Re: Logic and AU instruments with side-chain
Re: Logic and AU instruments with side-chain
- Subject: Re: Logic and AU instruments with side-chain
- From: Stefan Gretscher <email@hidden>
- Date: Tue, 23 Sep 2008 17:23:14 +0200
Hi Floris,
Am 17.09.2008 um 10:35 schrieb Floris Klinkert - FabFilter Software
Instruments:
At the moment, we are trying to create a stereo AU instrument plug-
in with a side-chain, but we are kind of puzzled on how to specify
the input/output configuration of our plug-in. After some testing,
we have learned the following:
1) A plug-in -only- displays a side-chain input dropdown list in its
plug-in window if it offers more than one input bus (regardless of
it being an effect plug-in or an instrument plug-in).
2) For effect plug-ins, Logic feeds the side-chain signal to the
second/last of the two input busses, as expected. For instrument
plug-ins, Logic feeds the side-chain signal to the first input bus
and doesn't use the second one at all...
Is this expected behaviour in Logic?
No. For effect plug-ins Logic uses the first input bus as main input
and the second (if present) as sidechain. For instruments the first
bus is used as sidechain if present.
For music effects it'll depend on whether you're inserting it into an
instrument or into an effect slot, it follows the logic described
above depending on the slot.
You can check which bus Logic wants to use by analyzing for which
bus(es) Logic sets an input callback. I just tested this in the
debugger with another instrument AU and it seems to work like
described - any other behaviour would be a bug, which I beg you to
file ASAP via bugreporter.apple.com
Before reporting though, please check that you're not being tricked by
Logic's AU property caching - the I/O capabilities are cached by Logic
to speed up launching the app, and this cache will only be updated
when the version number of the AU changes, or when you amnually
trigger a rescan of the AU in the AU manager. If the cache and your
actual behaviour run out of sync, odd behaviour is to be expected.
Best,
Stefan
We've also did some testing in other hosts. Digital Performer 6 also
only shows a side-chain menu when we declare two inputs, but doesn't
route audio to any of them. AULab actually does what you would
expect most: if you declare two input busses... you can route audio
to two input busses.
Since hosts react in such a different way to an instrument with a
(side-chain) input, we're not sure what is the best way to implement
this.
Has anyone tried making a AU instrument with side-chain before? Any
hints?
Thanks!
Floris Klinkert
------------------------------------
Stefan Gretscher
plug-in development & 3rd party developer support
phone: (+49)-4101-495-586 (Central European Time)
AU developer support: email@hidden
TDM developer support: email@hidden
Apple GmbH
Geschäftsführung: Georges Guyon de Chemilly
Sitz der Gesellschaft: München
Amtsgericht München, HRB 66158
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