Method for video coding using various block partitioning structures

1 . A video decoding apparatus for partitioning a current block, the video decoding apparatus configured to:

decode, from a bitstream, a split flag indicating whether the current block is to be partitioned using one of a plurality of a quad-tree split, a binary-tree split, and a ternary-tree split;

determine a width and a height of the current block;

calculate an aspect ratio of the current block from the width and the height of the current block, the aspect ratio being a ratio obtained by dividing the width of the current block by the height of the current block; and

check for a value of the split flag,

wherein if the split flag is true, the video decoding apparatus is further configured to:

decode one or more additional syntax elements to determine which one of the plurality of the quad-tree split, the binary-tree split, and the ternary-tree split is used to partition the current block; and

partition the current block according to the additional syntax elements,

wherein if the split flag is false, the video decoding apparatus is further configured to:

check whether the aspect ratio satisfies a preset first condition and whether the width and the height satisfy a preset second condition;

if the aspect ratio satisfies the first condition and if the width and the height satisfy the second condition, decode from the bitstream a sequential split flag indicating whether the current block is to be partitioned using a sequential quad-tree structure; and

if the sequential split flag is true, partition the current block into lower blocks by using the sequential quad-tree structure.

2 . The video decoding apparatus of claim 1 , further configured to, when the split flag is false:

determine that the current block is a leaf node which is not split any further without decoding the sequential split flag, if the aspect ratio does not satisfy the first condition or if the width and the height do not satisfy the second condition.

3 . The video decoding apparatus of claim 1 , wherein the first condition is that the aspect ratio is 4:1 or 1:4.

4 . The video decoding apparatus of claim 1 , wherein the second condition is that a smaller value between the width and the height is greater than or equal to a preset minimum block unit size.

5 . The video decoding apparatus of claim 1 , further configured to:

based on the aspect ratio, partition the current block vertically into four sequential square lower blocks or partition the current block horizontally into four sequential square lower blocks, wherein the lower blocks are equal in size.

6 . The video decoding apparatus of claim 1 , wherein the lower blocks comprise:

leaf nodes that involve no further block partitioning.

7 . The video decoding apparatus of claim 1 , wherein the lower blocks comprise:

blocks when vertically partitioned, to be sequentially decoded in a left-to-right direction.

8 . The video decoding apparatus of claim 1 , wherein the lower blocks comprise:

blocks when horizontally partitioned, to be sequentially decoded in a top-to-bottom direction.

9 . The video decoding apparatus of claim 1 , further configured to:

decode a coding order flag indicating a coding order,

wherein the lower blocks comprise:

blocks when vertically partitioned, to be sequentially decoded in a left-to-right direction or a right-to-left direction depending on a value of the coding order flag.

10 . The video decoding apparatus of claim 1 , further configured to:

decode a coding order flag indicating a coding order,

wherein the lower blocks comprise:

blocks when horizontally partitioned, to be sequentially decoded in a top-to-bottom direction or a bottom-to-top direction depending on the value of the coding order flag.

11 . The video decoding apparatus of claim 1 , further configured to:

determine that the current block is a leaf node which is not split any further, if the sequential split flag is false.

12 . A video encoding apparatus for partitioning a current block, the video encoding apparatus configured to:

determine a width and a height of the current block;

encode a split flag indicating whether the current block is to be partitioned using one of a plurality of a quad-tree split, a binary-tree split, and a ternary-tree split;

calculate an aspect ratio of the current block from the width and the height of the current block, the aspect ratio being a ratio obtained by dividing the width of the current block by the height of the current block; and

check for a value of the split flag,

wherein if the split flag is true, the video encoding apparatus further configured to:

encode one or more additional syntax elements to indicate which one of the plurality of the quad-tree split, the binary-tree split, and the ternary-tree split is used to partition the current block; and

partition the current block according to the additional syntax elements,

wherein if the split flag is false, the video encoding apparatus is further configured to:

check whether the aspect ratio satisfies a preset first condition and whether the width and the height satisfy a preset second condition;

if the aspect ratio satisfies the first condition and if the width and the height satisfy the second condition, encode a sequential split flag whether the current block is to be partitioned using a sequential quad-tree structure; and

if the sequential split flag is true, partition the current block into lower blocks by using the sequential quad-tree structure.

13 . The video encoding apparatus of claim 12 , further configured to, if the split flag is false:

determine the current block to be a leaf node if the aspect ratio does not satisfy the first condition or if the width and the height do not satisfy the second condition.

14 . The video encoding apparatus of claim 12 , further configured to:

determine that the current block is a leaf node which is not split any further, if the sequential split flag is false.

15 . An apparatus for providing a video decoding apparatus with video data, the apparatus configured to:

encode the video data into a bitstream; and

transmit the bitstream to the video decoding apparatus,

wherein in encoding the video data, the apparatus is further configured to:

determine a width and a height of a current block;

encode a split flag indicating whether the current block is to be partitioned using one of a plurality of a quad-tree split, a binary-tree split, and a ternary-tree split;

calculate an aspect ratio of the current block from the width and the height, the aspect ratio being a ratio obtained by dividing the width of the current block by the height of the current block;

check for a value of the split flag,

wherein if the split flag is true, the apparatus is further configured to:

encode one or more additional syntax elements to indicate which one of the plurality of the quad-tree split, the binary-tree split, and the ternary-tree split is used to partition the current block; and

partition the current block according to the additional syntax elements,

wherein if the split flag is false, the apparatus is further configured to:

check whether the aspect ratio satisfies a preset first condition and whether the width and the height satisfy a preset second condition;

if the aspect ratio satisfies the first condition and if the width and the height satisfy the second condition, encode a sequential split flag whether the current block is to be partitioned using a sequential quad-tree structure; and

if the sequential split flag is true, partition the current block into lower blocks by using the sequential quad-tree structure.