Coding interpolation filter type

A method comprising:

• decoding, by a processor in response to instructions stored on a non-transitory computer readable medium, a current block of a current frame from an encoded video stream, wherein decoding the current block includes:
• identifying previously decoded blocks spatially proximal to the current block in the current frame;
• identifying a motion vector from a selected previously decoded block from the previously decoded blocks spatially proximal to the current block as a selected motion vector for predicting the current block;
• identifying an interpolation filter in response to identifying the motion vector as a selected interpolation filter for predicting the current block;
• and
• reconstructing the current block using the selected motion vector and the selected interpolation filter;
• and
• outputting or storing the current block.

A method comprising:

• generating a first encoded block by encoding a first block from a current frame from an input video stream, wherein encoding the first block includes:
• identifying a first motion vector for predicting the first block;
• and
• identifying a first interpolation filter for predicting the first block;
• outputting the first encoded block by:
• including the first motion vector in an output bitstream;
• and
• including an identifier of the first interpolation filter in the output bitstream;
• generating, by a processor in response to instructions stored on a non-transitory computer readable medium, a second encoded block by encoding a second block from the current frame, wherein encoding the second block includes:
• identifying candidate motion vectors for predicting the second block, wherein the candidate motion vectors include:
• the first motion vector;
• and
• a second motion vector for predicting the second block, wherein the second motion vector differs from the first motion vector, and wherein the second motion vector is a non-zero motion vector;
• identifying, from the candidate motion vectors, a selected motion vector for predicting the second block;
• on a condition that the selected motion vector is the first motion vector:
• identifying the first interpolation filter as a selected interpolation filter for predicting the second block;
• and
• omitting the selected motion vector for predicting the second block and an identifier of the selected interpolation filter for predicting the second block from the output bitstream;
• and
• transmitting or storing the output bitstream.