Network Video Surveillance System Based on Embedded Linux and ARM Technology

Transcription

1 Network Video Surveillance System Based on Embedded Linux and ARM Technology Abstract Feng Zhou Information Engineering Department, Suihua University, Suihua , China With development of computer information technology, the network video surveillance system has been widely used in all fields, and attracted more and more attention. In this paper, one network video surveillance system based on embedded Linux system and ARM technology is presented. The system uses a USB camera to capture the video images and can compress and pack the original video image data. The processed data is converted into data streams according to TCP/IP protocol, transmit through Ethernet, and the original video images can be displayed on terminals, realizing long-distance network video surveillance. Keywords: Embedded, Linux, ARM Technology, Network Video Surveillance System. 1. BACKGROUND 1.1 Introduction The video surveillance system can reflect the characteristics of the monitored object vividly in real time for analysis. It is widely used in many fields such as bank monitoring, production management, traffic safety and so on (Chen and Fan, 2014). In particular, the rapid development of computer information technology has led to an increasing demand for network video surveillance systems. The traditional monitoring system realizes monitoring through signal simulation, and has many limitations. After simulation of image information, the information is vulnerable to damage, and the quality of simulated image is low. The cabling project of traditional monitoring system is huge, difficult to meet the monitoring requirements in the transmission distance, and the data query is cumbersome, featuring low stability and reliability. For these disadvantages, the traditional analog signal monitoring system has been eliminated (Xie and Wu, 2013). With the development of computer information technology, the monitoring system is improved and optimized. With embedded technology and ARM technology, the stability and reliability of the network video surveillance system is greatly enhanced with increased surveillance range, effectively making up for the shortcoming of the traditional signal simulation monitoring system (Han et al., 2013). The network video surveillance system based on embedded Linux and ARM technology features stable, convenient installation and maintenance, and modular design, which are also the research direction. 1.2 Purpose This paper studies one network video surveillance system based on embedded Linux and ARM technology to make up for the shortcomings of traditional signal analog monitoring system, so as to improve the network video surveillance system. In view of this, this paper studied the key technologies of this network supervisory system in depth, including embedded Linux, AMR technology, data acquisition and image data compression. The system uses network resources efficiently, and does not require additional equipment, realizing long-distance video surveillance. This system has good scalability/flexibility and low cost, and the installation, maintenance and management is convenient. This system can be applied to remote network monitoring of banks, key laboratories, communities and schools, as well as real-time monitoring and management of production process and medical equipment, with high application value and reference value. 2. OVERVIEW OF NETWORK VIDEO SURVEILLANCE SYSTEM BASED ON EMBEDDED LINUX AND ARM TECHNOLOGY The network video surveillance system based on embedded Linux and ARM technology composes of hardware/software components. The hardware components include peripheral interface circuit, supporting 132

2 hardware and embedded processor. Of which ARM9 embedded processor is a core part. Samsung S3C2410 ARM9 embedded processor is adopted, connected with SDRAM chip and NAND Flash controller, and is the critical control core and storage center of the system. The processor resources are expanded and allocated in the system (Cai, 2014). The embedded processor contains two HOST/DE-VICE USB ports, a serial port, an Ethernet expansion port and a JTAG port. The Ethernet expansion port is connected with the Ethernet control chip CS8900A. Via the JTAG port, the applications, the embedded Linux operating system and Flash memory are connected (Shi et al., 2015). The camera is mounted at the two HOST/DE-VICE USB ports. This system will send the video image data captured by the camera to the Flash memory for storage. The JPEG compression processing program will compress the data in Flash memory buffer and store. The captured video image data is stored in NAND Flash and ready to receive the access from the remote host. The system can send the stored video data directly through the Ethernet expansion port of the Ethernet controller chip CS9800, and the control host in the remote terminal will receive the video data (Du and Cao, 2015). The software of the system consists of three parts: image data JPEG compression, video image data acquisition and network communication. Figure 1 shows the hardware structure diagram of network video surveillance system based on embedded Linux and ARM Technology Figure 1. Hardware Structure Diagram of Network Video Monitoring System Based on Embedded Linux and ARM Technology 3. IMPLEMENTATION OF NETWORK VIDEO SURVEILLANCE AND COMPRESSION OF IMAGE DATA First, load the USB camera driver. Then write the application for video stream acquisition. Video4Linux contains program interface functions for all I/O interfaces of the camera so as to control the I/O interfaces (Wang and Peng, 2015). To write Video4Linux acquisition program, define the data structure first, containing the basic data captured by the camera, all data relevant to the capture area, attribute information of all data sources, all attribute information of the image data captured by the camera, memory mapping data and all input frame information within the camera storage buffer, etc. (Qiao and Li, 2015). 3.1 Start of video acquisition device The open function will be called in the embedded Linux system to start the video acquisition device. If it is displayed that the open function is called successfully, the descriptor of the returned file is vd fd. If it is displayed that the call of open function fails, the descriptor of the returned file is vd fd-1. We can write the following implementation program if((vd fd = open(vd videodevice, 0 RDWR)) 1) exit fatal(error opening V 4L) (1) 3.2 Collection of device and image information The collection of image video data and device status data acquired by the camera can be performed using the control command VIDIOCGCAP in the ioctl function, and the collected image video data and device status data can be stored in the video-capacity structure (Song, 2015). The specific program is 133

