Design And Realization Of Frame-Rate Control In Wireless Video Surveillance

Video surveillance based on wireless network is the latest development direction of video surveillance system. After video informationfrom recorded by the camera is issued to wireless network, wireless video system can make people who stay far away from the scene watch and control the scene with a wireless online personal computer or mobile internet device. Compared to traditional wired video surveillance, wireless video surveillance is more flexible and motorized, and lower cost, more simple network and easier maintenance. Therefore, how to improve wireless video surveillance should be a focal and hot point to be discussed.This paper discussed the history, advantage and actual application of WiMAX standard, and presented the key technologies in the physical layer and MAC layer for WiMAX standards. This paper also discussed the principle, feature and application of H.264 standard, and a mobile video surveillance system based on H.264 is presented in this paper. A brief overview of H.264 CODEC solutions is presented. This paper discussed the principle, feature and application of video surveillance. Then the project of video surveillance and wireless transfers was introduced in detail. This paper discoursesd on the video transmission problem over wireless environment, including Video frame loss seriously appearance, video speed excessive increase appearance and video pause or blank screen appearance. Therefore, how to build a mechanism to improve those issues will be discussed focally in this paper.In dealing with the instability of wireless network, this paper proposes a method to improve the video fluency, using video frame-rate control. This paper first introduced related parameters of the method, including video buffer, present video frame number, network status parameter, video acceleration threshold, video deceleration threshold, time delay frame number, video frame rate, video standard frame rate and video frame rate variation. Then the principle of the frame-rate control method is presented, and this paper also discussed the detail related, including frame rate variation issue, no video frame in buffer issue, network status issue and network interrupt long time issue.Through the video surveillance application based on wireless network, this paper tested the real effect of the mechanism, then introduced the hardware and software environment of the test. In the following the paper described the test procedure and finally gived out three different test results. No matter the network status is good, medium or bad, through the debug log file of the test software and the statistics of the related data, the practice proves that the frame-rate control method improved the video fluency and decreased the influence of network instability, and the method is feasible and true.