Real - Time Multimedia Communication System Based On WebRTC Technology

VoIP gives us access to use SMS, voice and video to communicate with other people through Internet. And it facilitates and accelerates people’s exchange of information at a low cost. Nowadays smart mobile devices and mobile Internet technologies are blooming, especially after the emergence of 4G. All these factors are leading VoIP to mobile Internet. However, the situation of mobile Internet is dramatically different from the one of traditional Internet. The hardware of mobile devices and the network they work on is far more limited compared to computers or other traditional devices. Noises and echoes also harm the quality of mobile communication. WebRTC, which is developed and maintained by Google, is an open-source project aiming to offer a full solution to VoIP. Its internal media engines are capable of dealing with the collecting, recording, encoding/decoding and rendering of media data. And its performance under inferior network condition is still satisfactory, which makes WebRTC suitable for improving mobile VoIP. However, WebRTC’s support for audio codec and voice encryption are not yet complete. Therefore, a communication system based on extended WebRTC is proposed in this paper.First, WebRTC and its related technologies and platforms are presented, including the architecture of WebRTC, Android platform and common audio encryption algorithms. Then the design and thread model of WebRTC voice engine are analyzed. The work flow of voice engine is researched as well, with codec module and encryption module focused on, which are supposed to be the basis of voice engine extension. After that, an interface for audio codec G729A is designed and developed according to the WebRTC audio codec convention. Also, an encryption module is introduced and joins the work flow of voice engine. At Last, an Android communication system is developed based on the extended media engine of WebRTC.Experiments and tests are conducted for both voice and video functions. System control module and communication quality are tested. And essential parameters such as CPU load, bit rate and frame speed are collected and analyzed. The results show that the system can reduce bandwidth requirements while ensuring good communication performance. Meanwhile, noises and echoes are effectively suppressed.