Systems and methods for performing intra prediction coding in video coding

1. A method of decoding video data, the method comprising:

parsing a first syntax element specifying an intra prediction reference line index, wherein the first syntax element is an intra luma reference index syntax element having a value of one of 0, 1, and 2, wherein each of the values of 0, 1, and 2 specifies a distinct reference line index to generate reference samples;

parsing a second syntax element, only in a case that a value of the first syntax element is equal to 0, wherein the second syntax element specifies whether a current intra coding unit is partitioned into transform block sub partitions, and the second syntax element is an intra sub partitions mode flag;

parsing a third syntax element indicating a fourth syntax element is parsed or a fifth syntax element is parsed;

parsing one of the fourth syntax element and the fifth syntax element based on a value of the third syntax element;

deriving a variable specifying the intra prediction reference line index by using the first syntax element; and

generating predicted samples for a current transform block based on one of the fourth syntax element and the fifth syntax element, wherein

in a case that an intra prediction mode indicates an INTRA_DC intra prediction mode,

the predicted samples are derived based on a neighboring left sample defined by the variable and a neighboring above sample defined by the variable, in a case that a transform block width is equal to a transform block height;

the predicted samples are derived based on only neighboring above samples defined by the variable, in a case that the transform block width is greater than the transform block height; and

the predicted samples are derived based on only neighboring left samples defined by the variable, in a case that the transform block width is less than the transform block height.

2. A device for decoding video data, the device comprising one or more processors configured to:

parse a first syntax element specifying an intra prediction reference line index, wherein the first syntax element is an intra luma reference index syntax element having a value of one of 0, 1, and 2, wherein each of the values of 0, 1, and 2 specifies a distinct reference line index to generate reference samples;

parse a second syntax element, only in a case that a value of the first syntax element is equal to 0, wherein the second syntax element specifies whether a current intra coding unit is partitioned into transform block sub partitions, and the second syntax element is an intra sub partitions mode flag;

parse a third syntax element indicating a fourth syntax element is parsed or a fifth syntax element is parsed;

parse one of the fourth syntax element and the fifth syntax element based on a value of the third syntax element;

derive a variable specifying the intra prediction reference line index by using the first syntax element; and

generate predicted samples for a current transform block based on one of the fourth syntax element and the fifth syntax element, wherein

in a case that an intra prediction mode indicates an INTRA_DC intra prediction mode,

the predicted samples are derived based on a neighboring left sample defined by the variable and a neighboring above sample defined by the variable, in a case that a transform block width is equal to a transform block height;

the predicted samples are derived based on only neighboring above samples defined by the variable, in a case that the transform block width is greater than the transform block height; and

the predicted samples are derived based on only neighboring left samples defined by the variable, in a case that the transform block width is less than the transform block height.

3. The device of claim 2 , wherein the device includes a video decoder.

4. A device for encoding video data, the device comprising one or more processors configured to:

parse a first syntax element specifying an intra prediction reference line index, wherein the first syntax element is an intra luma reference index syntax element having a value of one of 0, 1, and 2, wherein each of the values of 0, 1, and 2 specifies a distinct reference line index to generate reference samples;

parse a second syntax element, only in a case that a value of the first syntax element is equal to 0, wherein the second syntax element specifies whether a current intra coding unit is partitioned into transform block sub partitions, and the second syntax element is an intra sub partitions mode flag;

parse a third syntax element indicating a fourth syntax element is parsed or a fifth syntax element is parsed;

parse one of the fourth syntax element and the fifth syntax element based on a value of the third syntax element;

derive a variable specifying the intra prediction reference line index by using the first syntax element; and

generate predicted samples for a current transform block based on one of the fourth syntax element and the fifth syntax element, wherein

in a case that an intra prediction mode indicates an INTRA_DC intra prediction mode,

the predicted samples are derived based on a neighboring left sample defined by the variable and a neighboring above sample defined by the variable, in a case that a transform block width is equal to a transform block height;

the predicted samples are derived based on only neighboring above samples defined by the variable, in a case that the transform block width is greater than the transform block height; and

the predicted samples are derived based on only neighboring left samples defined by the variable, in a case that the transform block width is less than the transform block height.

5. The device of claim 2 , wherein the third syntax element is an intra luma most probable mode flag.

6. The device of claim 2 , wherein the fourth syntax element is an intra luma most probable mode index.

7. The device of claim 2 , wherein the fifth syntax element is an intra luma most probable mode remainder.