[mythtv] Mac OS X video: QuickTime implementation

Nigel Pearson nigel at ind.tansu.com.au
Thu Sep 9 03:13:46 EDT 2004


I theorised:
> 	I can't quite work out why performance is so bad for you
> and Bruce. As long as I am not running the debug version,
> even the v1 display code was fast enough for my large stream.
> My machine has the latest and greatest, but I thought that
> _any_ G4 would have enough hardware acceleration to do at
> least scaling, and probably YUV2RGB, in hardware (with v2).

Bruce observed:
> Something seems really weird with all this. I tried (in the 
> NuppleVideoPlayer)
> disabling video, and the audio stutters. I tried disabling audio and 
> the
> video stutters...

	Yes, I remember similar problems before Jeremiah developed
the audioout module. I think NVP needed the timing information
from the audio module to sync the AV. I had some horrible hack
in NVP::OldAVSync(), but I can't seem to make my current setup
have the same problem when I disable audio.


>  no matter what, my CPU is maxed at 100% when its playing,
> and I get prebuffering pauses.

	I tested on my PowerBook G4 last night. Stuttering audio
after a few seconds, then video jumping as it got prebuffering
pauses. CPU at 100% all the time. I suspect that the audio
threading setup has some problems, but it could just be a load
problem (e.g. TCP/IP delays when no remaining buffers).

	I am thinking of writing an audiooutputnull.cpp that would
be invoked when the user types "none" for the audio device.
It would make it a lot easier to test these sort of problems.

--
Nigel Pearson, nigel at ind.tansu.com.au | "In this city I confess
Telstra BI&D, Sydney, Australia       |  god is mammon, more is less
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