Signaling for zero residual flag and prediction mode

A device for decoding a video bitstream, the device comprising a memory for storing computer instructions and a processor in communication with the memory, wherein, when the processor executes the computer instructions, the processor is configured to cause the device to:

• receive the video bitstream comprising a current picture, the current picture comprising a current block, and the current block comprising a current transform block;
• determine a skip transform flag indicating whether the current transform block has all zero coefficient or not via one of:
• receiving the skip transform flag from the video bitstream;
• or
• deriving the skip transform flag;
• derive, based on the skip transform flag, at least one of following flags:
• an intra block copy flag indicating whether Intra Block Copy is applied to the current block;
• or
• an inter prediction flag indicating whether the current block is coded in inter-prediction mode;
• and
• reconstruct the current block based on at least one of:
• the intra block copy flag, the inter prediction flag.

A non-transitory storage medium for storing computer readable instructions, the computer readable instructions, when executed by a processor in a decoder for decoding a video bitstream, causing the processor to:

• receive the video bitstream comprising a current picture, the current picture comprising a current block, and the current block comprising a current transform block;
• determine a skip transform flag indicating whether the current transform block has all zero coefficient or not via one of:
• receiving the skip transform flag from the video bitstream;
• or
• deriving the skip transform flag;
• derive, based on the skip transform flag, at least one of following flags:
• an intra block copy flag indicating whether Intra Block Copy is applied to the current block;
• or
• an inter prediction flag indicating whether the current block is coded in inter-prediction mode;
• and
• reconstruct the current block based on at least one of:
• the intra block copy flag, the inter prediction flag.