AUDIO ENCODING APPARATUS, AUDIO DECODING APPARATUS, COMMUNICATION APPARATUS AND AUDIO ENCODING METHOD

摘要

An audio encoding apparatus and the like are disclosed which can improve the sound quality of encoded audio signals even in a case of scalable CELP encoding the audio signals in sections that vary with time. In this apparatus, an enhancement layer extended adaptive codebook generating part (102) generates an extended adaptive codebook (d_enh_ext[i]) from both one frame of core layer drive sound source signals (exc_core[n]) received from a core layer CELP encoding part (101) and past enhancement layer drive sound source signals (exc_enh[n]) received from an adder (106), and further inputs the generated extended adaptive codebook (d_enh_ext[i]) to an enhancement layer extended adaptive codebook (103) for each of sub-frames. That is, the enhancement layer extended adaptive codebook generating part (102) updates the extended adaptive codebook (d_enh_ext[i]) for each of the sub-frames.