[mythtv] [PATCH] Mac OS X audio patch

Nigel Pearson nigel at ind.tansu.com.au
Mon Aug 30 19:49:28 EDT 2004

> After your video patch appeared, I was afraid you'd beat me to
> the punch and have it all working before I finished this version.

	Sadly, work got in the way :-(

> BTW, I did at least key the Core Audio driver to a new config flag,
> rather than CONFIG_DARWIN, so it would be easier to accommodate Darwin 
> users

	I was thinking that we don't need another USING_ define,
and it should be automatic, something like:

#ifdef Q_WS_MACX
     return new AudioOutputCA(...)
#elif defined ( CONFIG_DARWIN )
     return new AudioOutputDarwin(...)

but then I wondered if Mac OS X users might like to choose
between the heavyweight CoreAudio/AudioUnits version
(whose native type of float = redundant conversion?),
and a possibly simpler HAL version which only supports
a few sample rates, via your define.

	At the moment, my HAL test code has tried opening
IOAudioEngines, IOAudioDevices, IOAudioStreams and
IOAudioPorts. None of them seem to support the CF properties
that are documented in IOKit/audio/IOAudioDefines.h
Very frustrating. I am wondering if the API that layers
like CoreAudio use is actually private.

> I'm sure there are awful AV sync bugs lurking -- on my 450 MHz test 
> machine, the video looks like a webcam, so I can't really test it too 
> well. ;)  I set "disablevideo" to true in NuppelVideoPlayer.cpp, and 
> get sound with an occasional drop.  Can you try this test too, as an 
> additional data point?

	I did extensive testing last night (My 1.3G G4 doesn't need
the video disabled). Audio playback has been perfect, with video
catching up after high-bandwidth sections, but only if that avsync
"clipped negative delay" output is not filling up a Terminal window.

	I will try today with some smaller video streams
(i.e.  Nuppel conv. analogue instead of DVD-quality DVB)
and see if it is a CPU load thing, or something else.

Nigel Pearson, nigel at ind.tansu.com.au | "Gentlemen,
Telstra BI&D, Sydney, Australia       |  you can't fight in here
Office: 8255 4222    Fax:  8255 3153  |  - this is the war room!"
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