The Research Of Key Technology And Software System On 4G-based Vehicular Video Transmission

The existing vehicle wireless surveillance system supports up to SD resolution with low frame rate (704×576, less than 15fps), which cannot provide image with high quality. Real-time HD video (1920×1080,25fps), with a large amount of data and significant increase of transmission rate, puts forward higher requirements. Hardware upgrade, network bandwidth, software structure and transmission improvement should be considered seriously. Among these factors, software system design and network transmission optimization are key points to implement 4G vehicle HD video surveillance system in this paper.This paper describes the key technology and the overall architecture of the system. In the process of transmission, RTSP and RTP are used to control and transmit media data. On the server side, circular-queue buffer is applied to smooth video stream and reduce the inpact of transmission fluctuation. On the client, MFC-based interface design is applied, embeded with libVLC library for video related functions, as well as the use of multi-threading and messaging to coordinate control function. Finally, both server and client software are implemented. The actual test, by evaluating video quality, transmission delay, resource consumption and other items, confirmed that availability and effectiveness of the system could meet demands.Due to the bandwidth instability of wireless network, packet loss is inevitable. Besides, in order to solve the big delay problem brought by traditional RUDP, which was implemented on the application layer, a part-reliable-datagram UDT protocol (UDT-D) is improved to refine video transmission, taking replacement of retransmission mechanism with packet survival threshold. Actual tests in different environments, adding mobile data cost as evaluation item, proved that UDT-D can effectively control delay and improve transmission quality.In this paper, a kind of 4G vehicle HD video surveillance system was designed and implemented, which is versatility and ease of use. And in order to solve transmission problems, lots of efforts have been spent on the improvement of transport protocol. All outputs confirmed that these works are of high theoretical and practical value.