[mythtv] Audio sync problem with recent CVS build

[Tom Hughes]

In message <200504102308.42117.ijr at case.edu>
        Isaac Richards <ijr at case.edu> wrote:

> On Sunday 10 April 2005 12:14 pm, Tom Hughes wrote:
>> In message <200504101142.50829.ijr at case.edu>
>>
>>           Isaac Richards <ijr at case.edu> wrote:
>> > On Sunday 10 April 2005 10:39 am, Tom Hughes wrote:
>> > > I've attached the frontend log output in case it helps - the only
>> > > thing in there that I noticed that is new is the use of OpenGL vsync
>> > > support. Previous ATrpms builds have not had that and so RTC timing
>> > > has been used.
>> >
>> > There's a reason that that defaults to off.
>>
>> Are you saying that it's know not to work on some systems?
>
> Yes, that's why it defaults to off.

I've done some investigating now and it seems that despite
glXQueryExtensionsString indicating that GLX_SGI_video_sync is
supported any call to glXGetVideoSyncSGI or glXWaitVideoSyncSGI
will fail.

Unfortunately by that time myth is already committed to using
OpenGL sync and it just logs the error and carries on as if the
call had worked.

Probably the thing to do is to try calling glXGetVideoSyncSGI in
OpenGLVideoSync::TryInit and return false if it fails, that way it
would fall back to RTC instead.

It is of course an interesting question as to why those calls are
failing on some systems...

Tom

-- 
Tom Hughes (tom at compton.nu)
http://www.compton.nu/