Video encoding method and apparatus, and video decoding method and apparatus using blocks split in various shapes from images

1. A video decoding method comprising:

determining a largest size of a coding unit, by using information about the largest size of the coding unit, the information being obtained from a bitstream;

obtaining, from the bitstream, information about a largest size of a block allowed to be ternary split, information about a smallest size of the block allowed to be ternary split, and information about a largest size of a coding unit with a height width ratio of 1:4;

determining the largest size of the block allowed to be ternary split, by using the largest size of the coding unit and the information about the largest size of the block allowed to be ternary split;

determining the smallest size of the block allowed to be ternary split, by using a smallest size of the coding unit and the information about the smallest size of the block allowed to be ternary split;

determining the largest size of the coding unit with the height width ratio of 1:4 by using the information about the largest size of the coding unit with the height width ratio of 1:4;

determining the smallest size of the coding unit with the height width ratio of 1:4 from the smallest size of the coding unit;

determining whether to allow ternary split of a first coding unit, based on the largest size of the block allowed to be ternary split, the smallest size of the block allowed to be ternary split, the largest size of the coding unit with the height width ratio of 1:4 and the smallest size of the coding unit with the height width ratio of 1:4;

when the ternary split of the first coding unit is allowed, generating second coding units with the height width ratio of 1:4 by ternary splitting the first coding unit and decoding the second coding units; and

when the first coding unit is not split into smaller coding units, decoding the first coding unit.

2. A video encoding method comprising:

determining a largest size of a coding unit, a smallest size of the coding unit, a largest size of a block allowed to be ternary split, a smallest size of the block allowed to be ternary split, a largest size of a coding unit with a height width ratio of 1:4, and a smallest size of the coding unit with the height width ratio of 1:4;

determining whether to allow ternary split of a first coding unit, based on the largest size of the block allowed to be ternary split, the smallest size of the block allowed to be ternary split, the largest size of the coding unit with the height width ratio of 1:4 and the smallest size of the coding unit with the height width ratio of 1:4;

when the ternary split of the first coding unit is allowed, generating second coding units with the height width ratio of 1:4 by ternary splitting the first coding unit and encoding the second coding units;

when the first coding unit is not split into smaller coding units, encoding the first coding unit;

encoding information about the largest size of the coding unit, based on the largest size of the coding unit;

encoding information about the largest size of the block allowed to be ternary split, by using the largest size of the coding unit and the largest size of the block allowed to be ternary split;

encoding information about the smallest size of the block allowed to be ternary split, by using the smallest size of the coding unit and the smallest size of the block allowed to be ternary split; and

encoding information about the largest size of the coding unit with the height width ratio of 1:4 by using the largest size of the coding unit with the height width ratio of 1:4.

3. A method of storing a bitstream into a non-transitory computer-readable storage medium, the method comprising:

determining a largest size of a coding unit, a smallest size of the coding unit, a largest size of a block allowed to be ternary split, a smallest size of the block allowed to be ternary split, a largest size of a coding unit with a height width ratio of 1:4, and a smallest size of the coding unit with the height width ratio of 1:4;

determining whether to allow ternary split of a first coding unit, based on the largest size of the block allowed to be ternary split, the smallest size of the block allowed to be ternary split, the largest size of the coding unit with the height width ratio of 1:4 and the smallest size of the coding unit with the height width ratio of 1:4;

when the ternary split of the first coding unit is allowed, generating second coding units with the height width ratio of 1:4 by ternary splitting the first coding unit and encoding the second coding units;

when the first coding unit is not split into smaller coding units, encoding the first coding unit;

encoding information about the largest size of the coding unit, based on the largest size of the coding unit;

encoding information about the largest size of the block allowed to be ternary split, by using the largest size of the coding unit and the largest size of the block allowed to be ternary split; and

encoding information about the smallest size of the block allowed to be ternary split, by using the smallest size of the coding unit and the smallest size of the block allowed to be ternary split;

encoding information about the largest size of the coding unit with the height width ratio of 1:4 by using the largest size of the coding unit with the height width ratio of 1:4; and

storing, into the non-transitory computer-readable storage medium, the bitstream including the information about the largest size of the block allowed to be ternary split, the information about the smallest size of the block allowed to be ternary split and the information about the largest size of the coding unit with the height width ratio of 1:4.