[mythtv] Re: compiling mythtv frontend for cygwin

Doug Larrick doug at ties.org
Thu Sep 30 10:33:29 EDT 2004


Mario L wrote:
> Well if that is the case that you have some A/V sync code already
> written, then perhaps I won't be having to learn TOO much about myth's
> AV sync system.  Nonetheless, I'm taking some printouts of some of the
> myth directX code with me to class today to go through and try to make
> sense of.

Some advice here for you guys, from the guy who wrote the new video sync 
subsystem in MythTV.

The only video sync method that stands a chance of working right now is 
"usleep with busy-wait."  I have no idea how precise usleep is on 
Windows... if the answer is "good enough" you can defer writing a 
Windows-specific video sync method for now (though you'll want to do so 
in future).

If the answer is "not very" you need to write a new subclass of 
VideoSync that works on Windows... one that is synchronized to the 
vertical retrace is best, but one that just uses a timer interrupt would 
work also.  Call its TryInit method just like all the others do.

On the audio side, your audio out class just needs to provide the 
current timestamp of the audio that's playing *now* (including any 
soundcard buffering).

Other than that, the a/v sync code should be platform-independent.

-Doug
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