采用大规模专用OSDC芯片的数字视频混合器研究

讨论了基于大规模OSDC(0n Screen Display Control)集成电路的数字视频混合器(Video Digital Mixer)的设计原理．数字视频混合器广泛应用于高速公路、治安卡口、十字路口等交通管理领域，对于自动化和智能管理有着重要的作用．现在普遍使用的数字视频混合器存在功能单一、无法显示彩色字符、采用低速的串行通信接口、字库容量小、没有时间日期显示、字符显示和视频信号无法同步等问题．所述的数字视频混合器实现了在输入的视频信号上叠加可自定义的字符或图符，通过PC机的PCI接口实现对字符显示的位置、字符的大小、字符的颜色等的控制．内置的时间、日期控制器可以协同控制单元实现平滑、无闪烁的时间和日期显示．采用带看门狗功能中央处理期能够保证系统的高度稳定，独特的双端口总线实现了对闪存的单向写入和双向读出。对所用到的主要集成芯片的功能和特点进行了说明．将采用大规模集成电路设计的数字视频混合器和以前使用中小规模集成电路设计的数字视频混合器进行了对比。得到了非常显的技术进步．

Digital Video Based on LSI OSDC

In the article, we circumstantiate the principle of video digital mixer (called VDM below), which is based on LSI OSDC (On Screen Display Control) chip. VDM device is universally used in speedway, toll bar and crossroad. It is very important in automatic and intelligent traffic management. Nowadays the VDM being used has a lot of shortcomings such as lacking of versatile functions, being unable to display colorful characters, still using low-speed serial COM interface co communicate with computers, having little character storage space and no real-time date-time displaying function, being hard to synchronic with video signals, etc. The VDM mentioned in this article can add user-defined characters or icons on video signal through the PCI interface of computer. The user can set the position, color and size. The internal date-time controller can cooperate with the main control unit to realize smooth, blinkless date-time display on screen. We use a MCS51 compatible CPU with the watchdog funciton to see that the system will have high reliability. We elaborate a two-way date/address bus so that two devices can access flash ROM at the the same time. We compare this VDM with previous MSI architecture VDM and get the apparent advance in technique. In the article, we also describe the property of main ICs used in VDM.