Systems and methods for performing motion vector prediction using a derived set of motion vectors
This disclosure relates to video coding and more particularly to techniques for performing motion vector prediction. According to an aspect of an invention, a motion vector and a corresponding reference picture identifier for the motion vector are received; a reference picture corresponding to a second motion vector is determined based on the reference picture corresponding to the received motion vector and a current picture; a scaling value is determined based on the determined reference picture, the reference picture corresponding to the received motion vector, and the current picture; and the second motion vector is generated from the received motion vector by scaling with the scaling value.
1. A method of performing motion vector prediction for video data, the method comprising:
determining a syntax element which has a value indicating bi-prediction is used for a current coding unit;
determining a flag which has a value indicating one of: a first mode of bi-prediction or a second mode of bi-prediction;
for the first mode of bi-prediction, performing inter prediction by:
inferring an index value for a first reference picture list;
generating a first motion vector based on a first signaled index value indicating a first motion vector predictor and a signaled value indicating a first motion vector difference value;
inferring an index value for a second reference picture list; and
generating a second motion vector based on a second signaled index value indicating a second motion vector predictor and a second motion vector difference value, wherein the second motion vector difference value is a scaled version of the first motion vector difference value; and
for the second mode of bi-prediction, performing inter prediction by:
determining an index value for a first reference picture list from a signaled index value; and
determining an index value for a second reference picture list from a signaled index value.
2. A device comprising one or more processors configured to perform steps of claim 1 .
3. The device of claim 2 , wherein the device includes a video encoder.
4. The device of claim 2 , wherein the device includes a video decoder.
5. A non-transitory computer-readable storage medium comprising instructions stored thereon that, when executed, cause one or more processors of a device for decoding video data to perform steps of claim 1 .