Built-in audio controller - kAudioHardwareIllegalOperationError
Built-in audio controller - kAudioHardwareIllegalOperationError
- Subject: Built-in audio controller - kAudioHardwareIllegalOperationError
- From: Andreas Doerr <email@hidden>
- Date: Tue, 5 Mar 2002 16:32:00 +0100
Hi,
I am using the built-in audio controller on a G4 PowerBook.
The application determines the default output device and the default
input device. Since the default audio controller supports input and
output I get the same device id for both devices. So far so good.
Later the application tries to add two IO procedures through the
"AudioDeviceAddIOProc()". One for the output device and one for the
input device. Adding the output IO procedure succeeds. Adding the input,
i.e. second, IO procedure (using the same device id) fails. The error is
"kAudioHardwareIllegalOperationError".
The actual device seems to be "AppleDBDMAAudioDMAEngine". I know, that a
device is permitted not to accept more than one IO procedure and that
one IO procedure would be enough. However the code is generic and does
not distinguish between two separate devices for input/output and one
device providing both, input and output.
So my question is, could anyone please explain *why*
"AppleDBDMAAudioDMAEngine" refuses to accept a second IO procedure from
the same client? Is this the behavior for every built-in audio
controller?
Thanks,
-Andreas
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