Re: AUAudioFilePlayer offline rendering
Re: AUAudioFilePlayer offline rendering
- Subject: Re: AUAudioFilePlayer offline rendering
- From: William Stewart <email@hidden>
- Date: Mon, 9 Jul 2007 12:10:37 -0700
On 09/07/2007, at 10:33 AM, patrick machielse wrote:
Hi,
I'm trying to use AUAudioFilePlayer and I'm running into problems.
The context: I'm processing audio files in an offline setting. I
set up
a small AUGraph, consisting of an AUAudioFilePlayer, followed by a
variable number of custom units, ending in a generic output unit. I
process the autdio files by calling AudioUnitRender on the output in a
loop. The basics work; I get processed audio out.
The problem: AUAudioFilePlayer seems to revert to producing zeroed out
data at random (I've installed a render callback on the file player to
verify this). Once this happens, the output usually remains at zero
level for
the duration of the file. I've not been able to determine a pattern in
when it will start producing zeroes, or at which offset in a file. I
only know that it seems to happen more often when I'm doing less
processing in the graph; if I'm just pulling in data as fast as I can
getting zeroed data from the file player is almost guaranteed.
What I've tried:
- setting the kAudioUnitProperty_OfflineRender property. It's not
supported by AUAudioFilePlayer it seems (but I believe this doesn't
mean
that the file player can't be used at all in an offline context).
Currently, that is the case (and this is the cause of the problem).
As you are in an offline context, you could use the ExtendedAudioFile
API directly (so instead of connecting the AUFilePlayer, you could
use a callback and in the callback use the ExtAudioFileRead call - it
should work fairly easily I think).
Bill
- setting the kAudioUnitProperty_MaximumFramesPerSlice to a safe
value. This doesn't
help.
- AUAudioFilePlayer defines two properties for adjusting its internal
buffers, but these are not implemented.
Has anyone had any success with AUAudioFilePlayer in an offline
context? Am I overlooking something (warning signs maybe??).
patrick
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