(A) study on real time video I/O system

Abstract

A real-time video I/O system has been developed for record or display of moving images in real time. It is based on a DMA data transfer algorithm both for the input and output image. The system is composed of hardware and software parts. The hardware consists of computer interface, sync. and clock generator, A/D and D/A conversion logic, window controller and buffer controller. Because of speed and capacity limitation of the computer (VAX-11/780), original TV image is windowed and buffered before it is submitted to computer. The software consists of resources (RMO3 disk, Lexi DMA controller, etc.) control parts and data path control parts. Since this application is time-critical, VAX mainframe is dedicated to this system, i.e. the I/O program is executed without VAX/VMS operating system (in stand-alone). It can record or display images in real time over 54 seconds. Possible image size is $128\times128$ pel$^2$ per frame. This system can also be used for still picture I/O under VAX/VMS, where the maximum transfer size is $256\times256$ pel$^2$.