Sound encoder and sound decoder

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 encoder comprising: an encoding means for encoding a sound signal on a frame-by-frame basis so as to produce a plurality of codes part or all of which are variable length codes; a multiplexing order determination means for analyzing the plurality of codes produced by said encoding means so as to determine an order in which the plurality of codes are to be multiplexed; and a multiplexing means for multiplexing the plurality of codes in the order determined by said multiplexing order determination means, and for outputting a multiplexed result as a sound code.  
   
   
       2 . The sound encoder according to  claim 1 , wherein said multiplexing order determination means classifies the plurality of codes into main codes part or all of which are variable length codes and an auxiliary code, and determines the order in which the main codes are to be multiplexed based on the auxiliary code.  
   
   
       3 . The sound encoder according to  claim 1 , wherein said multiplexing means multiplexes the auxiliary code prior to multiplexing the main codes.  
   
   
       4 . The sound encoder according to  claim 2 , wherein when the main codes are information codes provided for a plurality of portions which constitute each frame, said multiplexing order determination means performs an evaluation on each of the plurality of portions which constitute each frame based on the auxiliary code, makes a comparison among evaluations provided for the plurality of portions, and determines the order in which the main codes are to be multiplexed according to the comparison.  
   
   
       5 . The sound encoder according to  claim 4 , wherein the plurality of portions which constitute each frame correspond to a plurality of frequency regions into which a frequency spectrum obtained by converting the sound signal from time domain to frequency domain is divided, respectively.  
   
   
       6 . The sound encoder according to  claim 4 , wherein the plurality of portions which constitute each frame are a plurality of sections into which the sound signal is divided with respect to time.  
   
   
       7 . The sound encoder according to  claim 4 , wherein said multiplexing order determination means calculates an amplitude or power as an evaluation of each of the plurality of portions.  
   
   
       8 . A sound decoder comprising: a demultiplexing order determination means for accepting a sound code on a frame-by-frame basis, and for determining an order in which the sound code is to be demultiplexed into a plurality of codes part or all of which are variable length codes; a demultiplexing means for demultiplexing the sound code into a plurality of codes one by one in the order determined by said demultiplexing order determination means and for outputting them; and a decoding means for decoding the plurality of codes output from said demultiplexing means so as to reproduce a sound signal.  
   
   
       9 . The sound decoder according to  claim 8 , wherein said demultiplexing order determination means classifies the plurality of codes into main codes part or all of which are variable length codes and an auxiliary code, and determines the order in which the sound code is to be demultiplexed into the main codes based on the auxiliary code.  
   
   
       10 . The sound decoder according to  claim 9 , wherein said demultiplexing means separates the auxiliary code prior to separating the main codes.  
   
   
       11 . The sound decoder according to  claim 9 , wherein when the main codes are information codes provided for a plurality of portions which constitute each frame, said demultiplexing order determination means performs an evaluation on each of the plurality of portions which constitute each frame based on the auxiliary code, makes a comparison among evaluations provided for the plurality of portions, and determines the order in which the sound code is to be demultiplexed into the main codes according to the comparison.  
   
   
       12 . The sound decoder according to  claim 11 , wherein the plurality of portions which constitute each frame correspond to a plurality of frequency regions into which a frequency spectrum obtained by converting the sound signal from time domain to frequency domain is divided, respectively.  
   
   
       13 . The sound decoder according to  claim 11 , wherein the plurality of portions which constitute each frame are a plurality of sections into which the sound signal is divided with respect to time.  
   
   
       14 . The sound decoder according to  claim 11 , wherein said demultiplexing order determination means calculates an amplitude or power as an evaluation of each of the plurality of portions.