Design for New Kind of Low Rate Speech Codec in VoIP

An efficient low rate Speech Codec can get well utilized to solve the problem of network congestion under the circumstance of current network. To the speech characteristic analysed, the voice activity detection (VAD)algorithm that is much fewer operational quantity and very effective is designed based on conjugate structure algebraic code excited linear prediction (CS-ACELP),the Speech Codec in this paper is implemented on the Digital Signal Processor(TMS320VC5410)with low bit rate and good timbre. That will lower down the average bit rate to about 4kb/s. As a result, the demand of real-time full-duplex communication in VoIP is fulfilled.