Artificial intelligence based video decoding apparatus and video decoding method and artificial intelligence based video encoding apparatus and video encoding method which perform chroma component prediction

An artificial intelligence (AI)-based video decoding apparatus comprising:

• a memory storing at least one instruction;
• and
• at least one processor configured to operate according to the at least one instruction, wherein the at least one processor is further configured to:
• obtain, from a bitstream, a joint chroma residual sample of a current block, Cb component prediction information of the current block, and Cr component prediction information of the current block, the current block comprising a Cb component and a Cr component,
• determine a prediction sample of the Cb component of the current block based on at least the Cb component prediction information,
• determine a prediction sample of the Cr component of the current block based on at least the Cr component prediction information, and
• reconstruct the current block by obtaining a reconstructed sample of the Cb component of the current block and a reconstructed sample of the Cr component of the current block as an output of a neural network for reconstructing the Cb component and the Cr component by inputting data obtained by concatenating the joint chroma residual sample, the prediction sample of the Cb component, and the prediction sample of the Cr component for each sample of the current block to the neural network,
• wherein the joint chroma residual sample represents residual information jointly corresponding to the Cb component and the Cr component of the current block,
• wherein the neural network is trained to determine a correlation between the Cb component and the Cr component for each sample of the current block by receiving the joint chroma residual sample, the prediction sample of the Cb component, and the prediction sample of the Cr component as inputs,
• wherein a plurality of models for the neural network are determined based on whether a prediction type of the current block is an intra prediction or an inter prediction, and
• wherein a model of the neural network is determined from among the plurality of models.

An artificial intelligence (AI)-based video encoding method comprising:

• generating an initial joint chroma residual sample of a current block, Cb component prediction information of the current block, and Cr component prediction information of the current block;
• determining a prediction sample of a Cb component of the current block based on at least the Cb component prediction information,
• determining a prediction sample of a Cr component of the current block based on at least the Cr component prediction information;
• and
• encoding a joint chroma residual sample of the current block by obtaining a reconstructed sample of the Cb component of the current block and a reconstructed sample of the Cr component of the current block as an output of a neural network for reconstructing the Cb component and the Cr component by inputting data obtained by concatenating the initial joint chroma residual sample, the prediction sample of the Cb component, and the prediction sample of the Cr component for each sample of the current block to the neural network,
• wherein the joint chroma residual sample represents residual information jointly corresponding to the Cb component and the Cr component of the current block,
• wherein the neural network is trained to determine a correlation between the Cb component and the Cr component for each sample of the current block by receiving the joint chroma residual sample, the prediction sample of the Cb component, and the prediction sample of the Cr component as inputs,
• wherein a plurality of models for the neural network are determined based on whether a prediction type of the current block is an intra prediction or an inter prediction, and
• wherein a model of the neural network is determined from among the plurality of models.