| Video surveillance system, which is an important element in the area of monitoring,has been the hotspot. Because video surveillance system with rich information, intuitive,convenient, etc., it has been widelyused. In all walks of life, you can see all kinds of videosurveillance systems. Little to our daily lives, such as in supermarket, bank, transportationcrossroads, companies, etc., there are always some cameras in the surveillance. Large toelectricity, finance, oil, port, water conservancy, shipping, military, firefighting, the videosurveillance system is playing an important position. In modern society, as theimprovement of social information, there are more and more fields needing the videosurveillancesystem.Mobile video system is one kind of video surveillance systems. It is the thirdgeneration of the video surveillance, with high integration, low cost, small size, easyinstallation, flexibility, and easy to carry, etc., so it gets more and more widely researchedandapplied.Inrecent years,embeddedsystemandwirelessnetworkmakethemobilevideotechnologypossible. The monitor can move freelywith the real-time monitor, onlyholdingterminalsofmobilevideosystem.This paper has developed a mobile video surveillance system based on ARM9S3C2440. It has manyadvantages, such as strong real-time, portable, high integration, easyinstallation,flexibility,cost-efficientandsoon.According to the characteristics and requirements of mobile video system, this paperdetailed designed the hardware and software architecture of the mobile video system. Onhardware architecture, through the research and analysis of the system and electronicsmarket, according to the performance of various types of electronic devices, cost, targetedselected the relevant chips, devices, and so on. Embedded microprocessor chip uses ARM9S3c2440, video acquisition chip uses zc301, wireless transmission chip uses zd1211b, theplayer uses 3.5-inch LCD, as well as other relevant external circuit components, such as Flash, RAM, etc.Thenthis papermadetheoverall hardwaredesignonthesespecifications.On software architecture, this paper made the overall software design, selected theembedded Linux as the operating system, designed the kernel and root file system, and ontop of it carried out a detailed overall design of the software to meet the various features ofmobile video, making full use of a number of open-source spirit, such as V4L , FFmpeg,SDL,RTP,etc.This system design is based on ARM9 S3c2440 embedded platform, which is therepresentative processors of ARM9. It has many advantages such as stable frame structure,mature technology, data and information-gathering and other aspects, so it is the preferredchoice in the embedded video monitoring system. Embedded operating system is the coreof the software system. This paper chose embedded Linux as the operating system, usingthe latest 2.6.29 kernel and YAFFS as the file system. It has open-source and supportingmultiple hardware platforms, and many other good features, so it is easy to be researchedanddeveloped.The mobile video system has two parts-sides, video capture side and monitor side.Generally speaking, there are always several video capture sides to collect the video, andonly one monitor side to monitor the capture video. In video capture side, at first, itinitializes the hardware and some software settings, such as the collection points and thechannelnumberandsoon.Afterthat,itcollectthevideobyzc301,thenthecollectedvideodata are compressed by the microprocessor S3c2440. Finally, the compressed data will bedelivered by wireless transceiver device zd1211b. In monitor side, it is the capture side'sinverse process, also need to select the channel number that the selected monitoring pointsyou want to see. Then the side will receive the compressed video data byzd1211b, throughthedecodingbythemicroprocessorS3c2440,videocanbeplayedonthe3.5-inchLCD.This paper designs and develops the application software in detail. Through theanalysis and Summary based on many experiments, the video capture side was designedwith double thread, collect the video and encode the collected data by the same time.Besides, the monitor side has one thread to meet the functional requirements. In addition,for the USB Host/Device port issue, this paper designed the scheme of switching options,the scheme not only makes the system meet the system's R&D needs, such as burning embedded Linux kernel and file system, the entire system's backup and restore etc., butalso support the work of the final system's requirements, using video capture devices andwirelessequipmentatthesametime.Video codec directly impact the fluency and visual effects of the video. So choosingwhich encoding standard based on ARM9 embedded platform is particularly important.After brieflyintroducing some of the current video codec standard, do a lot of experimentsby the FFmpeg, an open source solution, then contrast and analysis with the data from theexperiments. At last, chose the MPEG-4 encoding standard for the mobile video system,whichnotonlyguaranteeabettervideoquality,butalsohasagoodreal-time.During the research of video codec, found that H.264 has a high performance.Although because of its high complexityit is not used in the mobile videosystem, but withthe development of embedded, H.264 will has a good future with embedded system. So inthispaperalsodidin-depthstudyonH.264basedonembeddedsystem.After a brief introduction of the H.264 coding standard, this paper transplant it onARM architecture platform, and chose the algorithms grade and parameters for the ARM9embedded systems, to make H.264 consociate the computational complexitywith the videoqualityontheembedded platform.Andthispaperproposesanewmotionestimationsearchalgorithm, multi-triangle search, which is optimized for embedded systems. Although thereare still some defects in the optimized algorithm relatively, but the optimization to H.264reducethecomplexityofthealgorithmandthecompressiontimegreatly,underthepremiseof the certain quality and bandwidth. The optimized algorithm is more suitable forembeddedplatforms. |
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