Encoding method based on encoding order change and device therefor, and decoding method based on encoding order change and device therefor

A video decoding device comprising:

• a block splitter configured to obtain, from a bitstream, split information indicating whether a current coding unit is to be split into at least two lower coding units, and split the current coding unit into the at least two lower coding units when the split information indicates that the current coding unit is to be split into the at least two lower coding units;
• an encoding order determiner configured to, when the current coding unit is split into the at least two lower coding units, obtain, from the bitstream, encoding order information indicating a decoding order of the at least two lower coding units, including horizontally neighboring lower coding units, of the current coding unit, and determine whether the decoding order of the at least two lower coding units is a first order from a left lower coding unit to a right lower coding unit, among the horizontally neighboring lower coding units, or a second order from the right lower coding unit to the left lower coding unit, based on the encoding order information;
• a prediction method determiner configured to determine an affine mode on the left lower coding unit;
• and
• a decoder configured to perform inter prediction in the affine mode on the left lower coding unit,
• characterized in that:
• when the right lower coding unit is intra-predicted prior to the left lower coding unit, among the horizontally neighboring lower coding units, according to the second order, the prediction method determiner determines an intra prediction mode of the right lower coding unit, and determines a most probable mode (MPM) list of the left lower coding unit by using the intra prediction mode of the right lower coding unit, and
• the decoder performs intra-prediction on the left lower coding unit by using an intra prediction mode selected from the MPM list.

A video encoding method comprising:

• splitting a current coding unit into at least two lower coding units;
• generating split information indicating whether the current coding unit is to be split into the at least two lower coding units;
• determining an encoding order of horizontally neighboring lower coding units, among the at least two lower coding units, of the current coding unit, and generating encoding order information indicating whether the encoding order of the horizontally neighboring lower coding units is a first order from a left lower coding unit to a right lower coding unit, among the horizontally neighboring lower coding units, or a second order from the right lower coding unit to the left lower coding unit;
• and
• outputting a bitstream comprising the split information and the encoding order information,
• characterized in that the generating of the encoding order information comprises:
• when the right lower coding unit is intra-predicted prior to the left lower coding unit, among the horizontally neighboring lower coding units, according to the second order, determining an intra prediction mode of the right lower coding unit;
• determining a most probable mode (MPM) list of the left lower coding unit by using the intra prediction mode of the right lower coding unit;
• and
• performing intra-prediction on the left lower coding unit by using an intra prediction mode selected from the MPM list.