The Itu-t Of G.729a Voice Coding Algorithms

With the rapid progress of internet and morden mobile communication, the bandwidth utilizationand speech quality are becoming the main problem. The valid approach to solve this problem is low rate, delay, loss and high quality codec. To meet such requirement, ITU-T has enacted G.729 protocol in 1996. The 8kbit/s speech coding algorithm conjugate structure algerbraic code excited linear prediction (CS-ACELP). G.729A is the reduced-complexity version of 8kbit/s speech coding algorithm G.729 standardized by SG15 of ITU-T. The algorithm structure of G.729A is the same as that of G.729 and the bitstream of G.729A is interoperable with that of G.729. The speech quality produced by G.729A is equivalent to that of 32kbits/s ADPCM for most operating conditions, achieving the request of long-distance telephone.In the first chapter, the classification method and evaluation standard of the digital audio coding algorithm, digital audio coding standards in existence, the developing tendency of the digital audio coding algorithm are introduced.In the second chapter, the compression theory of G.729 describes the special methods such as linear prediction, vector quantization and codebook searching. In the third and fourth chapter, describes the development support platforms used for FreeScale Coldfire family.MCF5249. Analyses how to achieve the G.729A standard in MCF5249 and how to achieve the integrated calculation with C and assemble language in MCF5249. several software optimization techniques are presented for efficient implementation of G.729A standard.By researching principle of G.729A coding algorithm and optimizating software, The computational complexity of the optimized G.729A algorithm has been reduced to 1/13 that of the original algorithm. The experiments show that the output speech has the high reconstructed speech quality with the optimized G.729A algorithm.