Based On The Android Mobile Voip Hd Video Phone System Design And Implementation

With the development of mobile networks and the popularity of smart phone in recent years, VoIP services which based on smart operation system(OS) are gaining increasing concern by many carriers and corporations. Compared with traditional VoIP services, mobile VoIP in support of smart mobile terminal, could provide more complex multimedia services, users also want to enjoy the convenience and fun services like smooth video, instant messaging, Hi-Fi calls, etc. Therefore, in view of the current demand, the study of VoIP applications based on smart OS has a very important significance.An Android VoIP application of high-definition video phone is designed and imple-mented, the application supports instant messaging(IM), online notification Hi-Fi voice calls, HD video, and contacts. With the Android application development technology, system is in collaboration with a variety of network protocols; supports a variety of speech coding standard and H.264video coding standard; deals with the voice problems caused by characteristics of wireless network to assure good voice quality; designs a beautiful user interface with the consideration of user experience and habits of operation.The SIP Stack Android built in hasn’t open enough interface for development, so the third-party SIP stack Jain-Sip has been transplanted and helps to implement IM, video phone and other scalable SIP service with its full interface for sip service.To cancel the acoustic echo in IP phone, Speex Echo Cancellation(EC) Library has been transplanted and uses prefetch with the Android NDK technology. To make play and record thread be synchronized, a prefech variable method is taken and enhances the EC effect.Based on the research of video encode/decode solutions, with the help of Android OpenCore media framework and UNIX domain protocol socket, the H.264data which encoded by hardware could be captured in consideration of high power consumption and more CPU resources occupation by software encode. As for video decoder, the tailored FFmpeg library has been transplanted to decode video by H.264codec.Application has reached the aim of wireless real-time HD video call and also has a good test report at packet loss rate, voice quality, video fluency, etc. The design of the application could be a reference for other Android VoIP application developers.