3 if(ioctl(vd fd, VIDIOCGCAP, &(vd vi deocap)) = 1 exit fatal(error get videode vice capacity) (2) 3.3 Setting of camera image parameters Before image data acquisition by the camera, modify the image parameters and resolution of the camera and other parameters in accordance with the performance of the system and the requirements of designers. Assign new value to each component of the program, and then call the function icotl(-fd, VIDIOCSPICT, & picture) (Xu et al., 2013). For example: picture. color = 65256; picture. depth = 4; if(icotl(_fd, VIDIOscpict, &picture) < 0) {perror(vidiocspict)return 1} (3) 3.4 Video acquisition After the above initialization is completed, the video image data acquisition by the camera is realized. In general, there are two methods for video image data acquisition: read (reading) and mmap (memory mapping). Compared with read method, mmap method conducts mutual mapping between processes to share the memory for the same ordinary files. When the address space in the process receives another mapping of ordinary files, the process accesses the mapped common file in the same way as a normal memory access without read/write (Zhong and Hu, 2017). In this way, the mmap method is easier than read method. Therefore, the network video surveillance system based on embedded Linux and ARM technology may adopt mmap method for video image data acquisition. The video acquisition using mmap method includes three steps. First, call the control command VIDIOCGFBUF in the ioctl function to get the parameters related to the camera and other data acquisition devices, such as frame buffer parameters. Then initialize the parameter video_m buf. The program for this step is if(ioctl(vd fd, VIDIOCGMBUF, &(vd videom buf) < 0 perror(error init VIDIOCGMBUF/n) (4) After calling the function, bind video-mbuf and mmap to get the function prototype void mmap (voidaddr, int prot, int f lags, int fd, off_toffset. Using this function prototype, mmap may correspond to the pointer in the memory mapping area on successful return, and the returned value decreases by 1 if fails. Then the application is run to read the area accordingly. After completing the above operation, video image data acquisition using mmap method will be performed using the control command VIDIOCMCAPTURE in the ioctl function. 3.5 Compression of image data Compression of image data means compressing the color image data captured by the camera into JPEG format. The basic elements of the JPEG algorithm are encoder, decoder and exchange format (Qiu et al., 2016). The acquired image data and various tables can be compressed according to the specified flow in the encoder. The decoder is able to decompress the compressed image data and the tables according to a predetermined flow so that the image data can be reconstructed. The compressed image data is exchanged for different application environment in the exchange format. The data compression process is described. First, the format of the image data to be compressed is initialized and called. After calling, initialize the compressed JPEG image quality and then perform compression. After the compression is completed, the compressed image data is copied and entered into the JPEG data variables. The memory is freed and the data variables are destroyed, returning to the initial state. 4. IMPLEMENTATION OF NETWORK VIDEO SURVEILLANCE SYSTEM BASED ON EMBEDDED LINUX AND ARM TECHNOLOGY The network video surveillance system based on embedded Linux and ARM technology is realized via network programming through the Socket interface. The Socket interface is a file descriptor and a special I/O serial port. 134

