Re: Audio Reflector
Re: Audio Reflector
- Subject: Re: Audio Reflector
- From: Jeff Moore <email@hidden>
- Date: Fri, 9 Feb 2007 14:16:10 -0800
On Feb 9, 2007, at 12:17 PM, Nick Nallick wrote:
I'm new to CoreAudio and am trying to get my feet wet with the
AudioReflector example. Unfortunately I've run into some problems
and I'm hoping somebody can point me in the right direction.
I originally built the AudioReflector driver on a PPC machine but
wasn't able to get it to work. It never showed up in the audio
device list. When I took the same project to an Intel machine it
seemed to work better. This isn't really important to me but I
thought it might be worth noting.
I build and run that code on both PPC and Intel systems. If it's not
showing up in the device list, chances are there was something about
the way it was built that is preventing it from loading. What does
kextload -t say when you try to load it?
Note that there are some caveats to building audio drivers on Tiger.
Basically, it boils down to the fact that the headers for IOAudio on
PPC systems don't match the version of IOAudio that's in the recent
Tiger updates. What you need to do is replace those headers with the
ones from an Intel system, or just build the driver for PPC on the
Intel system.
Now that I have the driver installed I'm trying to verify that it
works. If anybody can suggest a better way to do this I'm happy to
try it, but here's what I've tried so far.
First I commented out the call to setDeviceCanBeDefault in ARDevice
to get the driver to appear in the system preference sound panel.
This works fine. Next I modified the RecordAudioToFile sample to
use the AudioReflector as input. I also had to add a floating
point format to the plist in AudioReflector to get the two to
match. My thinking was that I could then set the sound output in
the system preferences to AudioReflector and use RecordAudioToFile
to record any audio output. I've tried this with audio played from
the Finder's info window preview section and iTunes but I just get a
blank file.
My second test was via the system preferences sound panel. If I set
the output to "Internal Speakers" and the input to "Internal
microphone" and play something, the microphone will pick up the
sound coming out of the speakers and I'll see an indication on the
input panel's "Input Level" meter (if I turn up the sensitivity
somewhat). My thinking was that if I set both the input and output
to AudioReflector I could also see what I'm playing through the
output register on the input level meter. Unfortunately there's
nothing there.
Can anybody tell me what I'm doing wrong, or if there's a better way
to test this? Perhaps I'm just completely misunderstanding how the
reflector is suppose to work.
I usually test the driver by having HALLab or AULab or whatever play a
file with the reflector as the output. I usually record the input of
the reflector using the Input Window in HALLab.
--
Jeff Moore
Core Audio
Apple
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