Coding affine prediction motion information for video coding

A device for coding video data, the device comprising:

• a memory configured to store video data;
• and
• one or more processors implemented in circuitry and configured to:
• code a first motion vector difference (MVD) representing a difference between a first motion vector of a current block of video data predicted using affine prediction and a first motion vector predictor (MVP) for the first motion vector;
• predict a second MVD from the first MVD for a second motion vector of the current block, the second MVD representing a second difference between the second motion vector and a second MVP for the second motion vector, the second motion vector being different than the first motion vector;
• and
• code the current block using affine prediction according to the first motion vector and the second motion vector.

A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause a processor of a device for coding video data to:

• code a first motion vector difference (MVD) representing a difference between a first motion vector of a current block of video data predicted using affine prediction and a first motion vector predictor (MVP) for the first motion vector;
• predict a second MVD from the first MVD for a second motion vector of the current block, the second MVD representing a second difference between the second motion vector and a second MVP for the second motion vector, the second motion vector being different than the first motion vector;
• and
• code the current block using affine prediction according to the first motion vector and the second motion vector.

A device for coding video data, the device comprising:

• means for coding a first motion vector difference (MVD) representing a difference between a first motion vector of a current block of video data predicted using affine prediction and a first motion vector predictor (MVP) for the first motion vector;
• means for predicting a second MVD from the first MVD for a second motion vector of the current block, the second MVD representing a second difference between the second motion vector and a second MVP for the second motion vector, the second motion vector being different than the first motion vector;
• and
• means for coding the current block using affine prediction according to the first motion vector and the second motion vector.