Intra video coding using a decoupled tree structure

A device comprising:

• a memory configured to store video data;
• and
• processing circuitry in communication with the memory, the processing circuitry being configured to:
• determine an intra prediction mode for a chroma block a chroma component of a picture of the video data based on an intra prediction mode of a corresponding luma block of a luma component of the picture, the corresponding luma block being one of a plurality of luma blocks defined using a first partitioning tree structure that is separate from a second partitioning tree structure of the chroma component of the picture that includes the chroma block, wherein the plurality of luma blocks are located at positions of the picture corresponding to a position of the chroma block within the picture, wherein to determine the intra prediction mode for the chroma block, the processing circuitry is configured to:
• determine a width and a height of the chroma block;
• calculate a center position using a formula that uses x and y coordinates indicating a position of the chroma block in the picture and the width and the height of the chroma block as inputs;
• determine the corresponding luma block to be the one of the plurality of luma blocks that is located at a position in the picture corresponding to the calculated center position;
• and
• derive the intra prediction mode for the chroma block as the intra prediction mode for the determined corresponding luma block;
• and
• code the chroma block according to the determined intra prediction mode.

A non-transitory computer-readable medium having stored thereon instructions that when executed by a processor cause the processor to:

• determine an intra prediction mode for a chroma block a chroma component of a picture of the video data based on an intra prediction mode of a corresponding luma block of a luma component of the picture, the corresponding luma block being one of a plurality of luma blocks defined using a first partitioning tree structure that is separate from a second partitioning tree structure of the chroma component of the picture that includes the chroma block, wherein the plurality of luma blocks are located at positions of the picture corresponding to a position of the chroma block within the picture, wherein the instructions cause the processor to:
• determine a width and a height of the chroma block;
• calculate a center position using a formula that uses x and y coordinates indicating a position of the chroma block in the picture and the width and the height of the chroma block as inputs;
• determine the corresponding luma block to be the one of the plurality of luma blocks that is located at a position in the picture corresponding to the calculated center position;
• and
• derive the intra prediction mode for the chroma block as the intra prediction mode for the determined corresponding luma block;
• and
• code the chroma block according to the determined intra prediction mode.