Research And Application Of Visual VOIP Technology On Android System

As the rapid development of Internet, the need from people of real time information and vivid and abundance content has become expanded. Thanks to the innovation and advance of computer science and communication engineering development in recent years,3G/4G technology becomes popular, wide band network is growing fast, real time protocols turn to be more mature, hardware facilities of network and mobile devices run more effectively, and all of them provide possibilities to implement multimedia voice/video communication. In this background, video phones based on VOIP have numerous advantages, such as cost lower, easy to expand and support various businesses.The visual VOIP phone that is designed and implemented in this thesis is based on the most popular mobile device OS——Android. Its openness, compatibility of hardware and the good flow make Android occupy the unshakable status in mobile intelligent terminal operating systems. This video phone is based on A13hardware platform, which is a specific mobile hardware solution to support multimedia communications. The innovation of this phone lies in making full use of Android’s support for hardware, adding H.264hardware encoder to improve the performance of system efficiency. Moreover, to make the product more practical, speech recognition, multilingual support and multiple screens support are added to help expand the application fields of product and the availability of hardware equipment.This thesis not only introduces the Android’s upper application framework, but also comprehensively expounds the development process of the NDK, how to call third-party libraries, as well as analyzes from the underlying native code to the JNI interface and to Activity in application layer, and illustrates the hierarchical relationships among them and the key technology.The security of system cannot be ignored under the mobile Internet rapid development trend. Android’s openness is convenient for the developers and users, but there is also a great safety hidden trouble. At present, almost everyone participates in a variety of social and communication applications. However, those applications are more or less involved in the users’ privacy. This paper has done deep study on the Android security mechanism, such as the sandbox mechanism and digital signature mechanism. And especially for video phone, the security of multimedia data is analyzed. Audio/video streamer in visual VOIP phone is transmitted through RTP/RTCP in clear text, so that they could be easily intercepted in the network transmission and leak communication content. Consequently, to ensure the safety of the RTP transmission, SRTP method is adopted in the video phone. SRTP is a good supplement for RTP, and provides confidentiality, message authentication and replay protection.