Research On Synchronization Of Audio And Video In The Vehicle Video Surveillance System Based On 4G Mobile Network

With the rapid development of Internet,information processing and communications network,information networking in the industries have been promoting.Streaming media applications based on 4G mobile network have been popular.Multimedia synchronization is a special and important indexes of quality of service(QoS)of multimedia applications,the quality of the multimedia playback,real-time interactive and capture of multimedia information,are affected by the QoS of synchronization.Synchronization control technology is one of key technologies of streaming media applications.Network delay and jitter,end-system delays and jitters,clock drift and clock skew,capture and encode with different hardwares and encode algorithms between audio and video,are key parameters which affect the synchronization between audio and video.Based on the research of the synchronization mechanisms and existed solutions of the streaming media systems,on the basis of the requirements on the audio-video synchronization in the vehicle video surveillance system based on 4G mobile network,an audio-video synchronization solution based on RTP/RTCP is proposed.To guarantee the audio-video synchronization,collaborations between sources,network and sinks must be carefully designed to provide relevant synchronization mechanisms respectively.At the source,the relevant control mechanisms are provided for ensuring that capture,encode and transmit of audio and video synchronously.The encode bit rate or frame rate,transmitting velocity will be adjusted,according to the feedback information from the sink,to be adaptive regarding changes of network conditions.At the sink,the audio as master stream and the video as slave stream,synchronization within the audio stream is achieved by the buffer control mechanism which tries to avoid receiver buffer underflow and overflow problems.Synchronization between audio and video is achieved by the comparison between the timestamps of the audio and the video frame and restoring synchronization by means repeating or dropping the video frame.The solution is implemented in the vehicle video surveillance system based on 4G mobile network.It is shown through the test results that the proposed solution provides high-quality synchronization performance between audio and video streams.