[gmpi] Re: Topic 8: Parameters

  • From: Paul Davis <paul@xxxxxxxxxxxxxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Fri, 08 Aug 2003 00:02:25 -0400

>After all, when you automate a parameter, what are you really doing?
>You're sampling a continuous signal (knob movement), quantising it, and
>passing it to the plugin in a compressed form (discrete events).
>  Your plugin then (hopefully) interpolates and smooths the parameter to
>prevent zipper noise (reconstructing the original 'smooth' signal).

this is not always true. 

when automation curves are constructed graphically, there may never be
a continuous signal, just a set of discrete control points. sometimes,
the CP's are there to describe a continuous signal, in other cases
they just mean "at this time, change the value to this".

when they are constructed by using any kind GUI element, the
continuous signal (mouse or knob motion) gets quantised long before
the host ever sees it (e.g. mouse interrupt handling and/or polling by
the underlying GUI), and not necessarily very well quantised either :)

>Parameters are not fundamentally different from audio inputs, just a form of
>signal compression.

true, but there is a deep problem in that the compression step often
happens outside the control of the host (either in the mind/hand of
the user, or in an underlying UI), and thus the compression and
decompression steps cannot be symmetric. its very apparent that one of
the many areas in which windows/macos audio+MIDI apps show their
maturity is their ability to apply a certain level of domain knowledge
and common sense when interpolating parameter changes supplied by the
user ("give them what they want, not what they ask for").


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