Re: User-land CoreAudio driver and Leopard
Re: User-land CoreAudio driver and Leopard
- Subject: Re: User-land CoreAudio driver and Leopard
- From: Brian Willoughby <email@hidden>
- Date: Thu, 8 Nov 2007 03:50:28 -0800
On Nov 8, 2007, at 02:04, Stéphane Letz wrote:
> Can you explain a little more what this "coreaudiod" deamon is
about?
I would guess that coreaudiod is a daemon that owns all of the audio
processes, particularly the ones that execute the drivers running the
audio hardware. Because all applications share the audio hardware
and are mixed together, there must be another process to own the
final stage where all applications are mixed together. My deduction
is that this daemon process was formerly run by the user who logs in
at the console. If correct, this might explain why iTunes audio
stops when switching users, although that did not happen in some OS
versions before Tiger. Now, with Leopard, I assume that the daemon
is actually started before anyone logs in, and thus is owned by a
system user, not a mere administrator or regular user.
Thus, if any part of your driver executed operations which are
affected by user permissions, then those operations might now fail
because the permissions have shifted to a different user.
Sorry to spend all this space hypothesizing, but if I'm right, then I
think CoreAudio has just seen a great improvement. There are some
significant application classes which would be well served by being
able to run at boot time, before anyone logs in. These are usually
fixed installations that are permanently wired to some kind of
hardware, and need to be fault-tolerant enough to operate correctly
even when nobody logs in. Further, it would be great to have audio
tasks which would be able to function properly and continuously even
if someone logs out.
Brian Willoughby
Sound Consulting
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