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Re: Garageband 3/audio units odd behaviour
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Re: Garageband 3/audio units odd behaviour


  • Subject: Re: Garageband 3/audio units odd behaviour
  • From: Rick Sustek <email@hidden>
  • Date: Thu, 8 Feb 2007 15:13:46 -0800

Oh I certainly feel your pain, Dave, with regards to supporting multiple plugin formats, and trying to keep the code as clean and common as possible!

It seems like this thread has leapt into the philosophical realm, regarding the basic question of if the audio processing threads should be left running, when there really isn't any work to be done. There seems to be good pros/cons for both approaches, and some of them depend on the live vs. non-live contexts, and the specific purposes of certain host apps.

No easy answer, and no clear industry consensus... sighhhh!

I try to keep the basic perspective that it really isn't my CPU to waste, it belongs to the user, and the user most likely wants to run more than just my lowly software. The vast majority of the users would not be happy to see their CPU running at 100%, but neither hear nor see any activity. So along these lines, in applications where it makes sense, I like seeing a button that allows the user to stop/ start the whole audio processing machine.

However, in Dave's case (and others) there is a desire to "get some audio thread time", under the control of the plugin, rather than via the host. Or, at least a standard way to tell the hosting app to "give me some thread, man!".


Have fun, -Rick








Begin forwarded message:

From: "Muon Software Ltd - Dave" <email@hidden>
Date: February 8, 2007 2:27:32 AM PST
To: <email@hidden>
Subject: RE: Garageband 3/audio units odd behaviour
Reply-To: email@hidden

Well, not so much an assumption, but more of a defined role.
The defined role of the plugin, is to hook into an audio stream and
do something useful with it. The fact that a plugin can
exhibit a GUI
at all, is really just fluff, to make it easier to modify the
parameters of the processing.


I can take that onboard for an AU effect. But for an AU instrument or
generator I think there should be something in the spec that takes into
account the fact that audio could be generated without MIDI having been sent
to the instrument first by the host.



It is certainly arguable that your feature of providing
"browsing and
previewing" is outside the established role of what an audio plugin
should do, but let's not! ;-)


No, lets not go there....but I am tempted to add that it wasn't a problem in
Peak when I set up two of your machines on the Bias booth at NAMM to
demonstrate this particular AU for Jason, so at least Peak appears to share
a similar world view to me :-)



So to get your feature, there is nothing stopping you from launching
a new thread, and opening your own instance of the chosen audio
output device, and playing out some sound. With a few tricks, you
could even run the sound through the processing code of your plugin,
so that the preview would be modified accordingly. What you
would not
be able to do, is to also hear the effect of any plugins that were
down stream from yours, since their processing is associated to the
host's thread, not yours.


There's nothing to stop me, no you are absolutely correct. I could easily
access the audio device myself and stream my previews to it.


However, many developers don't have the luxury of coding for one specific
host or even platform. In fact I would say that the vast majority of us
operating at a commercial level have to make the same code work well as VST,
AU, RTAS etc. To have to implement such a heavyweight hack just to get the
AU to work properly in GB3 is a direction I wouldn't want to take the code
in.



BTW, you mention AU Lab as a host that doesn't exhibit the problem.
But, if you click on the little waving icon, you can stop the audio
processing thread, and indeed see the same problem there!


Of course, and you can do the same thing in Sonar on windows IIRC. You do
have to worry though about what the benefit of stopping the audio thread to
the user actually is however...


Kind regards
Dave

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 >RE: Garageband 3/audio units odd behaviour (From: "Muon Software Ltd - Dave" <email@hidden>)

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