itut g.729a协议的研究及其实现-research and implementation of itu g 729 a protocol.docx

茎茎塑至
ABSTRACT
With the rapid development work and IC technology,the
work mainly basing on munication es the world’S ,the great ess of makes IP e the backbone technology of the futln'e the essful development and application of IP telephony foreshow the appearance of the new work
basing on IP.
This thesis mainly studied the mendation and its annex A(G729A)
among the above mendations.
The characteristics of G729 were contrasted with the most speech signal coding
mendations at first,and then analyzed the characteristics,analysis methods, digital models and different speech signal coding it,the algorithms of G729 and G729A were also contrasted in order to show how the
CS—ACELP algorithms are simplified in the following chapteg the fixed point ANSC C simulation programs G729A using VC++ Was analyzed and studied, and great emphasis Was put on the functions and the end ofthe thesis,the research actuality of the improving schemes of the coding of speech signal inside and outside the country were summarized,and brought forward the suggestion that it Can
improve the coding algorithm of the speech signal by improving the quality of speech signal and shortening the delay of the an improving implementation
scheme of fast searching for the codebook of G729A was bring forward,In which,the sequence of codebook search is reordered according to the criterion of mean squared wei曲ted error between target vector and filtered adaptive codebook vector,and the algebraic codebook iS searched until a predetermined threshold iS satisfied.
Key words:speech signal coding,G729,Ca729A,codebook
IT
l绪沦
1 绪论
IP网络电话将成为重要的通信业务
IP网络电话由于具有以下所述的许多独特的应用优势而在近年里得到迅猛发
展111:
】)价格低廉价格低廉,尤其是国际长途呼叫和传真具有明显的价格优势。这是IP电话进
入市场的首要因素,其根本原因一是口电话均采用压缩语音编码和分组统计复用, 带宽利用率高;二是IP运营商都是采用租线方式运行,其成本核算和计费方法与传统电信运营商不同。
2)可以灵活地提供各种增值业务价格优势是IP网络电话进入市场的原始推动力,而增值业务才是IP电话得以
发展的真正动力。由于IP电话都是智能终端,IP网络是丌放式网络,其