Design And Implementation Of Mobile Multimedia Application Based On Android

With the rapid development of Internet technology and multimedia technology, multimedia applications have been greatly popular. They are not only integrated into every aspect of people’s lives, and even changed the way people live. In order to meet the growing demand and improve the flexibility of software, the loading terminal is developing towards a portable terminal. In recent years, the development of mobile Internet and smart phones is very fast. It makes the development of application based on smart phones possible.This paper designs and implements a mobile multimedia application based on Android. The software runs on the Android operating system for smart phones. It completes audio and video session establishment, task messaging, voice calls(VoIP), real-time video uploading and playback functions. It can meet the requirement of the people on a wide range of information exchange basically. And it can be used in emergency dispatch, distance learning, mobile security and other systems. The main contents are as follows:(1) In order to lay the foundation for software development, this paper analyzes the Android application development technology and software development of the key technology involved. According to the functional requirements of the system, this paper designs the overall system framework and software framework in detail. On this basis, it designs the SIP signaling interaction processes of each module, and uses appropriate technology to achieve the various functional modules.(2) Aim to achieve SIP signaling interaction and realize the transmission of audio and video, this paper transplants open source libraries such as Mjsip and Jlibrtp. For the purpose to improve the efficiency of the software, it combines the Android NDK technology and Java JNI technology to implement the codec of video data by porting the open source library of FFmpeg. In addition, it implements the voice data codec through G.711 voice codec standard.(3) To improve the fluency of audio playback, this paper sets up a data cache and deals with packet loss by loss detection and insertion of duplicate packet. In order to improve the real-time video playback quality, it uses a steady contracting strategy in the video sending end and implements a secondary cache to sort packets, group packets and handle packet loss in the video receiving end. Besides, for the purpose to improve the efficiency of video coding, this paper studies the H.264 intra prediction coding techniques. This paper selects an intra prediction mode based on the flatness of the picture macro blocks and the correlation of adjacent sub-blocks. It optimizes the video encoding library and improves video coding efficiency.The tests for completed multimedia application software show the software works well. It is able to complete its intended function.