Video Monitoring System Based On DaVinci Technologies

Digital Video Monitoring System develops rapidly and has been widely used with the progress of multi-media technology, video compression technology and network communications technology. Video Monitoring System which takes embedded video Web server as the core has the most developable potential. Based on embedded real-time multi-tasking operating system, it has several advantages, such as wide-region distribution, easy to constitute complex monitoring network, stable performance and could be dispensed without personal management and so on. DaVinci technologies introduced by TI provide a complete set of components, including the software system and the development tools, which make it become a very efficient digital multimedia application system.This system is developed based on TMS320DM6446 DaVinci platform. DaVinci chip DM6446 is a high-performance digital multimedia SoC, which integrates ARM926EJ-S core with 300-MHz clock rate and TMS320C64x + DSP core with 600-MHz clock rate, and cleverly solved the communication and resource sharing problems lying between the dual-core. DaVinci processor contains SoC using scalable and programmable DSP, optimized accelerator, and also contains rich peripheral devices (such as digital video, digital audio, high-speed network , the high-speed DDR2 memory, ATA hard drive and a variety of storage interface cards). This highly integrated method reduces the cost of the whole system, and meets most needs of various digital video devices considering the price, performance and function.The system adopts C language to development software based on the FC8 Linux mainframe. This system achieved the Video Monitoring System, and used many software development module such as the embedded operating system MontaVista Linux, Codec Engine, DSPLink driver and other peripheral drivers, which enhanced system performance and shortened the development cycle of the system. The most critical and key innovation of DaVinci technology is that the Codec Engine (codec engine) has been introduced into this system, which is a series of the application programming interface using expressions and operations to implement xDAIS algorithm, namely VISA APIs. The use of Codec Engine framework can perfectly achieve communication and data-sharing between the two core of DaVinci. Codce Engine quotes RPC concept, treating ARM as a client and DSP as a server. The physical link is the shared DDR2 memory between the two processors, and the physical link communication protocol is DSPLink.This system realized the video monitoring system based on B/S framework. Based on Embedded Web server (EWS), the server integrated three functional modules: video capturing, video encoding and video transmission. There are three threads in the system, including EWS thread, video capturing and coding thread, and video transmission thread. Video Transmission Module realized the function of the RTSP streaming media service. It uses its own socket different from EWS to transmit video stream and web pages. For transmitting video stream, it uses RTP/RTCP/UDP protocol, and for EWS it uses HTTP/TCP protocol. The client uses browser to realize the function of monitoring through the embedded player in the Web page.Embedded Web Server (EWS) is a Web server that will be embedded into the embedded system, with the support of the corresponding hardware platform and software system, to achieve the whole or partial functions of universal Web server according to the need of application. EWS can exchange information with any client via HTTP protocol, making clients able to transparently monitor equipment status like the local machine.DaVinci platform has special video processor and video processing subsystem. TVP5146 chip is a high-quality digital video decoder chip. The concept of V4L is introduced into Video Capture driver, using ioctl function to setup and operate the equipment, and using mmap to obtain video data, complete video capture.The implement of Video encoding function is based on Codec Engine framework, by calling VISA APIs to achieve a H264 encoder. Before operating, Encoder needs two modules: dsplinkk.ko and cmemk.ko. Dsplink.ko module establishes the communication link between ARM and DSP while Cmemk.ko allocates data memory for ARM and DSP to share.Video transmission module used RTSP/RTP/RTCP. It is the core of the video monitoring system. RTSP is the controlling protocol, which is initialized from the server and transmits video and audio data stream directly. It only provided remote controlling function for data transmission is completed by RTP. RTP is a real-time data transmission protocol, which provides timestamp, sequence, and other ways to handle time matters between real-time data transmission. RTCP is the controlling part of RTP, managing service quality.In general, this paper is designed to realizes the video monitoring system based on DaVinci technology. It adopted B/S structure in the system, taking full advantages of DaVinci technology, to achieve the goal of a embedded video monitoring system.