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

摘要

An audio encoding method, an audio decoding method, an audio encoding apparatus and an audio decoding apparatus wherein a low delay and a high quality can be achieved and the degradation of sound quality caused by a transmission error is reduced. At the end of an encoding apparatus, audio signals are divided into a plurality of frequency bands; down-sampled signals are adaptive-difference-encoded for each of the bands; they are classified into significant bits and non-significant bits in accordance with the degree of degradation of decoded audio during occurrence of a transmission error; and a CRC code is added only to a significant bit sequence. At a decoding apparatus (300), when a CRC error detector (202) detects an error, a code word limiter (204) limits a code word; a pitch extractor (302) successively calculates a basic frequency; a duplicate addition to a previous pitch waveform is performed; and a band combining filter bank (209) decodes the audio signal.