Sound decoder and sound decoding method with demultiplexing order determination

Abstract

A sound encoder multiplexes a plurality of codes into a sound code in an order determined by a multiplexing order determination unit ( 12 ), and a sound decoder demultiplexes the sound code into a plurality of codes one by one in an order determined by a demultiplexing order determination unit ( 14 ).

1 . A sound decoder comprising:
 a first demultiplexing unit for receiving a sound code on a frame-by-frame basis and for demultiplexing the sound code into an auxiliary code which is multiplexed for each frame in the same fixed order;   a demultiplexing order determination unit for determining an order in which the sound code is to be demultiplexed into main codes, part or all of which are variable length codes, based on an order of the values of the amplitude envelope's elements obtained by an amplitude envelope as an intermediate variable which is produced by the auxiliary code;   a second demultiplexing unit for demultiplexing the sound code into the main codes in the order determined by said demultiplexing order determination unit and for outputting the main codes; and   a decoding unit for decoding the main codes output from said demultiplexing unit so as to reproduce a sound signal.   
   
   
       2 . A sound decoding method comprising:
 a first demultiplexing step for receiving a sound code on a frame-by-frame basis, and for demultiplexing the sound code into an auxiliary code which is multiplexed for each frame in the same fixed order;   a demultiplexing order determination step for determining an order in which the sound code is to be demultiplexed into main codes, part or all of which are variable length codes, based on an order of the values of the amplitude envelope's elements obtained by an amplitude envelope as an intermediate variable which is produced by the auxiliary code;   a second demultiplexing step for demultiplexing the sound code into the main codes in the order determined by said demultiplexing order determination step and for outputting the main codes; and   a decoding step for decoding the main codes output from said demultiplexing step so as to reproduce a sound signal.