| In recent years, with the sustainable development of national economy, video surveillance technology has been widely used in many areas, such as government, health care, education, entertainment and public transit. Since the traditional video monitoring system is mainly based on the cable network monitoring and it has some shortcomings, such as the complexity of system wiring, the high cost of laying and less flexibility, so it is unable to meet the needs of the people to monitor at any time and anywhere. With the continuous development of wireless network technology and the unceasing enhancement of the hardware level of smart phones, the mobile video surveillance system shows a great competitive advantage in the practical application. Based on the Android platform, the implementation process of mobile video surveillance system are studied in this paper.Some important parts such as video coding, video transmission, group packing,video decoding and video broadcast in the mobile video surveillance system, have been introduced in this paper in detail. Firstly, differing from the traditional video monitoring system, the mobile video surveillance system need the wireless network for data transmission. Due to the limited wireless network bandwidth and the poorer stability, coding standard h.264, of which the image compression ratio is higher and network adaptability is strong, is adopted for the system. Secondly, the data transmission in the traditional way is to use RTP protocol and RTCP protocol for data transmission. Because the way to realize transmission is more complex, the custom general header structure is used in order to reduce the complexity of the video data transmission. Then, in order to improve the efficiency of the video monitoring, the UDP protocol is used as the transport layer protocol of the system. Since the UDP protocol is unreliable transport protocol, the packet loss phenomenon will inevitably appear in the process of data transmission. However, the detailed processing of packet loss phenomenon is carried on so that it can avoid the phenomenon of the flower screen or caton images caused by the data packet loss. Thirdly, for the decoding process of video data, it has been a tendency in the Android system that OpenCore, the multimedia processing control, is replaced by Stagefright which have less support file format and unstable faults. What’more, Compared with multimedia processing engines for Android system, FFmpeg has the advantages of cross-platform, stable framework, and file format supported, so FFmpeg is adopted to decode the video data. In this paper, the detailed explanation is also provided for the compilation of FFmpeg. Finally, the video data for this system is processed by being divided into historical video data and real-time video data. In order to avoid the thread block due to the UI thread frequently updating, the logical operation which is time-consuming is taken in the child thread.In this paper, the proposed of mobile video surveillance system based on the Android platform can satisfy the actual project requirements and has a good monitoring effect in practice. |
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