Re: dynamic parameter lists
Re: dynamic parameter lists
- Subject: Re: dynamic parameter lists
- From: Ian Kemmish <email@hidden>
- Date: Tue, 4 May 2010 20:19:27 +0100
On 4 May 2010, at 14:23, Paul Davis <email@hidden> wrote:
can an AU have a dynamic parameter list? it appears to me that it
could
publish an event notifying of a change in the value of
kAudioUnitProperty_ParameterList,
and that the host should/could then get the value of that property,
and
re-inquire about the current parameters. is that legal? Are there
any hosts
that would pay attention to this?
That's what my synthesiser does - it's modular, and lets the user
create his own list of performance parameters which is potentially
going to be different for each voice.
The good news is that this doesn't (appear to) break anything. The
bad news is that it places some significant demands on the host, which
probably won't be met. Garageband, for example, will dutifully
interrogate the AU to get the new list of parameter names, and then
throw it all away and continue displaying the old ones.
To be fair, you can see why. Unless a host was written from the
ground up with this possibility in mind, it's going to create lots of
headaches on both the UI and sequencing fronts.
So I'd say:
1) if your parameters are going to be seen by the user exclusively via
your AU's own UI, then go ahead.
2) if you expect your parameters to be twiddled by the host's UI or by
automation, then it's probably better not to do this if you can avoid
it.
A workaround I use, is to allow the user to also bind parameters to
MIDI controllers within my AU's UI. Then, the user sees the nice
names for the parameters within my UI, but can still twiddle a bunch
of anonymous MIDI controllers within the host.
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- - -
Ian Kemmish 18 Durham Close, Biggleswade, Beds
SG18 8HZ
email@hidden Tel: +44 1767 601361 Mob: +44 7952
854387
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