Hardware friendly design for intra mode coding

A method of intra prediction mode coding in video encoding, the method comprising:

• receiving, by a device comprising a memory storing instructions and a processor in communication with the memory, video data;
• constructing, by the device, a list of intra modes for a block in the video data according to a pre-defined rule based on a size of the block;
• dividing, by the device, the list of intra modes into a plurality of intra mode sets for the block;
• determining, by the device, a set index indicating an intra mode set from the plurality of intra mode sets;
• encoding, by the device, the set index into a coded video bitstream;
• determining, by the device, a mode index indicating an intra prediction mode from the intra mode set;
• encoding, by the device, the mode index into the coded video bitstream;
• determining, by the device, the intra prediction mode for the block based on the set index and the mode index;
• and
• encoding, by the device, the block into the coded video bitstream based on the intra prediction mode,
• wherein:
• when the size of the block is equal to or greater than a first threshold:
• the list of intra modes comprises a first sub-list being at a top of the list, and
• the first sub-list comprises all non-directional intra prediction modes.

A method of processing video data, the method comprising:

• performing, by a device comprising a memory storing instructions and a processor in communication with the memory, a conversion between video data and a bitstream by:
• constructing, by the device, a list of intra modes for a block in the video data according to a pre-defined rule based on a size of the block;
• dividing, by the device, the list of intra modes into a plurality of intra mode sets for the block;
• determining, by the device, a set index indicating an intra mode set from the plurality of intra mode sets;
• encoding, by the device, the set index into the bitstream;
• determining, by the device, a mode index indicating an intra prediction mode from the intra mode set;
• encoding, by the device, the mode index into the bitstream;
• determining, by the device, the intra prediction mode for the block based on the set index and the mode index;
• and
• encoding, by the device, the block into the bitstream based on the intra prediction mode,
• wherein:
• when the size of the block is equal to or greater than a first threshold:
• the list of intra modes comprises a first sub-list being at a top of the list, and
• the first sub-list comprises all non-directional intra prediction modes.