基于SIP协议的视频通话应用的设计与实现.docVIP

摘 要 PAGE IV 摘 要 在公网下的移动通信中，目前大多数移动通话业务还是建立在2G和3G网络之上。在4G网络发展的情况下，通过4G及宽带公网下进行通话业务实现由很好的前景。换言之，4G网络和宽带下不仅可以提供高速率的数据业务，还可以通过4G及宽带网络下实现音视频通话。 在专网通信提出智慧融合宽窄带解决方案中，终端融合可以同时支持PDT集群、LTE专网、LTE公网、wifi四种制式，能够同时驻留LTE专网和PDT专网，按需随时切换。仅用一部终端设备，就能解决宽窄带通信问题。因此集通话、多媒体通信、地图等功能的APP而生。本课题主要研究通过SIP协议、SDP协议，开发一款在公网下安卓系统上能进行视频通话的应用。 SIP协议规定了呼叫建立和呼叫处理的流程。SDP协议则规定了两台终端媒体协商的过程。 用C语言开源的SIP协议栈PJSIP同时支持语音、视频，PJSIP在信令的建立过程中可以携带SDP内容，完成两台终端的媒体协商。 通过JNI编程安卓可以调用底层C库，调用PJSIP中的API，利用安卓编程实现整个应用。 关键词：SIP协议，呼叫，视频通话，PJSIP协议栈，安卓 ABSTRACT ABSTRACT In mobile communication, at present most of the calls are based on the networks of 2g and 3g. With the development of 4g network, the realization of service call under the 4g network and the broadband. In other words, It can not only improve the high rate data business, but it can also achieve the audio and video calls under the 4g network and broadband. In the private network communication proposed intelligent integration of narrow and narrowband solution, the terminal integration can support both PDT cluster, LTE network, LTE public network, wifi four standard, can also reside LTE network and PDT private network, on demand at any time switch The Only a terminal device, you can solve the problem of narrowband communication. So set calls, multimedia communications, maps and other functions of APP was developed. The project mainly research an application based on public network that can perform video calls on the android system. SIP agreement specifies the procedure of call set–up and call processing, While SDP agreement stipulates the negotiation of two terminal medias. Under the open source of C-language, SIP agreement and PJSIP support audio and video at the same time. With the process of establishment of the signaling, PJSIP can carry the content of SDP, complete the negotiation of two terminal medias. Through JNI programming, android can invoke the underlying c library and the API of PJSIP，realize the whole application by taking advantage of the android p