| With the comprehensive arrival of the information age, the core technology of the monitor system develops from the traditional analog system towards a new generation of digital and network-based system, the monitoring requirements have become more sophisticated, front-end integration, digital video, monitoring network, and system integration of video surveillance system is recognized as the direction of development, audio and video server technology is a cross subject collecting the audio and video codecs, network communications, streaming media processing, artificial intelligence as a whole, the subject is from Science and Technology Department of Jilin Province, the main contents of the subject is to complete the the development of high-performance audio and video server products, the products use Hi3510 multimedia processing chip provided by Hisilicon as the core processor, use embedded Linux operating system as the system architecture,which can be mixed on the four-way streaming audio and video transmission, use H.264 codec for video, G.726 codec foe voice, the overall use C / S network management model that can accept multi-user online access at the same time, through the RTSP, RTP / RTCP protocol achieve a network of multi-functional on-demand streaming media, through the TCP protocol server and client interact under network monitoring functions, and under such platform the mobile detection function is achieved, which provides solutions for the new generation of intelligent monitoring system.The task of author in the subject is the main server-side hardware and software platform design and the realization of mobile detection algorithm.Firstly study performance characteristics of the multimedia processing chip Hi3510, Hi3510 has the ARM + DSP dual-core SOC architecture, which integrate an ARM926EJ-S and associated peripherals, as well as a high-performance DSP co-processor. The ARM926EJ-S processor works as a master chip,in which a variety of user interface, application software, operating system and protocol-processing software are running. DSP system is responsible for the audio codec processes, co-processor cooperate with video codec module to complete H.261/H.263/H.264 codec.Based on the processing core Hi3510 design the overall of hardware circuit, through the tools of the Protel 99SE complete the schematic circuit design and the realization of 6 layers PCB, the circuit schematic design includes package design, electrical properties of pin settings, connections between components, network configuration label, ERC (Electrical rule checking), netlist generation and so on, then followed the device PCB package design,and build relationship between schematics components and PCB package, the next step is importing netlist into PCB design moudle, followed with the circuit boards planning, placement and routing, DRC (design rule checking), the division of ground and power, and ultimately video and audio server hardware systems come ture.On the hardware platform the embedded Linux system is built, the composition of the system are: bootloader, Linux kernel ,initialization process, the hardware drivers and the application. Bootloader is similar to the computer's BIOS to boot the system, it will drive CPU, network chips and other basic hardware devices, Linux kernel will be loaded into memory, and make the kernel initialization process control the system, generaly ARM system selected U-boot as bootloader, here use the improved version Hiboot for the hardware system; kernel is the core component of the system, its function include memory management, process management, and timer interrupt management, module management, interface file system, device drivers, inter-process communication, network management, etc.; initialization process, the hardware driver, the application are the upper parts, which depend on kernel scheduling, but have their own separate mechanism to deal with, it is the system's main components to achieve the functions, they are the root file system's main components.Linux root file system has many formats, cramfs and jffs2 are commonly used, but they all belong to the binary image file, which need to be written to the FLASH to implement, and during the development stage NFS(Network File System) is a more effective way, it is visited by the target machine by the means of a network shared file system, which is seemed as the root file system for its application to the implementation of this development environment, known as cross-compiler environment, in such an environment can be easily the conduct of drivers and applications debugging. Were carried out in the design of the TW2834, gpio, such as character device driver design, the realization of a four-way All the way to deal with a variety of video output of video processing mode and the alarm signal input and output, and drive through the RS485 PTZ pelco agreement decoder, the realization of computer-controlled PTZ camera rotation and adjustment of program design in which the user using C / S of the network model, using multi-threaded structure of modular design, each functional module, respectively, to achieve the audio and video data collection, coding, network transmission and user control functions, data queue between threads, as well as the amount mutually exclusive mechanisms of communication and synchronization. Which, through RTSP, RTP / RTCP to achieve a real-time streaming media transmission network through TCP / IP protocol and the client server network interaction, remote control in order to achieve a streaming media format NTSC and PAL under the 1D1, 4CIF video format, such as on-demand, as well as alarm input and output device, PTZ control functions such as network monitoring.In addition, the article carried out extensive research for motion detection algorithm, to consider the feasibility of the realization of projects , the difference image algorithm is studied deeply and achieved in the user program. The algorithm achievement is based on TW2834 for its support of motion detection ,the algorithm based on difference image processing method: Detect the differences of the brightness level between the current frame and reference frame, to detect moving objects in images, server-side through the network thread accept and implement the control command of client-side to detect the motion, the client can the set up motion detection region for each video channel, the motion detection alarm information output to the user interface, while the information is also saved to documents in the system for the future calls. In this paper ,the products of the project has passed the inspection, having outstanding performance, to achieve the targets, which has achieved the functions required by the four-way audio and video server, the product can be playing an important role in the new generation of network monitoring systems. |
PDF Full Text Request