HIGH-QUALITY AUDIO TRANSFORM CODING AT 64-KBPS

This paper presents a transform coding algorithm devoted to high quali ty audio coding at a bit rate of 64 kbps per monophonic channel. It en ables the transmission of a high quality stereo sound through the basi c access (2B channels) of ISDN. Although a complete system including f raming, synchronization and error correction has been developed, only the bit rate compression algorithm is described here. A detailed analy sis of the signal processing techniques such as the time/frequency tra nsformation, the pre-echo reduction by adaptive filtering, the fast al gorithm computations, etc., is provided. The use of psychoacoustical p roperties is also precisely reported. Finally, some subjective evaluat ion results and one real time implementation of the coder using the AT T DSP32C digital signal processor are presented.