should the mBox change my understanding of the CoreAudio API?
should the mBox change my understanding of the CoreAudio API?
- Subject: should the mBox change my understanding of the CoreAudio API?
- From: Christopher Penrose <email@hidden>
- Date: Tue, 2 Sep 2003 19:05:57 -0400
More than a year ago I coded some CoreAudio based software for
accessing various CoreAudio interfaces. My code works reliably with
Apple's built-in hardware, the emagic emi 2|6, and the Delta 1010. I
don't have a Hammerfall interface, but the software I have written
reportedly has problems with it.
I have an mBox here, running with digidesign's 1.2 CoreAudio driver,
and I was pretty astonished to learn that my otherwise reliable
software could cause MacOS X to freeze. I encountered a message in 4
languages politely asking me to power off my computer. Of course it
was the only option save for ctrl-cmd-power.
After this failure with the mBox, I decided to use a program that I had
coded to poll audio devices to discern a problem. It is my
understanding that a CoreAudio hardware device is configured with a
particular audiostream whose nature can be revealed with the audio
device's associated AudioStreamBasicDescription. Is this correct?
Well, when I poll the mbox, the currently selected hardware, with the
following code:
/* Get the basic device description */
propertySize = sizeof(outputStreamBasicDescription);
status = AudioDeviceGetProperty(outputDeviceID, 0, 0,
kAudioDevicePropertyStreamFormat,
&propertySize,&outputStreamBasicDescription);
and print out the description, the value of mChannelsPerFrame I receive
seems incorrect. My program reveals "1", while mBytesPerFrame seems
correct with a value of "4". Is the digidesign driver bugged or is my
understanding incorrect here? Should I give up until digidesign fixes
the hypothetical bug or do I have something to learn about polling the
description of the currently configured stream?
Thanks for any help....
Christopher
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