Re: Read-only parameters
Re: Read-only parameters
- Subject: Re: Read-only parameters
- From: Marc Poirier <email@hidden>
- Date: Wed, 27 Nov 2002 22:28:14 +0100 (CET)
>
My thinking about parameters that are readable but not writable when
>
I was designing the flags was to provide a way for an AudioUnit
>
to report back dynamically changing values relating to the internal
>
state of the DSP. Some examples would be: dynamic compression amount
>
in dB, peak signal level, average power level in dB, pitch (for a
>
pitch tracker) in hertz or absolute cents, tempo in BPM for a
>
tempo detector, etc. Thus the UI would be able to dynamically
>
display the value of these types of parameters to provide feedback
>
to the user of what the DSP is doing. This is critical for setting
>
the threshold on compressors and this sort of thing...
Oh yeah, that makes plenty of sense, I didn't think of that...
>
To me it seems like parameters which are neither readable nor writable
>
make no sense at all. Writable but not readable also seems a bit
>
suspect but a bit of creative thinking could probably come up with some
>
arcane uses for it.
Well, we have two plugins that have unreadable and unwritable parameters.
For one of the plugins (Transverb), there are two parameters that only
affect the way how the custom GUI works. So it only makes sense to
display those parameters in the custom GUI. We don't want them displayed
by a generic GUI or showing up as an automatable parameter in hosts that
display such things (like Logic). In the other plugin (Geometer), there
basically are a few parameters that select modes, and then other
"refinement" parameters that are used to modify some aspect of a
particular mode. Every mode has its own refinement parameter, so there
are a bunch of those (in the custom GUI, we hide that fact by only
displaying one slider per mode selector and then reassigning that slider's
associated parameter whenever the mode is changed). We didn't want to
have to redo the parameter layout or range for the mode selectors every
time we added new modes, so we decided to just leave space for lots of
modes, and for now hide the unused modes and associated refinement
parameters. Actually, there's really no need to do any of that in AU, but
we're also still (unfortunately) doing VST, too, which is not so smart
about a lot of things... So anyway, I guess it's more just for
cross-compatibility with VST.
But anyway, those are the two applications of unreadable and unwritable
parameters that we've done, although maybe turning off the IsReadable and
IsWritable bits is not the best way to indicate what's up with those
parameters...
On Wed, 27 Nov 2002, James McCartney wrote:
>
http://www.ganssle.com/misc/wom1.jpg
>
http://www.ganssle.com/misc/wom2.jpg
Heh heh heh... :)
Marc
_______________________________________________
coreaudio-api mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/coreaudio-api
Do not post admin requests to the list. They will be ignored.