Design And Implementation Of Real-Time Voice Communication System Based On Android

In the wired network era, IP phone which took advantage of the technology of VoIP was all the rage. Having the advantage of low price, easy to use and stable performance, it accumulated a large amount of users and even shaked the monopoly of the telecom operators in the telephone business. With the development and popularization of3G technology, the mobile network is to gradually replace the traditional wired network’s status. Compared to IP phones in wired network era, IP phones in wireless network era have a huge advantages, it became IP phones that can be used anywhere getting rid of the shackles of the line.This paper describes the research status and development trend of the speech codec algorithm, explore the advantage of development based on the Android system, and do demand analysis for IP phones in mobile network are on these basis above, design an Android-based real-time voice communication system According to demand analysis, using AudioRecord and Audio Track subclass in Android multimedia framework to implement voice capture and playback capabilities, choosing G711and G729as voice codec standards under WIFI network and3G network respectively, using RTP as transmission protocol for real-time voice data, taking advantage of signaling control function of SIP to simulate call answer and hang up action in traditional telephone system During the actual development process, choosing G711and G729codec lib, Jlibrtp and PJSIP to implement voice codec, RTP data sending and signaling control function. At the same time, using two methods to optimize the implementation of G729algorithm to reduce the CPU utilization rate during the encoding and decoding process. Frist one is to make use of NDK to transplant C lib of G729to replace Java lib, in order to improve the efficiency of the algorithm Second one is to increase the search step of the algorithm, in order to reduce complexity and computation. After actual test, this system can meet the needs of real-time voice communication in aspect of function, cost and performance.