Non-transitory computer-readable medium for selecting a prediction mode based on a line index

1. A non-transitory computer-readable medium of a device storing one or more computer-executable instructions for decoding a bitstream, the one or more computer-executable instructions, when executed by one or more processors of the device, cause the device to:

determine a block unit from an image frame according to the bitstream;

determine a line index of the block unit in the bitstream;

compare the line index with a first predefined value to determine whether a mode flag is included in the bitstream;

determine a mode index in the bitstream for directly selecting a prediction mode of the block unit from a most probable mode (MPM) list of the block unit when the mode flag is not included in the bitstream;

compare the mode flag to a second predefined value when the mode flag is included in the bitstream to determine whether the prediction mode is selected from the MPM list based on the mode index;

select one of a plurality of reference lines based on the line index; and

reconstruct the block unit based on the selected one of the plurality of reference lines and the prediction mode.

2. The non-transitory computer-readable medium according to claim 1 , wherein the prediction mode of the block unit is selected from a plurality of mode candidates based on the mode flag when the selected one of the plurality of reference lines is identical to a first reference line in the plurality of reference lines, the first reference line being adjacent to the block unit and indicated by the first predefined value.

3. The non-transitory computer-readable medium according to claim 2 , wherein:

the plurality of mode candidates is categorized into the MPM list and a non-MPM list; and

the mode flag indicates in which one of the MPM list and the non-MPM list the prediction mode is included.

4. The non-transitory computer-readable medium according to claim 2 , wherein the prediction mode is selected based on the mode index from the MPM list without parsing the mode flag when the selected one of the plurality of reference lines is different from the first reference line.

5. A non-transitory computer-readable medium of a device storing one or more computer-executable instructions for decoding a bitstream, the one or more computer-executable instructions, when executed by one or more processors of the device, cause the device to:

determine a block unit from an image frame according to the bitstream;

determine a line index in the bitstream for selecting a prediction line of the block unit from a plurality of reference lines;

determine, based on the line index, whether a mode flag is included in the bitstream;

directly determine a most probable mode (MPM) index from the bitstream for selecting a prediction mode of the block unit from an MPM list of the block unit when the mode flag is not included in the bitstream;

compare the mode flag with a predefined value for selecting one of the MPM index and a non-MPM index to determine the prediction mode when the mode flag is included in the bitstream; and

reconstruct the block unit based on the prediction line and the prediction mode.

6. The non-transitory computer-readable medium according to claim 5 , wherein:

the mode flag is included in the bitstream for indicating the selected one of the MPM index and the non-MPM index when the prediction line indicated by the line index is identical to a first one of the plurality of reference lines, and

the first one of the plurality of reference lines is adjacent to the block unit.

7. The non-transitory computer-readable medium according to claim 6 , wherein the prediction mode is selected directly based on the MPM index from the MPM list without parsing the mode flag when the prediction line is different from the first one of the plurality of reference lines.

8. The non-transitory computer-readable medium according to claim 6 , wherein the mode flag is not included in the bitstream when the prediction line is different from the first one of the plurality of reference lines.