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, 2 Dec 2004 12:23:58 -0800
The data source controls, like all controls, can be manipulated
regardless of whether the device is performing IO or not. Try it
yourself in AMS or HALLab to see.
Without seeing a backtrace of your crash, it's hard to say what would
be causing it exactly. But if I had to guess, I'd say that it's
happening because DataSourceControlIsSettable() is throwing an
exception that you aren't catching. The reason an exception would get
thrown is because the device probably doesn't have a data source
selector control at the address you are querying. You should always
check for the existence of the control using HasDataSourceControl().
On Dec 2, 2004, at 6:22 AM, Rolf Nilsson wrote:
Hi,
Some more questions about kAudioDevicePropertyDataSource:
> From: Jeff Moore <email@hidden>
> Subject: Re: Proper API for selecting devices
>
> Here's what I wrote the last time. It still answers the question.
>
> > 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).
Should this be done before one is actually starting using the device?
CAAudioHardwareDevice theDevice(theInputDeviceID);
if (theDevice.DataSourceControlIsSettable(kAudioDeviceSectionInput))
theDevice.SetCurrentDataSourceByID(kAudioDeviceSectionInput,
theInputDataSourceID);
i.e. before the SetupAUHAL() etc as in the ComplexThru example?
I've tried both and it seems to work on a PowerBook for selecting
between the Mic and Line-in
but the same thing crashes when a user tries it with a Digidesign
ProTools interface.
Is there anything special with Digidesign or am I doing it wrong?
I've uploaded a modified version of the ComplexThru example here:
http://www.ronimusic.com/download/CmplxPlayThru.sit
In the original example there are popup menus for selecting the device,
I've just added a couple of popup menus for selecting the data source
as well a combined menu for the
available devices/sources.
It contains the test application and also the source code as an XCode
project (it should build right out of the box )
Thankful for any comments what might be wrong?
Rolf Nilsson
> >
> > 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.
>
> I should also point out that CD audio is not accessed through an
audio
> device on Mac OS X. It is accessed through the file system, so you'll
> never find that source.
>
> The HALLab sample code (/Developer/Examples/CoreAudio/HAL/HALLab) has
> code that illustrates how to access the data source properties on a
> device. If you are having problems with the control, please post a
more
> directed question about it and I'll be happy to help you out.
>
> On Nov 19, 2004, at 5:54 AM, Rolf Nilsson wrote:
>
> >
> > Hi,
> >
> > I have exactly the same problem with my application.
> > I have recently added a drop down list for selecting in and output
> > devices.
> > Essential the same code as in the ComplexPlayThru example which
works
> > fine on my dual G4 running OS X10.2.8 or 10.3.6
> >
> > On computers that have a built in microphone only this device is
> > found, not the physical line-input. At least this is what users
> > reports.
> >
> > So how should we detect all devices?
> >
> > A workaround is to add an item in the drop down selection list that
> > just select the "default device" as set up in the system
preferences
> > sound panel
> > (same as wavemapper/midimapper under Windows)
> >
> > Rolf NIlsson
> >
> >
> > >
> > > 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
> > >
> > >
> >
> > _______________________________________________
> > Do not post admin requests to the list. They will be ignored.
> > Coreaudio-api mailing list (email@hidden)
> > Help/Unsubscribe/Update your Subscription:
> >
> >
> > This email sent to email@hidden
> >
>
> --
>
> Jeff Moore
> Core Audio
> Apple
>
>
>
>
> ------------------------------
>
> _______________________________________________
> Coreaudio-api mailing list
> email@hidden
> http://lists.apple.com/mailman/listinfo/coreaudio-api
>
> End of Coreaudio-api Digest, Vol 1, Issue 80
> ********************************************
--
Jeff Moore
Core Audio
Apple
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Coreaudio-api mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden