Re: User-land CoreAudio driver and Leopard
Re: User-land CoreAudio driver and Leopard
- Subject: Re: User-land CoreAudio driver and Leopard
- From: Stéphane Letz <email@hidden>
- Date: Thu, 8 Nov 2007 11:04:52 +0100
On Nov 7, 2007, at 3:36 AM, Stéphane Letz wrote:
Our user-land CoreAudio driver does not completely work on Leopard:
- it can not be seen as "default input/output" driver for
applications like iTunes or QuickTime player that use default input/
output devices. What has change under Leopard that could explain
this new behaviour?
The most likely change is that your plug-in is failing to work
properly when loaded by coreaudiod. Prior to Leopard, your plug-in
would not be loaded by coreaudiod, so you probably never had to cope
with running in a daemon outside of any user login session. This
usually leads to problems where the plug-in can't communicate with
it's daemon because of the bootstrap session differences.
Can you explain a little more what this "coreaudiod" deamon is about?
- we still implement the kAudioHardwarePlugInInterface2ID version of
the AudioHardwarePlugIn.h header, but the header has now a
kAudioHardwarePlugInInterface4ID version whith much more functions.
Can we stay with the kAudioHardwarePlugInInterface2ID version?
While your version 2 plug-in should continue to work just fine modulo
getting it to work in coreaudiod, I strongly advise moving to version
4 for two reasons. First, you really ought to support the full API
natively (v3 and v4 added several new calls). Second, only v4 plug-ins
will be loaded into 64 bit processes.
To help you out, we have included a full HAL plug-in SDK in Leopard.
You can find it in /Developer/Examples/HAL/SampleHardwarePlugIn.
- some function like AudioHardwareDevicePropertyChanged,
AudioHardwareStreamsDied... are now deprecated. What has to be used
instead?
They are deprecated in favor of AudioObjectCreate,
AudioObjectsPublishedAndDied and AudioObjectPropertiesChanged. Note
that you can see these calls in action in the plug-in SDK.
Thanks! This finally should allows us to develop a cleaner and more
compatible driver. This is really nice, even if we have now a bit of
work to use the SDK.
Will a driver developed with the SDK still load under Tiger or is it a
Leopard only thing?
I compiled the SampleHardwarePlugIn, put it in /Library/Audio/Plug-Ins/
HAL/. The driver is correctly seen by HALLab and AMS, but it seems it
can not be used as the default input/output device (in AMS). What has
to be done for that?
Thanks
Stephane Letz _______________________________________________
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