Patent ID: 7478309

Claim:
An audio decoding method for a signal having been encoded under use of a channel coding per transmission frame ( 314 ) having a plurality of compressed audio frame data ( 310 , 311 , 312 , 313 ), including: a) bits of said plurality of compressed audio frame data ( 310 , 311 , 312 , 313 ) grouped into a plurality of classes ( 320 , 321 , 322 ) according to the degree degradation in decoding quality in the presence of transmission errors; b) each of the plurality of classes ( 320 , 321 , 322 ) having been subjected to different channel coding processes under use of different error protection codes, the audio decoding method comprising the steps of: a receiver receiving the plurality of compressed audio frame data; performing different decoding for transmission frames in each of the plurality of classes ( 320 , 321 , 322 ) grouped in descending order of error protection; ungrouping the plurality of compressed audio frame data ( 310 , 311 , 312 , 313 ) from the plurality of classes ( 320 , 321 , 322 ); and in each of the plurality of compressed audio frame data that is compressed by way of a sub-band ADPCM mode, halting the process of updating a scale factor during ADPCM decoding per sub-band in the presence of an unrecoverable transmission error in said compressed audio frame data.