David Nahman ([EMAIL PROTECTED]): > I'm writing a program that needs to synchronize with the vertical > refresh of the screen in order to trigger an external piece of > hardware. Is there a way through Xlib to detect when a vertical > refresh has happened? Or is this something that is video card driver > pecific?
This is currently video card specific. With nVidia cards and the binary drivers, you can use poll() on /dev/nvidia[0-x] to have your process block until the next refresh. With mga, radeon, r128, i830, (what else?) drivers, using the new DRM for X4.3, there is a DRM ioctl you can use to get information about the refresh rate. Look for drmWaitVBlank and associated code in libGL for how to use the ioctl. Other then that, there are a bunch of card-specific codes around providing refresh interrupts as kernel modules. In new versions of svgalib, they include a kernel module to provide this functionality through their API, although it's unclear if it is 'safe' for use along with X. As well, the mplayer program includes some kernel module drivers for overlay surfaces which includes some refresh sync code, but it's not really used by them currently to my knowledge. I'm working on some sort of library to abstract the nvidia binary drivers and the new DRM method, and maybe other methods if they are clean. If anyone else is interested in helping out with this, let me know. Hope that helps, -Billy -- Billy Biggs [EMAIL PROTECTED] _______________________________________________ XFree86 mailing list [EMAIL PROTECTED] http://XFree86.Org/mailman/listinfo/xfree86
