MPEG-4 Book, The

11.4. MPEG-4 Scalable Audio Coding

According to the traditional approach to perceptual audio coding (see Section 11.1), the bit rate used for the compressed representation of the audio signal is specified at the time of encoding. This may, however, not be appropriate if the bitstream is to be distributed subsequently via transmission channels not known beforehand or channels with varying transmission capacity (e.g., Internet, wireless transmission). This problem is addressed by the concept of MPEG-4 scalable audio coding, which enables the transmission and decoding of the bitstream with a bit rate that can be adapted to dynamically varying requirements, like the instantaneous transmission channel capacity (or, in some cases, the decoder computational ...