The Optimization And Implementation Of G.729A Codec On DSP

The G.729 algorithm for encoding speech signal based on Conjugate Structure Algebraic Code Excited Linear Prediction (CS-ACELP) was proposed by ITU in 1996. Not only has it short code-decode delay but also provides good synthesized speech at 8kbit/s, therefore, it is widely applied in International Mobile Telecommunication ( IMT-2000 ), Personal Communication System ( PCS ), IP phone and handheld device. G.729A, which is a reduced complexity version of G.729, brings on 50% drop in its complexity without decreasing speech quality.How to optimize G.729A and implement it real time is the key problem.Optimizations have three aspects:(1) Algorithm optimization: The primary encoding parameters of G.729A are LSP parameters obtained by Chebyshev Polynomial method. It has a great deal of computation complexity and requires 668713 cycles. This paper proposes an effective and efficient algorithm AP-LSP ( Aitken & Polynomial LSP) using Aitken iterative method and polynomial synthesis division. It only requires 98484 cycles, which decreases about 7 times calculation complexity than before.(2) C language optimization: it includes overflow estimating optimization, loop unrooling, using inline and so on.(3) Compiler optimization: It has using intrinsics, choosing Oi, pragma, disabling debug etc.Throughout three optimizations, the calculation complexity of G.729A reduces from 590.097MIPS to 55.927MIPS, then the executing rate increases over 10 times.The DSP hardware platform is TMS320C5510 DSP, while software platform is...