[LAD] sliders/fans

Nick Copeland nickycopeland at hotmail.com
Thu Nov 24 21:03:47 UTC 2011

> From: fons at linuxaudio.org
> To: linux-audio-dev at lists.linuxaudio.org
> Subject: Re: [LAD] sliders/fans
> On Thu, Nov 24, 2011 at 02:21:25PM -0500, David Robillard wrote:
> Suppose the minimum value of the widget would correspond to say
> -100 dB if not handled specially. If you just have a single fader
> per channel, you could arrange for the model or the DSP code to
> translate that to 'off'. That is no longer the case if you have
> 'VCA' faders.
> There are two thing you'd expect from such a system: 
> * If either the channel or the group fader is at minimum, then
> the channel must be off (zero gain).
> * If the channel fader is at -50 dB, and the group at -60 dB
> you don't want zero gain, but -110 dB. Becaus either fader is
> still in a position where you'd expect that moving it makes a
> difference.

Wow. Isn't this a far bigger topic?

For example, having a user interface definition that says UpArrow
means the controller moves up is separate from saying:

a. UpArrow and gain implies dB values
b. UpArros and Frequency control implies lin/log/exp Hz values

If we want to impose semantics on the controllers that are under motion 
then that is going to be one _big_ specification. Again, perhaps I need to
look at the HID definition we are referring too, I was actually anticipating
just the syntax of what the diverse key/mouse combinations cause rather
than what they effect.

There are some interfaces that expect fixed pixel steps for their controls,
the interfaces are not 'resizable'. Others are. I think it might be difficult 
to impose semantic meaning of any given chance in the interface guide
for that and probably a few other reasons.


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