Coding apparatus for digital signals.

摘要

A coding apparatus comprising a band division filter (11) for dividing an input digital signal into signal components in a plurality of frequency bands, a block floating circuit (16) for implementing, every block, floating processing of an output signal of the band division filter (11), a plurality of orthogonal transform circuits (13, 14, 15) for orthogonally transforming respective output signals on the time base of the block floating circuit to signals on the frequency base, and an adaptive bit allocation encoder (18) for dividing output signals of the orthogonal transform circuits (13, 14, 15) into signal components in critical bands adaptively to allocate bit numbers thereto on the basis of allowed noise levels of respective critical bands, wherein the length in the time base direction of the blocks is caused to be variable, and the length in the time base direction of the blocks and a floating coefficient used in the floating processing are determined on the basis of the same index.