Embedded wideband speech codec based on ACELP and TCX

Packet loss and packet delays due to packet switching on IP nets affect speech quality.This paper presents an embedded wideband speech codec which is one candidate for the G.VBR proposed by the telecommunication standardization sector(ITU-T).The codec divides an embedded bit-stream into five layers with bit rates from 8 kbit/s to 32 kbit/s.The first three layers are coded using the algebraic code-excited linear prediction(ACELP) coding technique while the last two layers are coded using the transform coded excitation(TCX) coding technique.When the current frame information is lost,the lost information is recovered from classification information and coded parameters in the previous frame.Tests by ITU-T show that the codec meets the ITU-T requirements.