Implementation Of G.728 Speech Coder Based On TMS320C64X

It is necessary to make low-rate speech coder resolve the limit of broadband resource with the very fast development of digital mobile and multimedia communication. As the harvests, there were a lot of mide-low rate codecs based on both parametric and mixed-codec presented by scholars. Those are the basic of the ITU new recommendation for speech codec. It is very important for those harvests applying widely and quickly. G.728 recommendation that is schemed in 1992 is a speech coder using code excited linear predictiori(CELP). With the low-delay code excited linear prediction(LD-CELP) technique specified in G.728 recommendation, 64kb/s PCM speech bit stream will be compressed into 16kb/s and then be transmitted in the communication network. The basic processed data is speech block that includes five samples. When sample rate is choosed 8kHz, the delay of the algorithm is only 0.625ms and delay of a speech line less than 2ms. The algorithm is too complex to be realized on low performance processor platform. With very low delay introduced, good quality of reconstructed speech and good quality of transition, LD-CELP is suitable for long-distance and mobile communication networks with time delay sensitivity.In recent years, the digital signal processing is developed fastly by the progress of manufacture technology of very large integrate circuit. Here, the TMS320C64X DSP is chose as hardware platform to realize the codec in G.728 recommendation. This thesis is organized as follows.In this paper the technical of speech coding DSP are first introduced briefly, then the reasons for choosing LD-CELP as task are stated. The basic technology for speech coding and the principle and implementation technology of LD-CELP are then discussed in details. The C code is optimizing for TMS320C64X DSP platform to achieve real time need. At last, a software simulation on PC platform and hardware simulation on EVM board are carried out.