WinSGL: Software Genlocking for Cost-Effective Display Synchronization under Microsoft Windows

Abstract

This paper presents the first 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: First, an external synchronization signal is transmitted over interrupt lines to a dedicated driver. Second, a user-space application performs the synchronization by inserting or removing lines to the invisible part of the image. Robustness to potential frame losses is achieved through continuous consistent timestamping. Tests yield an accuracy of up to ± ½ 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 and spatially immersive displays using commodity PC clusters.