The Video Synchronization Extension

The Video Synchronization Extension

The video synchronization extension, SGI_video_sync, allows an application to synchronize drawing with the vertical retrace of a monitor (in the case of an interlaced monitor, the synchronization is actually with the field rate instead). Using the video synchronization extension, an application can put itself to sleep until a counter corresponding to the number of screen refreshes reaches a desired value. The application can also query the current value of the counter.

The system maintains a video sync counter (an unsigned 32-bit integer) for each screen in a system. The counter is incremented upon each vertical retrace.

The counter runs as long as the graphics subsystem is running; it is initialized by the /usr/gfx/gfxinit command.

Note: A process can query or sleep on the counter only when a direct context is current; otherwise, an error code is returned. See the reference page for more information.

New Functions