Research On Anti Packet Loss Algorithm Of G.729Codec And Its Implementation On ARM Platform

Real-time speech communications in operations are facing the packet-lossproblems result from network congestion, channel disturbance and so on, theseproblems are making severe quality degradation to the received speech and theseproblems are far away from being solved. Therefore the reliable transmission of speechon the Internet has gained much attention.G.729speech coding algorithms is commonly used in speech communication.Multiple Description Coding (MDC) is a source coding technology with whichinformation can be transmitted in unreliable networks. Based on these, the principle andalgorithm of reliable G.729speech transmission are studied and its anti packet lossalgorithm based on Multiple Description Coding are investigated in the thesis. Antipacket loss algorithm of G.729codec uses two descriptions scalar quantizing algorithmand interleaving algorithm to achieve. Anti packet loss G.729speech codec algorithmsof high computational complexity, while the computational performance of the ARMprocessor is limited, without the optimized G.729speech codec is unable to meet thedemanding real-time speech communication service. For the ARM platform, codecdepth optimized to improve the real-time, and port to the ARM-Linux platform. Finally,the speech codec complexity and speech quality are to be tested. Anti packet lossperformance is tested in the channels suffer from packet losses simulated by NIST net.The results have shown that, G.729anti-packet-loss algorithm studied in this thesisis obviously better than none anti-packet-loss algorithm. The computational complexityof the algorithm on ARM platform is reduced to about one fifth of the original. Theseprovide anti-packet-loss G.729speech codec with a high real-time for ARM platform.