VRetrace Sync

[Jim Gettys]

In fact, this, with a lot more was tried, and worked fine, at the time
we designed Sync (over 10 years ago).  We implemented and tested all
this stuff when Sync was designed.

Besides vertical retrace as a Sync counter, the intent is to also hook
up the sample clocks of any audio hardware as well; this then allows for
dead on audio/video synchronization.

So please do the tiny amount of code to hook this up....
			Regards,
				- Jim


So please, please, do the hook up.

> 
> On Saturday 18 February 2006 05:23, James Wright wrote:
> >    I hope this is the correct mailing list to post this question to,
> if not
> > please advise where it should go!
> >
> >    Does anyone know if/when X11 will be extended to allow 2d drawing
> to be
> > syncronised to the monitors vertical refresh. I already draw to a
> > backbuffer first and use XShmPutImage() to copy to the window, so
> > flickering is not a problem, but still get tearing/shearing which is
> > especially noticable when scrolling large areas.  I understand that
> this
> > also requires the event to be exposed in the kernel, but I thought i
> had
> > read that had been done...?
> 
> The kernel notification basically already exists for drivers using the
> DRM.  
> Exposing this to client applications is a Small Matter of hooking the 
> vertical retrace up to a counter in the Sync extension.
> 
> Note that as we move towards using compositing managers everywhere,
> the 
> question for all the other apps besides the compmgr is not "how do I
> get my 
> bits on the screen during the retrace" but "how do I notify the
> compmgr that 
> my front buffer contains a complete frame".  The Sync extension
> appears to be 
> flexible enough to handle this, but no one has tried it yet.
> 
> - ajax
>