Systems and methods for signaling reference picture lists in video coding

A device of decoding video data, the device comprising:

• a processor configured to:
• parse a weighted prediction flag and a weighted bi-prediction flag in a sequence parameter set;
• receive a reference picture list structure;
• parse a first syntax element specifying a number of entries in the reference picture list structure;
• parse a second syntax element specifying a value of a first variable, wherein the second syntax element is defined by an index for a range of 0 to a value of the first syntax element minus one;
• set the value of the first variable, wherein
• in a case that (i) a first condition, which is a value of the weighted prediction flag or a value of the weighted bi-prediction flag is equal to one, is true and (ii) a value of the index is not equal to zero, the value of the first variable is set equal to a value of the second syntax element, and
• in every case that the value of the index is equal to zero, the value of the first variable is set equal to the value of the second syntax element plus one;
• parse a third syntax element, in a case that the value of the first variable is greater than zero, wherein the third syntax element specifies whether a second variable is greater than or equal to 0;
• and
• derive a value for the second variable based on the value of the first variable and a value of the third syntax element.

A method of encoding image data, the method comprising:

• signaling a sequence parameter set including a weighted prediction flag and a weighted bi-prediction flag;
• signaling a reference picture list structure,
• wherein:
• the reference picture list structure includes:
• (i) a first syntax element specifying a number of entries in the reference picture list structure,
• (ii) a second syntax element specifying a value of a first variable, wherein the second syntax element is defined by an index for a range of 0 to a value of the first syntax element minus one,
• in a case that (i) a first condition, which is a value of the weighted prediction flag or a value of the weighted bi-prediction flag is equal to one, is true and (ii) a value of the index is not equal to zero, the value of the first variable is set equal to a value of the second syntax element, and
• in every case that the value of the index is equal to zero, the value of the first variable is set equal to a value of the second syntax element plus one, and
• (iii) a third syntax element, in a case that the value of the first variable is greater than zero, wherein the third syntax element specifies whether a second variable is greater than or equal to 0, and a value for the second variable is derived based on the value of the first variable and a value of the third syntax element.

A device of encoding image data, the device comprising:

• a processor configured to:
• signal a sequence parameter set including a weighted prediction flag and a weighted bi-prediction flag;
• and
• signal a reference picture list structure,
• wherein:
• the reference picture list structure includes:
• (i) a first syntax element specifying a number of entries in the reference picture list structure,
• (ii) a second syntax element specifying a value of a first variable, wherein the second syntax element is defined by an index for a range of 0 to a value of the first syntax element minus one,
• in a case that (i) a first condition, which is a value of the weighted prediction flag or a value of the weighted bi-prediction flag is equal to one, is true and (ii) a value of the index is not equal to zero, the value of the first variable is set equal to a value of the second syntax element, and
• in every case that the value of the index is equal to zero, the value of the first variable is set equal to a value of the second syntax element plus one, and
• (iii) a third syntax element, in a case that the value of the first variable is greater than zero, wherein the third syntax element specifies whether a second variable is greater than or equal to 0, and a value for the second variable is derived based on the value of the first variable and a value of the third syntax element.