Re: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
Re: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
- Subject: Re: what would cause QTSetComponentProperty to fail with a kAudioUnitErr_InvalidPropertyValue err?
- From: Michael Dautermann <email@hidden>
- Date: Mon, 12 Mar 2007 19:17:02 -0700
Brad! **THANKS** very much for responding to my message.
On Mar 12, 2007, at 4:54 PM, Brad Ford wrote:
When I try to set the Sequence Grabber in my application to pick
it up (via QTSetComponentProperty, using the same format as
WhackedTV):
err = [self setPropertyWithClass:
kQTPropertyClass_SGAudioRecordDevice id:
kQTSGAudioPropertyID_DeviceUID size: sizeof(uid) address: &uid];
this fails with a kAudioUnitErr_InvalidPropertyValue.
Does your device have input streams? Setting the above property
will fail if the device is not capable of capturing audio. The
Sequence Grabber determines this by querying it for its streams on
the input side.
Yes. My device does have input streams.
I declare this by returning values in DeviceGetProperty (for the
kAudioDevicePropertyStreamConfiguration, kAudioDevicePropertyStreams,
kAudioDevicePropertyStreamFormatSupported, and the
kAudioDevicePropertyIOProcStreamUsage selectors). I also return data
for pretty much every possible selector under StreamGetProperty
(kAudioStreamPropertyDirection, kAudioStreamPropertyStartingChannel,
kAudioStreamPropertyTerminalType, kAudioDevicePropertyStreamFormat,
kAudioDevicePropertyStreamFormats,
kAudioStreamPropertyPhysicalFormat,
kAudioStreamPropertyPhysicalFormats, etc.)
The last selector I listed under DeviceGetProperty,
kAudioDevicePropertyIOProcStreamUsage, isn't fully coded out yet.
I set mNumberStreams = 2 (for left and right channels) in the
AudioHardwareIOProcStreamUsage structure being returned, but haven't
put anything into mStreamIsOn yet. Could these undefined values be
the issue?
Is the Sequence Grabber that robust in checking structures out?
thanks again,
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