4 All Socket interfaces in the system contain the description protocol, local ports and local addresses (Wang et al., 2012). The socket shall contain description protocol, local port, remote port, local address and remote address. There is a function similar to the open file in Socket for calling. Through calling of this function, the subsequent data transmission, connection establishment and other related operations can be achieved using Socket. In general, image transmission through Ethernet using UDP is superior to Socket in view of real-time performance. However, the shortcoming is that the network cannot be connected and the function of error checking and correcting is not available. When UDP is adopted, in the event of network congestion, many packets will be lost. JPEG standard is adopted for the encoder/decoder in this system. The image data is compressed in the form of frames. During transmission of the compressed images, blurring of images will occur (Wan and Wan, 2012). To avoid problems such as image blurring after transmission and improve the correctness of image data transmission, it is necessary to implement relevant protocols in application layer in the network video surveillance system. By using the TCP/IP protocol during communication, the above problems can be solved, and the real-time transmission is good. The network transmission process of the system includes the following steps. First, a connection request from the client is listened via Socket interface. Then the connection is established. The image data is compressed according to the client's needs, and sent via TCP/IP protocol. Figure 2 shows the network transmission process of network video surveillance system based on embedded Linux and ARM Technology. Figure 2. Network Transmission Process of Network Video Surveillance System Based on Embedded Linux and ARM Technology As can be seen from Figure 2, the system creates a Socket using the web server, and then initializes it into a complete TCP socket. The Socket will bind the port, and listen to the connection request from the client. When the Socket interface receives a connection request from the client, the server will respond quickly and create a new thread, then send the video data required by the client using the TCP/IP protocol (Gu and Wang, 2012). The sent video data consists of two parts: data and frame header. The system will call the read/write programs to read the video data. The software of the system is developed on PCs. After the development of software/hardware platform is completed, the software will be transplanted to establish the system. After the system is established, the corresponding testing environment should be constructed. 5. EXPERIMENTS ON NETWORK VIDEO SURVEILLANCE SYSTEM BASED ON EMBEDDED LINUX AND ARM TECHNOLOGY 5.1 Construction of the test environment The test environment consists of two parts: the browser and the hardware platform. The hardware platform is built using the PC and the development board. FriendlyARM SBC2410 development board is adopted. The embedded Linux system and the applications related to the terminal are transplanted. Connect the USB camera, and connect the cable with the development board to construct the local network, so as to complete the construction of a hardware platform. The browser environment is built using the Firefox browser, and the Java plug-in is used so that the browser can support the Java program. 5.2 Testing the system The testing process is as follows: start the server and the USB camera. Enter the Website in the browser to authenticate the user. After verification, run the program. After authenticating the identity of the user, the program will call the JAVA program in the browser, and the video images captured by the USB camera will be transmitted to the browser window. The test results show that, the size of the monitoring window formed by the USB camera is The video image in the browser window is clear. The quality of still object images is good, and the image is not distorted. Moving objects can be displayed clearly, to achieve real-time monitoring under the visual network. 135

5 6. BRIEF CONCLUSION In summary, the network video surveillance system based on embedded Linux and ARM technology runs well, more stable compared with the traditional monitoring system, featuring excellent scalability and reliability. The main advantage of this monitoring system is low cost and simple to operate, no additional equipment. As long as the browser supports, we can provide users with clear and real-time video surveillance screen. The network video monitoring system developed in this paper is just a basic form that can realize the monitoring function of the video system. However, there are still many areas that need improvement, such as video storage, multi-path video capture, pan control and alarm functions, etc. Through the improvement and optimization of these functions, the network video surveillance system based on embedded Linux and ARM technology can be further improved and will be more stable. ACKNOWLEDGEMENTS This work was supported by a grant from the Science and Technology Plan Program of Suihua Science and Technology Bureau (SHKJ , SHKJ ). REFERENCES Cai Q. (2 014). Design of network video surveillance system based on Linux, Electronic production, (23), Du W.L., Cao J.T. (2015). Design of wireless video surveillance system based on ARM-Linux, Measurement and control technology, 34 (03), Chen L.Y., Fan D.G. (2014). The acquisition and transmission of embedded microprocessor under the environment of the video stream, The science and technology, 12 (05), Gu S., Wang J.H. (2012). 3G wireless video surveillance system based on ARM Linux, Modern electronic technology, 35 (23), Han W., Pei C.M., Wang Y.Q., Yang X.Q. (2 013). Design of wireless video surveillance system based on ARM technology, Modern electronic technology, 36 (20), Qiu X.J., Chen M.S., Huang G.J. (2016). The design and implementation of video monitoring system based on Cortex-A8 tracking, Computer and digital engineering, 44 (03), Qiao R.A., Li X.H. (2015). Design and implementation of multi-channel video surveillance system based on embedded Linux platform, Computer and digital engineering, 43 (07), Shi Q.S., Fan D.Y., Chai X., Cao P.F., Geng Y.H. (2015). The construction and analysis of embedded Linux root file system, Computer measurement and control, 23 (02), Song L.T. (2015). Research on embedded network video surveillance system based on Web technology, Information communication, (07), Wan T., Wan S.M. (2012). The design and implementation of embedded Web remote video monitoring system, Modern computer (Professional Edition), (21), Wang H.Z., Peng H. (2015). Design and implementation of embedded video surveillance system terminal software, Microcomputer and application, 34 (06), Wang L.L., Qi S., Zhu L.L. (2012). Design of smart home monitoring system based on embedded Linux, Electronic design engineering, 20 (03), Xie J.B., Wu B.N. (2 013). Research on video acquisition and transmission system based on ARM11-Linux, Microcomputer and application, 32 (08), Xu X.F., Li L.S., Yan Q.S. (2013). Application of ARM11 and Linux in network video real time monitoring system, Journal of Yunnan University of Nationalities (NATURAL SCIENCE EDITION), 22 (05), Zhong W.L., Hu W. (2017). Design of network video surveillance system based on embedded system, Research on Urban Construction Theory (Electronic Edition), (01),