Embedded ADPCM for variable bit rate coding in ATM

This paper introduces a variable bit rate coding algorithm combining silence detection and embedded ADPCM. The bit rate controlling method are discussed in the paper. The result shows that the bit rate of this coding algorithm method can be effectively reduced to below 20 kb/s, at the same time, the quality is practically equal to PCM. When the network is congested, we can either discard the LSB (the least significant bit) to reduce the average bit rate to 13 kb/s with a fairly good quality or store cells in a buffer, it can be output when the channel is free. The quality of speech coding is satisfactory if delay compensation is added.<>