The Studt of ILBC Speech Coding’s Key Technology and Its DSP Design and Optimization

In recent year, the techology of VoIP is deveoping quickly and becoming mature. Because of its advantages of low cost and technology, it starts taking on more of voice communication service. But the quality of voice constraints the development of IP phone. Inorder to increase the quality of voice and reduce the harm of packet loss during transmission on the packet switching network .In 2004, IETE published a new speech coding called iLBC(Internet Low Bit Rate codec). It from Global IP Solution is a royalty-free codec for Voice over IP (VoIP) network. It is the development of CELP(Code Excited Linear Predictive Coing). GIPS iLBC delivers speech quilty better than G.729A and equal to G.729E, while offering substantially better quality over congested networks with pack loss, becasue of adaptive codebook, packet loss concealment, voice enhancement. As compared to G.729 iLBC is a relatively new type of speech coding, so many manufacturers have not applied to the product with iLBC. It will be useful for practical application.The main work of this project is studying of the iLBC speech coding and its implementation and optimized on the DSP. Analysing of the basic principles of iLBC speech coding and its transport protocol in the RTP , compared to other VoIP coding. It focus on the frame in which the independent long-term prediction, packet loss concealment, the three key speech enhancement Technology. Analysing the basic principles of PESQ evaluation algorithm. It study the inner structure and the various peripheral interfaces of ADSP-BF533 chip. It chooses audio chip AD1836 and ADSP-BF533 chip to design the hardware platform on ADSP-BD533 EZ-KIT LITE. It basically develops the fixed-point C code of iLBC speech coding, tests the quality of fixed-point C code , and analyses the results .There is a gap of the end result expected from the best , it needs to continue to modify the code.