Research And Implementation Of Audio Echo Cancellation In Video Conference System

With the development of science and technology and the growing needs of convenienceand community, the traditional single-media communication services such as telephone, fax,has been difficult to meet people’s needs. Video conferencing puts video, audio, text and othermedia information presented in front of people transcend in TCP/IP protocal, and bring agreat convenience and real-time communication. However, it is critical to guarantee thequality of Audio to ensure the quality of Video conferencing.In addition to the requirement ofthe voice clarity,voice quality also requires high real-time,and at the same same requires thesynchronization of audio and video To ensure that the voice clarity, the most critical issue is toremove the effects of echo and noise.Especially the existence of the echo, often the voice onthe video conferencing system the most obviously, Compared to noise, the volume of thevoice is much larger. Thus, to ensure the voice quality of the video conferencing system mustadopt a set of audio processing including echo cancellation, noise suppression, efficient audiocodec, voice mixing process. Each section in this process is often not independently, and theyinfluence each other, inseparable, so this set of process is often to solve as an entire system.In this paper, in the development practices of video conferrence system, it introduces thecomplete implementation of the echo cancellation module of video conferencing, and alsointroduces the implementation of the audio mixing module and audio and videosynchronization module which are closely related to the development of the echo cancellationmodule. All the modules are realized based on Directshow Framework. The functionsincluding echo cancallation,audio mixing and audio and video Synchronization are packagedin Filter.One filter is responsible for one function,the way of data share amony filters ismemory share amony processes. The overall architecture design of echo cancellers is of betterintelligibility, scalability and module independence, it has achieved good results in practicalapplications.At the same time,in this paper the echo cancellation modules in the application of videoconferencing systems has been tested. And the software echo cancellation effect parametersand environmental factors has been verified by testing Judging the echo cancellation effect, itis not only by subjective feelings, but also combining with a number of performanceparameters which theoretically prove wheather the echo cancellation effect is good or bad.In this paper, it combines the research of echo cancellation and development practices ofvideo conferencing systems to solve practical problems. It is of high practical significance.