determination whether the block is partitioned in accordance with the non-uniform quad split further includes the processing circuitry configured to:

determine whether the block is partitioned in accordance with (i) a non-quad split partition type, and (ii) the non-uniform quad split partition type.

13. The video decoder according to claim 12 , wherein in response to the determination that the block is partitioned in accordance with the non-quad partition type, the processing circuitry is further configured to determine whether the block is partitioned in accordance with one of (i) a binary split partition type in which the block is partitioned into two sub-blocks along a same direction and (ii) a ternary split partition type in which the block is partitioned into three sub-blocks along a same direction.

14. The video decoder according to claim 10 , wherein the first and second sub-blocks are adjacent to each other.

15. The video decoder according to claim 10 , wherein the first and second sub-blocks are not adjacent to each other.

16. The video decoder according to claim 10 , wherein the determination whether the block is partitioned in accordance with the non-uniform quad split partition type further includes the processing circuitry configured to:

determine a size of the block along an edge perpendicular to a direction in which the block is partitioned, and

in response to the determination that the size of the block along the edge perpendicular to the direction in which the block is partitioned is greater than equal to 32 samples, determine that the block is partitioned in accordance with the non-uniform quad split partition type.

17. The video decoder according to claim 10 , wherein the determination whether the block is partitioned in accordance with the non-uniform quad split partition type further includes the processing circuitry further configured to:

in response to the determination that a partition of the block in accordance with the non-uniform quad split partition type results in at least one sub-block being outside of a picture boundary of the current picture, determine that the block is not partitioned in accordance with the non-uniform quad split partition type.

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

acquiring a current picture from a coded video bitstream;

retrieving signaling information from the coded video bitstream for a block in the current picture;

determining, from the signaling information, whether the block is partitioned in accordance with a quad split partition type;

in response to determining that the block is not partitioned in accordance with the quad split partition type, determining whether the block is partitioned in accordance with a split partition type;

in response to determining that the block is partitioned in accordance with the split partition type, determining whether the block is partitioned in accordance with a non-uniform quad split partition type of a plurality of non-uniform partition types in which the block consists of four sub-blocks along a same direction; and

in response to determining that the block is partitioned in accordance with the non-uniform quad split partition type, reconstructing the block in accordance with the non-uniform quad split partition type of the plurality of non-uniform partition types,

wherein the block partitioned in accordance with the non-uniform quad partition split type includes first and second sub-blocks of a same fixed size, a third sub-block that is twice the fixed size, and a fourth sub-block that is four times the fixed size.