Video image coding and decoding method and apparatus

A video image coding method, comprising:

• coding a coding tree node in a video image based on at least one split mode in a specified candidate split mode set of the coding tree node, to obtain a rate-distortion cost corresponding to each of the at least one split mode, wherein the rate-distortion cost is a sum of rate-distortion costs of all coding units obtained based on corresponding split modes, an aspect ratio of the coding tree node is 1 and a width of the coding tree node is greater than a preset threshold, the candidate split mode set comprises a first split mode for indicating that the coding tree node is a basic coding unit of the video image, a second split mode for determining that the coding tree node comprises two equal-sized lower-level nodes with an aspect ratio of 2, a third split mode for determining that the coding tree node comprises two equal-sized lower-level nodes with an aspect ratio of 0.5, and a fourth split mode for determining that the coding tree node comprises four equal-sized lower-level nodes with an aspect ratio of 1, and when an aspect ratio of the lower-level node is 1 and a width of the lower-level node is greater than the preset threshold, a candidate split mode set of the lower-level node is the same as the candidate split mode set of the coding tree node;
• determining a split mode with a minimum rate-distortion cost as a target split mode of the coding tree node;
• and
• determining, based on the target split mode, each coding unit comprised in the coding tree node, and coding each coding unit to obtain a bitstream and a reconstruction image that are corresponding to the coding tree node.

A video image decoding apparatus, wherein a coding tree node is used to indicate a to-be-decoded rectangular image area in a video image, a lower-level node is used to indicate a part of the to-be-decoded rectangular image area, image areas indicated by different lower-level nodes do not overlap each other, and when the coding tree node is a coding unit of the video image, the coding tree node does not comprise the lower-level node, the apparatus comprising:

• a non-transitory memory having processor-executable instructions stored thereon;
• and
• a processor, coupled to the memory, configured to execute the processor-executable instructions to facilitate:
• parse split mode information of the coding tree node in a bitstream;
• obtain a split mode of the coding tree node from a candidate split mode set of the coding tree node based on the split mode information, wherein an aspect ratio of the coding tree node is 1 and a width of the coding tree node is greater than a preset threshold, the candidate split mode set comprises a first split mode for indicating that the coding tree node is the coding unit of the video image, a second split mode for determining that the coding tree node comprises two equal-sized lower-level nodes with an aspect ratio of 2, a third split mode for determining that the coding tree node comprises two equal-sized lower-level nodes with an aspect ratio of 0.5, and a fourth split mode for determining that the coding tree node comprises four equal-sized lower-level nodes with an aspect ratio of 1, and when an aspect ratio of the lower-level node is 1 and a width of the lower-level node is greater than the preset threshold, a candidate split mode set of the lower-level node is the same as the candidate split mode set of the coding tree node;
• and parse the bitstream to obtain coding information of the coding tree node;
• and
• reconstruct a pixel value of the coding tree node based on the split mode information and the coding information of the coding tree node.