WinSGL: synchronizing displays in parallel graphics using cost-effective software genlocking

摘要

This article presents a software genlocking approach for unmodified Microsoft Windows systems, requiring no specialized graphics boards but only a low-cost signal generator as additional hardware. Compared to existing solutions for other operating systems, it does not rely on any real-time extensions or kernel modifications. Its novel design can be divided into two parts: a dedicated driver reads an external synchronization signal via interrupt lines. A user-space application performs the synchronization using EnTech PowerStrip [EnTech Taiwan, PowerStrip Version 3.61, http://www.entechtaiwan.net/ util/ps.shtm] by inserting or removing lines to the invisible part of the images output by the graphics board. Robustness to potential frame losses is achieved through continuous consistent timestamping. Tests yield an accuracy of up to ±1/2 line deviation from the external signal and a low CPU load of 2% on current PC systems. Our system has been designed to be compatible with off-the-shelf graphics hardware and digital output devices based on LCD or DLP technology. Our solution can be employed to build cost-effective VR installations such as large tiled displays and spatially immersive environments using commodity PC clusters. Furthermore, displays synchronized to camera acquisitions allow for novel and convenient systems in the area of 3D scanning and smart adaptive displays, two application areas we will present in the second part of this article.