Single direction long interpolation filter

An apparatus for determining a prediction block, the apparatus comprising:

• a processor configured to execute operations to:
• select a first interpolation filter for a first direction of the prediction block, the first interpolation filter having a first number of taps;
• select a second interpolation filter for a second direction of the prediction block, the second interpolation filter having a second number of taps;
• in response to determining that the second number of taps is greater than a threshold number of taps, set the second interpolation filter to an interpolation filter having a third number of taps, wherein the third number of taps is smaller than or equal to the threshold number of taps;
• and
• generate the prediction block using the first interpolation filter and the second interpolation filter, wherein to generate the prediction block comprises to:
• determine intermediate pixel values for the prediction block using the one of the first interpolation filter and the second interpolation filter having a smaller number of taps;
• and
• determine prediction pixel values for the prediction block using the intermediate pixel values and the other of the first interpolation filter and the second interpolation filter.

An apparatus for generating a prediction block by a decoder, the apparatus comprising:

• a processor configured to execute operations to:
• receive a first interpolation filter having a first number of taps for a first direction of the prediction block and a second interpolation filter having a second number of taps for a second direction of the prediction block;
• in response to determining that the first number of taps does not equal the second number of taps, generate intermediate pixel values for the prediction block using the one of the first interpolation filter and the second interpolation filter having a smaller number of taps;
• in response to determining that the first number of taps equals the second number of taps, generate the intermediate pixel values for the prediction block using either of the first interpolation filter or the second interpolation filter;
• and
• generate prediction pixels using the intermediate pixel values and the other of the first interpolation filter and the second interpolation filter that is not used to generate the intermediate pixel values.