Fwd: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
Fwd: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
- Subject: Fwd: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
- From: Michael Dautermann <email@hidden>
- Date: Fri, 9 Mar 2007 23:44:45 -0800
Hi folks,
I'm still trying to solve the question I was fighting with in my
AudioHardwarePlugin a few hours back.
Under DeviceGetPropertyInfo, I set the size of the
kAudioDevicePropertyDeviceUID property to CFStringRef and for
DeviceGetProperty, I'm returning my device uid properly using:
*outString = CFStringCreateWithCString(kCFAllocatorDefault,
"MyNiftyDevice:0", CFStringGetSystemEncoding());
when I try to set the Sequence Grabber in my application to pick it
up (via QTSetComponentProperty, using the same format as WhackedTV):
this fails with a kAudioUnitErr_InvalidPropertyValue.
Anyone have any ideas off the top of their head what I might be
missing?
To add a little bit of into to my original question: in the
application my audio plugin is supposed to work with, I
programatically list out the UID's of all available audio devices
before doing the failing "setPropertyWithClass" call.
I can see four attached audio devices.
The code that list out the attached audio devices prints these lines
out:
number of audio devices: 4
device name is Built-in Microphone
ModeluidString is AppleHDA:2
uidString is AppleHDAEngineInput:1
device name is Built-in Input
ModeluidString is AppleHDA:2
uidString is AppleHDAEngineInput:2
device name is Built-in Output
ModeluidString is AppleHDA:2
uidString is AppleHDAEngineOutput:0
device name is My Nifty Device
ModeluidString is NiftyDev:0
uidString is MyNiftyDevice:0
I can also see plenty of DeviceGetPropertyInfo and DeviceGetProperty
calls firing within my Audio Hardware Plugin once my device is
enumerated from the application. The last thing that fires in my
plugin before I get the -10851 error returned up in the application
is two calls to StreamGetProperty with a
kAudioDevicePropertyStreamFormat property ID (for my left and right
channels, presumably).
Even though I seem to be setting my plugin uid correctly in both my
application and in my plugin, could something else be conspiring to
cause the app's QTSetComponentProperty call to fail with a
"InvalidPropertyValue" err (e.g. some incorrect device or stream
value being sent up via the numerous StreamGetProperty or
DeviceGetProperty calls to the plugin?) Besides the UID, does
something else need to be enabled or set in the plugin for it to be
selectable as an input device for the sequence grabber?
And lastly, is there a convention to what those :0, :1 and :2's mean
at the end of those UID's?
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