Research On G.729A Vocoder Standard And Implementation On DSPs

The primary object of this paper is to implement the ITU G.729A 8kbit/s vocoder based on TMS320C5416 DSPs. 16 bit fixed-point ANSI C code is available from ITU but it is not suitable for implementation in real time using a digital signal processor(DSP) due to the large computational time required for the encoder and decoder. The most vitalest part of this paper is to convert the ANSI C codes into TMS320C5416 assembly language and hardware design required for G.729A implementation on TMS320C5416-100 DSK hardware object plat . The main tasks of this paper include: understand G.729A standard; convert the ANSI C codes into TMS320C5416 assembly language; program for hardware of TMS320C5416-100 DSK hardware object plat.G.729A is ITU Recommendation G.729-Annex A and is publicized by ITU in Nov 1996.International Telecommunication Union(ITU) established a scheme of G.729 speech coding in March 1996. The ITU G.729 recommendation contains the description of an algorithm for coding of speech signals at 8kbit/s using Conjugate-Structure Algebraic-Code Excited Linear Prediction(CS-ACELP), which makes use of Analysis-by-Synthesis and Code Excited Linear Prediction in the scheme and belongs to the newest, lower rate speech code of international standards established by ITU. The main aim of G.729A is to reduce computational complications. Mostly applied fields of G.729A include personal mobile communication, digital satellite system and high quality digital mobile wireless communication, etc.This paper detailedly studies the design and development of G.729A real time implementation based on TMS320C5416 DSPs. After discussing important techniques of speech coding and G.729A standard, firstly analyze ANSI C code of G.729A implementation, following to emphasis on discussing the software, hardware design and development of G.729A real time implementation on TMS320C5416 DSP. At last, analyzing the performance of the vocoder.The software, hardware design and development of DSP is core technique of G.729 A real time implementation. During software design and development, this paper emphasizeson transplant and optimization techniques of C code, such as file operation, assembly optimization, call of C and assembly function each other. The important questions are hardware interrupt programming, McBSP and AD/DA technique.This paper is organized as follows: Chapter 1 summarizes speech signal coding techniques. In Chapter 2 and 3, the speech coding rationales and G.729A encoder and decoder algorithms are discussed, respectively. Chapter 4 studies the software that defines this coder in 16 bit fixed-point arithmetic. Chapter 5 detailedly discusses the software. hardware design and development using TMS320C5416 DSP. This paper is summarized in the last Chapter 6.