Intra-prediction mode for screen content coding of video coding

A device for decoding video data, the device comprising:

• a memory configured to store video data;
• and
• one or more processors implemented in circuitry and configured to:
• decode a first value for a first syntax element of a current block of the video data, the first value indicating that the current block is encoded using an intra-prediction mode;
• after decoding the first value, decode a second value for a second syntax element of the current block, the second value indicating that the current block is encoded using intra mapping mode;
• generate a prediction block for the current block using the intra-prediction mode;
• in response to decoding the second value, decode a residual block for the current block, wherein to decode the residual block, the one or more processors are configured to, for each quantized residual value for the current block:
• determine a predictor for a current quantized residual value from a neighboring quantized residual value to the current quantized residual value, the predictor being separate from the prediction block;
• entropy decode a mapping value for the current quantized residual value;
• when the mapping value is equal to one, set the current quantized residual value equal to the predictor;
• and
• when the mapping value is not equal to one, set the current quantized residual value equal to the mapping value or the mapping value minus one;
• and
• combine the prediction block with the residual block to decode the current block.

A computer-readable storage medium having stored thereon instructions that, when executed, cause a processor to:

• decode a first value for a first syntax element of a current block of video data, the first value indicating that the current block is encoded using an intra-prediction mode;
• after decoding the first value, decode a second value for a second syntax element of the current block, the second value indicating that the current block is encoded using intra mapping mode;
• generate a prediction block for the current block using the intra-prediction mode;
• in response to decoding the second value, decode a residual block for the current block, comprising instructions that cause the processor to, for each quantized residual value for the current block:
• determine a predictor for a current quantized residual value from a neighboring quantized residual value to the current quantized residual value, the predictor being separate from the prediction block;
• entropy decode a mapping value for the current quantized residual value;
• when the mapping value is equal to one, set the current quantized residual value equal to the predictor;
• and
• when the mapping value is not equal to one, set the current quantized residual value equal to the mapping value or the mapping value minus one;
• and
• combine the prediction block with the residual block to decode the current block.

A device for decoding video data, the device comprising:

• means for decoding a first value for a first syntax element of a current block of video data, the first value indicating that the current block is encoded using an intra-prediction mode;
• means for decoding a second value for a second syntax element of the current block after decoding the first value, the second value indicating that the current block is encoded using intra mapping mode;
• means for generating a prediction block for the current block using the intra-prediction mode;
• means for decoding a residual block for the current block in response to decoding the second value, comprising:
• means for determining a predictor for a current quantized residual value from a neighboring quantized residual value to the current quantized residual value, the predictor being separate from the prediction block;
• means for entropy decoding a mapping value for the current quantized residual value;
• means for setting the current quantized residual value equal to the predictor when the mapping value is equal to one;
• and
• means for setting the current quantized residual value equal to the mapping value or the mapping value minus one when the mapping value is not equal to one;
• and
• means for combining the prediction block with the residual block to decode the current block.