Implementation Of G.729AB Algorithm Based On ARM Cortex-A9

With the rapid development of communication technique,the bandwidth resources become more important.It is a purpose for communication experts that how to implement a low delayed,highly compressed and robust voice codec algorithm in limited bandwidth resources.G.729 recommendation is a speech compressed codec algorithm,standardized by ITU-T in March,1996.The complexity of G.729 annex A is reduced compared to G.729 and a silence compression algorithm is approved in G.729 annex B recommendation.The coding of G.729AB speech codec signals uses Conjugate-Structure Algebraic-Code-Exicied Linear-Prediction (CS-ACELP) technique.The coder input signal is sampled at 8KHz,followed by conversion to 16-bit linear PCM.The frame is 10 ms.ARM Cotex-A9 is a new processor designed by ARM company,in which the strong ARM v7 architecture is adopted to increase the performance scalability and increase control over power consumption.This paper ports G.729AB speech codec to ARM Cortex-A9 and implements it according to the structure of ARM Cortex-A9 processor.Then G.729AB code is optimized using optimization techniques and tested with ITU standard sequences.The results show that the optimized methods increased the efficiency of G.729AB speech codec greatly in the end.Firstly,the history of speech codec technique is introduced briefly.Secondly,the detailed principles of speech codec key techniques are refered as the theory basement,including formula illation,linear prediction analysis,quantizaton,perceptual weighting,VAD,CNG and so on.Then the coding and decoding algorithm of G.729AB is analyzed.Thidly, the architecture and pipeline of ARM Cortex-A9 are introduced in detail.Lastly,we apply some C and assembly optimized strategies specializing for ARM Cortex-A9.Compared to the original C source code,the performance of G.729AB is improved by 80%,which satisfied the need of real-time.