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

determining a number of a plurality of reference lines based on the block size;

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;

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

selecting one of the 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 indicated by the first predefined value and adjacent to the block unit.

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 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. The method according to claim 1 , wherein the number of the plurality of reference lines is determined based on a size comparison generated based on the block size and a size threshold.

6. The method according to claim 5 , further comprising:

determining the number of the plurality of reference lines as a predefined quantity, when the size comparison satisfies a predefined condition.

7. The method according to claim 6 , wherein the predefined condition includes at least one of a first condition that the block size is less than a first threshold, a second condition that the block size is greater than a second threshold different from the first threshold, a third condition that a size ratio determined based on a block width and a block height of the block size is less than a third threshold, and a fourth condition that the size ratio is equal to a fourth threshold different from the third threshold.

8. 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 size of a block unit from an image frame according to the bitstream;

determine a number of a plurality of reference lines based on the block size;

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;

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

select one of the 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.

9. The electronic device according to claim 8 , 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 indicated by the first predefined value and adjacent to the block unit.

10. The electronic device according to claim 9 , 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 plurality of reference lines is different from the first one of the plurality of reference lines.

11. The electronic device according to claim 8 , wherein the plurality of instructions, when executed by the at least one processor, further causes the at least one processor to:

determine the number of the plurality of reference lines as a predefined quantity, when a size comparison determined based on the block size and a size threshold satisfies a predefined condition.

12. The electronic device according to claim 11 , wherein the predefined condition includes at least one of a first condition that the block size is less than a first threshold, a second condition that the block size is greater than a second threshold different from the first threshold, a third condition that a size ratio determined based on a block width and a block height of the block size is less than a third threshold, and a fourth condition that the size ratio is equal to a fourth threshold different from the third threshold.

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

determining a block width and a block height of a block unit from an image frame according to the bitstream;

determining a number of a plurality of reference lines based on the block width and the block height;

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;

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

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

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

14. The method according to claim 13 , wherein the prediction mode of the block unit is selected based on the mode index from one of the MPM list and a non-MPM list selected based a mode flag, when the prediction line is identical to a first one of the plurality of reference lines indicated by the first predefined value and adjacent to the block unit.

15. The method according to claim 14 , wherein the prediction mode is selected based on the mode index directly 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.

16. The method according to claim 13 , wherein the number of the plurality of reference lines is determined based on a size comparison determined based on the block width and the block height and a size threshold.

17. The method according to claim 16 , further comprising:

determining the number of the plurality of reference lines as a predefined quantity, when the size comparison satisfies a predefined condition.

18. The method according to claim 17 , wherein the predefined condition includes at least one of a first condition that a block area determined based on the block width and the block height is less than a first threshold, a second condition that the block area is greater than a second threshold different from the first threshold, a third condition that a size ratio determined based on a block width and a block height of the block size is less than a third threshold, and a fourth condition that the size ratio is equal to a fourth threshold different from the third threshold.