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: Wed, 14 Mar 2007 04:14:13 -0700
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.
Hi Brad (and anyone else who knows Audio Hardware Plugins),
My device does indeed have input streams. I claim audio stream IDs
in my plugin's Initialize function, mark them created, and when I
attempt to select my audio plugin using the Sequence Grabber, I see a
number of things firing within the plugin.
When our app does the QTSetComponentProperty call, here is the order
of what I see firing in my plug-in:
DeviceGetProperty: muid
DeviceGetProperty: uid
DeviceGetProperty: lnam
DeviceGetProperty: livn (I list my device as alive)
DeviceGetProperty: slay (this call is asking about my two input
channels, L&R, and I return an AudioBufferList for each of those
channels)
DeviceGetProperty: slay (this call asks for stream information about
output channels, for which I have zero)
DeviceGetProperty: oink
DeviceGetProperty: slay (my input channels are being queried again)
DeviceGetProperty: thru
DeviceGetProperty: stm# (I set the stream list returned to the IDs
created in my initialize function)
StreamGetProperty: sfmt (one for channel 0 of the first stream ID,
this would be the left channel of my device)
StreamGetProperty: sfmt (the second stream ID; this would be the
right channel of my device)
It's after these last StreamGetProperty calls (with the
kAudioDevicePropertyStreamFormat property id) that
QTSetComponentProperty returns the error of -10851.
In the AudioBufferList structures I am returning from the
DeviceGetProperty calls, I set mNumberBuffers to 2 channels,
mNumberChannels to 1, mDataByteSize to 512 bytes * sizeof( float ),
and mData to NULL.
Once the processing callback actually starts up, I'll have a separate
AudioBufferList to handle the data being sent over by my device.
Is there something else the sequence grabber might be looking for
after that long sanity check of the stream? does there need to be
data (or something that's not null) in the mData fields of the
AudioBufferList?
If this is getting a little too in depth or esoteric, let me know and
I can take it over to DTS.
thanks,
michael
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