IOProc never called after AudioDeviceStart
IOProc never called after AudioDeviceStart
- Subject: IOProc never called after AudioDeviceStart
- From: Mitch Jones <email@hidden>
- Date: Mon, 27 Oct 2008 10:24:23 -0700
Hi all,
I've inherited some code that makes use of basic CoreAudio routines to
setup a device and get it started to play sound. This has generally
been working fine.
However, I've got a case where the AudioDeviceIOProc passed to
AudioDeviceStart is never called. I know this because there's no
sound, no logging occurs from my callback, and as a last resort, I
tossed an abort() as the first thing in the callback, and the app
never quits.
Given the nature of the code, I can't post it verbatim, but I can
paraphrase it.
//this all happens on a secondary thread. everything returns noErr as
the result
AudioHardwareGetProperty(kAudioHardwarePropertyDefaultOutputDevice,
&theSize, &devID);
//in this case, this call fails because the requested sampleRate isn't
supported. However, disabling it doesn't change the behavior.
AudioDeviceSetProperty(devID, NULL, 0, false,
kAudioDevicePropertyNominalSampleRate, propSize, sampleRate);
AudioDeviceAddIOProc( devID, ioProc, userData );
//start and stop the device to deal with crashes we've seen on MacPros
during wake
AudioDeviceStart(devID, NULL);
AudioDeviceStop(devID, NULL);
...
//another thread then calls this
AudioDeviceStart(devID, ioProc);
At this point, I see the HAL thread running and that it appears to be
invoking the callback, at least based on its backtrace in thread
viewer, but I never see it enter the callback.
I thought it might be involved with the threads run loops as that's
something that isn't regularly run or even referenced from the threads
in question. That didn't seem to make any difference and in fact, I
created a small test app to see how CoreAudio responds when being
called from multiple threads without explicit run loop execution and
the ioproc was always called.
I've also tried the "throwing darts in the dark" approach by disabling
parts of the code, like AudioDeviceStart/Stop, without any change.
I'm seeing this problem on both a MacPro and Macbook Pro running
10.5.5. The code is compiled targeted at the 10.4 sdk.
Any thoughts on what might be going wrong here would be really
appreciated.
Thanks
--
Mitch Jones
email@hidden
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