AUDIO SIGNAL CODING AND DECODING METHODS AND AUDIO SIGNAL CODER AND DECODER

摘要

In order to code an audio signal by using a vector quantization method and thereby reduce the quantity of data, the coding is done by a coding unit (1). When this operation is carried out, an audio code having a minimum distance among the auditive distances between sub-vectors produced by dividing an input vector and audio codes in a transmission-side code book 29003 is selected. A portion corresponding to an element of a sub-vector having a high auditive importance is handled in an audio code selecting unit 2900102 while neglecting the positive and negative codes indicating their phase information, and subjected to comparative retrieval with respect to audio codes in a transmission-side code book 29003, and phase information corresponding to an element portion of the sub-vector extracted separately in a phase information extraction unit 2900107 is added to the result obtained, and the result is output as a code index. Thereby, the calculation amount in the code retrieval of vector quantization and the number of codes in the code book are decreased without lowering the quality of an audio signal auditively during decoding operation. <IMAGE>