Dual Rate Speech Coder Key Technique Research

Low bit rate codec is one of the important aspect in communication technology. As a new voice compression standard, G. 723. 1 has good performance in both 5. 3 kbit/s and 6.3 kbit/s. This compression standard has great application prospect and commercial value. It is great significant to have a further study and turn it into real-time realization.In this paper, we present the fundamental principle of voice compression, codec mode, related standard in low bit rate voice compression and its develo'pment status. Then we devise a CODEC system, which is composed of DSP TMS320VC5509 and TLV320AIC23, to adapt to low bit rate codec. After studying the G. 723. 1 voice compression algorithm, we put G. 723.1 into reality in DSP. This system can be directly used in all kinds of multimedia communication system such as vision telephone or video meeting system. Considering its practical application, we also do some work in echo canceling. A BP algorithm is proposed to cancel the echo which is in telephone communication. This algorithm is based on Multi-Layer Liner Neural Network. All the work we have done make it possible to perfect this multimedia communication audio processing module.