Device and method for coding video data based on one or more reference lines

1. A method of decoding a bitstream by an electronic device, the method comprising:

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

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

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

determining 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;

comparing 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;

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

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

2. The method 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 one of the plurality of reference lines adjacent to the block unit and indicated by the first predefined value.

3. The method 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 method 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 one of the plurality of reference lines.

5. An electronic device for decoding a bitstream, the electronic device comprising:

at least one processor; and

a storage device coupled to the at least one processor and storing a plurality of instructions which, when executed by the at least one processor, causes the at least one processor 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.

6. The electronic device according to claim 5 , 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 one of the plurality of reference lines adjacent to the block unit and indicated by the first predefined value.

7. The electronic device according to claim 6 , wherein the prediction mode is selected from the MPM list including a plurality of most probable modes determined from the plurality of mode candidates when the selected one of the plurality of reference lines is different from the first one of the plurality of reference lines.

8. A method of decoding a bitstream by an electronic device, the method comprising:

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

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

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

directly determining 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;

comparing 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

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

9. The method according to claim 8 , 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.

10. The method according to claim 9 , 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.

11. The method according to claim 9 , 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.