Default Sound Output - Lab Environment

[Lian, Tian]

Hi,

I was wondering whether it was possible to change the default sound output for a Mac Pro, for all future users (network login).

Basically we have external speakers plugged into the back of our lab machines but the default sound for any new lab user is coming out of the internal speakers.  It would be nice if the line out jack behaved the same as the front headphone jack but that is not the case.

I've used programs such as Composer and fseventer to track changes to the system when a sound output selection is made, and the only file modified is the /Library/Preferences/com.apple.audio.SystemSettings.plist.  However, there's two problems preventing me from just editing the contents of this plistt:


 1.  The plist doesn't appear to be read at login, only written when a change is made.  Making a change in the sound output reference in the plist doesn't reflect in the Sound GUI or in actual performance.
 2.  The sound output preferences in this plist are by UID's.  Which means even if I could change the default output in this plist and it were read at login, it would only apply to that particular UID and not to future lab users.

As of now, I've resorted to using Workgroup Manager to initiate a small script at first login that opens the System Preferences, selects the sound pane, and then the output pane, and then selects the Line out option.  While this is hideously obtrusive and completely visible to the logged in user, it does what we need and only recently started giving problems with the script not being able to find System Preferences.app by itself; but that's another issue and is still substantially better than plastering signs on the computers telling the user how to make the change themselves.

So I will ask, is there a more elegant way to change the default sound output of a Mac Pro for a lab environment?

Thank you,
Tian
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[Reed Laughlin]

On Tue, Sep 1, 2009 at 8:12 AM, Lian, Tian <tianlian@...> wrote:

> Hi,
>
> I was wondering whether it was possible to change the default sound output for a Mac Pro, for all future users (network login).
>
> Basically we have external speakers plugged into the back of our lab machines but the default sound for any new lab user is coming out of the internal speakers.  It would be nice if the line out jack behaved the same as the front headphone jack but that is not the case.
>
> I've used programs such as Composer and fseventer to track changes to the system when a sound output selection is made, and the only file modified is the /Library/Preferences/com.apple.audio.SystemSettings.plist.  However, there's two problems preventing me from just editing the contents of this plistt:
>
>
>  1.  The plist doesn't appear to be read at login, only written when a change is made.  Making a change in the sound output reference in the plist doesn't reflect in the Sound GUI or in actual performance.
>  2.  The sound output preferences in this plist are by UID's.  Which means even if I could change the default output in this plist and it were read at login, it would only apply to that particular UID and not to future lab users.
>
> As of now, I've resorted to using Workgroup Manager to initiate a small script at first login that opens the System Preferences, selects the sound pane, and then the output pane, and then selects the Line out option.  While this is hideously obtrusive and completely visible to the logged in user, it does what we need and only recently started giving problems with the script not being able to find System Preferences.app by itself; but that's another issue and is still substantially better than plastering signs on the computers telling the user how to make the change themselves.
>
> So I will ask, is there a more elegant way to change the default sound output of a Mac Pro for a lab environment?
>

There is a command-line tool I saw mentioned on the Mac OS X
Enterprise mailing list that looks like it would be at least a little
less user-visible.

http://code.google.com/p/switchaudio-osx/

-Reed
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