Re: Proper API for selecting devices
Re: Proper API for selecting devices
- Subject: Re: Proper API for selecting devices
- From: Jeff Moore <email@hidden>
- Date: Thu, 18 Nov 2004 12:26:04 -0800
The HAL provides the list of available devices through the
kAudioHardwarePropertyDevices property. Then for each device, you can
query the kAudioDevicePropertyDataSource family of properties to access
the input source (e.g. line in or internal mic on my PB).
The Audacity guy is right when he says that the model on Mac OS X is
different than it is on Windows (probably Linux too, but I don't really
know) where the input sources for the hardware are treated in a flat
fashion. Mac OS X presents a more hierarchic model where the source is
accessed through the hardware it is attached to.
On Nov 17, 2004, at 7:53 PM, Randy Wilson wrote:
I've been trying to use the open source "Audacity" app to record on my
Mac (both G5 dual 1GHz and 600MHz G3 iBook), but it inserts all sorts
of clicks and noise when it records, even though the freeware "Audio
In" application records just fine.
Audacity has a drop-down list of devices to use for input, but under
OS X this list doesn't do anything. You have to go into preferences
to choose the device, and even then you don't have the option to
select the "mic in" or "line in" mode like you can from Apple's System
Preferences.
I e-mailed the Audacity list, and I got the response below. The
response made me think that perhaps there would be someone on this
list that would know the proper way to get a list of inputs for the
various devices that are available for audio in. Then the Audacity
guys could add that into the code and select devices properly.
Let me know if you have suggestions, and/or send them to:
email@hidden.
Thanks!
There is an odd confusuion in the way OS X does audio I/O. Whilst you
can select between different audio input devices (sound cards, USB
etc) there is no functional API for programs to change which input is
used on a given device (CD, line, mic on a single card). This is set
from a drop-down list on the toolbar when audacity is run on other
OSes.
But even if we have to choose the device in the Preference menu, it
appears that Audacity doesn't currently get a full list of what is
available, and thus may be trying to grab from the wrong source.
I'm guessing you should be setting the device to the Onkyo in the
audacity preferences, and then you will get the line or mic input,
dependant on the setting in Mac OS. Not very elegant, but as I say,
the interface is not consistent with other OSes (where the device and
source choices are independant).
Richard Ash
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--
Jeff Moore
Core Audio
Apple
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