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: Thu, 15 Mar 2007 17:32:57 -0700
Hi Jeff!
Thanks for taking the time to look into this and respond.
On Mar 15, 2007, at 3:59 PM, Jeff Moore wrote:
I've been reading this and so far nothing unusual seems to be
happening except I think you need to clarify how you implement
kAudioDevicePropertyStreamConfiguration. You say:
"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."
Do you mean that you are making an ABL that looks like this:
or like this:
-------------------------------
| mNumberBuffers == 2 |
-------------------------------
| mBuffers |
| mNumberChannels == 1 |
| mDataByteSize == 2048 |
| mData == NULL |
-------------------------------
| mNumberChannels == 1 |
| mDataByteSize == 2048 |
| mData == NULL |
-------------------------------
The first one is what it sounds like you are describing. This is
incorrect whereas the second one is the correct one for describing
your device with two mono streams.
The second (correct) one is what is being returned.
if you aren't already doing so, you should instrument all the entry
points of your plug-in.
The reason why is that the API boilerplate in the HAL will try to
verify the existence of a property by calling your plug-in's
ObjectHasProperty or XXXXGetPropertyInfo methods before getting or
setting it's value. It's entirely possible that the SequenceGrabber
is looking for a specific property that you aren't implementing
currently. But you wouldn't know it without instrumenting all of
the plug-in entry points.
Do you mean I should make sure all the selectors for
DeviceGetPropertyInfo and StreamGetPropertyInfo get handled?
In my debugging output, I print out all selectors that come in
through those two API's.
The only selectors that my DeviceGetPropertyInfo implementation
doesn't handle are 'pmas' and 'namr' ( I don't see these defined in
any header files under /System/Library/Frameworks, so I am not sure
what to do with them or if they matter ).
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