Optimization Of G.723.1 Speech Codec Based On MCF5249

The application of a speech codec mostly depends on its running time and compressed speech quality.G.723.1 is a stardard of dual rate codec algorithm produced by International Telecom Union (ITU-T). The recommendation specifies a coded representation that can be used for compressing the speech or other audio signal component of multimedia services at a very low bit rate as part of the overall H.324 family of standards.The realization language of G.723.1 is ANSI C which is available from the ITU.Because of ANSI C, G.723.1 codec can be applied to any C develop- ment kits, but is not specially developed for a certern CPU or DSP.So it can't use resource within the CPU or DSP efficiently, such as eMAC. This will result in needing plenty of running time and low efficiency of the G.723.1 codec, and be not able to get good result we want.MCF5249 is a powerful and costless microprocessor produced by Motorola Corporation.In order to develop a VoIP voice communication system based on MCF5249 and G.723.1 codec , it needs to optimize G.723.1 C code.Our purpose is to get best compressed speech quality through least instruction cycles.This paper studies the principle and algorithm of speech coding in depth , then analyses the whole G.723.1 algorithm and code.According to the MCF5249's characters, the paper points out the optimization method on algorithm and assembly for each function. Using profile tool in VC++ tests the validity of optimization algorithm code; using MCF5249C3 development board and CodeWarrior Integrated Development Environment test the application of optimization code.Finaly we achieve our purpose cutting down G.723.1 speech codec's running time at most .After evaluating its MOS value , G.723.1 speech codec's score can reach 3.4.