The Software Design Of OSD Subsystem For Network Video Recorder

With the growth of demand for social security, the video surveillance system has been widely used in various fields of security. Network Video Recorder is a terminal equipment of video surveillance system, with functions such as the management of surveillance, storage, and the interaction between human-computer. The OSD system in this article is a key component of the NVR system, the research and development of high-time,low space embedded OSD system has a high value of theoretical research and engineering applications significance.This article designed and implemented the OSD system software for video surveillance system basing on RMI processor and TI DM6467 processor's hardware platform. Overall system as a whole architecture is based on modular theory, it can be divided into interactive module, GUI module, the OSD data transmission and communication module, the video decoding and GUI data superimposed module. It has completed the functions such as the OSD data processing, the communication between modules, human-computer's interaction. These modules are relatively independent to each other in function, so it achieves low coupling between modules and high scalability.Aiming at the requirements of small storage space in embedded devices, according to the system platform, Microwindows is transplanted and tailored on the RMI and TI DM6467 environment, at last file's storage space significantly is reduced. Aiming at the requirements of the OSD system in time, the using of RMI multi-core processors optimizes the parallel calculations for image data's conversion, to reduce the display delay; In the overall data processing flow, the three aspects of optimization to improve the real-time, DMA module is used to control the PCI bus transferring, then we obtain changes in the region to realize the GUI data's refresh, and finally the mouse layer is blended through DM6467's VDCE module. After three above stages are optimized, the maximum OSD display time for single-frame decreased significantly, effectively reaching the requirement of real-time refreshing every 40ms.