G.729Speech Codec Algorithm Research And Implementation Based On ARM9

In modern voice communication systems,transmission efficiency and voice qualityare the research hot spots.Low-rate and high quality speech codec is in demand.G.729speech codec algorithm was established by ITU-T protocol (internationaltelecommunication union) in1996, which adopt a technology based on the ConjugateStructure Algebraic Code Excited Linear Prediction (CS-ACELP),a speech codecstandard with a8kbit/s bit rate. Because the speech quality coded and decoded byalgorithm is good, it has advantages of low encoding speed, high compression ratio anda small delay and so on. In many fields of IP Phone,camera phones, satellitecommunications and various multimedia communication systems, G.729has a verywide range of application.The main subject of this study is based on the ARM platform to realize the G.729speech codec algorithm. G.729speech codec algorithm with the much code is verycomplex. Even if the version G.729A is simplified, its algorithm complexity is stillhigh. How to improve the computing complexity and performance of G.729algorithmcoding and decoding in ARM platform, and how to take measures is the key of G.729algorithm realization in ARM platform. To realize the algorithm, this paper set up ahardware development platform based on ARM9, and system chips adopt themicroprocessor S3C2440A with low power consumption, low price and excellentperformance. In order to make whole design simpler, system use the UDA1341TSphonic acquisition chip which the Philips company produced, the chip which can linkthe S3C2440A through the IIS interface. This paper first introduced the G.729algorithm principle and relevance theory, including digital model of speech signal, theshort time domain processing, vector quantization, linear forecasting analysis and otherkey technology, on the basis of these making further analysis and understanding to theG.729speech codec algorithm and the source code. It analyzed the structure andfunction of S3C2440A and UDA1341TS, and designed the system hardware circuitbasing on this, detailed the interface and configuration between the voice capture chipand the main processing chip, and then introduced the software design of the hardwareplatform which has been set up, including the main program design and audio moduledriver design. At last in the reference of the delay and the storage space utilization ofG.729algorithm and in view of the characteristics of ARM9platform, it takes a seriesof measures to the G.729speech codec algorithm, including the C language level,assembly level and the algorithm level optimization, after optimization assessing andtesting the coding efficiency and the sound quality. The results testified that the optimalprogram can complete real-time codec.