CPC H04N 19/159 (2014.11) [H04N 19/12 (2014.11); H04N 19/176 (2014.11); H04N 19/61 (2014.11); H04N 19/625 (2014.11)] | 3 Claims |
1. An encoder comprising:
memory; and
a processor coupled to the memory, the processor being configured to:
when intra prediction is used for a current block, (a) determine whether a basis selection mode in which a first transform basis is selectable from among a plurality of first transform basis candidates is used and (b) determine whether a size of the current block satisfies a predetermined condition;
when the basis selection mode is used for the current block and the size of the current block satisfies the predetermined conditions,
(i) perform a first transform with the first transform basis on residual signals of the current block to generate first transform coefficients,
(ii-1) when an intra prediction mode is a predetermined intra prediction mode, quantize the first transform coefficients, and
(ii-2) when the intra prediction mode is not the predetermined intra prediction mode, (a) perform a second transform on the first transform coefficients with a second transform basis to generate second transform coefficients and (b) quantize the second transform coefficients; and
when inter prediction is used for the current block, (a) perform a third transform with a third transform basis selected from among the plurality of first transform basis candidates on the residual signals of the current block to generate third transform coefficients and (b) quantize the third transform coefficient.
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