Subject: Re: [linux-audio-dev] gain curves, interpolation, etc.
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Wed Nov 29 2000 - 16:34:18 EET
On Wed, Nov 29, 2000 at 01:52:28PM +0100, Jörn Nettingsmeier wrote:
> how about this:
> use a breakpoint approach, and add a feature to "curve" a segment
> between two breakpoints by automatically adding a number of new
> points in between.
>
> - mark two breakpoints
>
> - open context menu:
This sounds a bit fiddly, and you really don't want to be exposing
exponential curves to the user, it wants to look linear, but infact the
gain would be exponential. When I'm fading I think of the action I make
with a slider, which is more or less linear, but the gain curve is
exponential (or something like that).
Often you just want a short crossfade. Select a point in two tracks, hit
crossfade and it fades around it. If it sounds nasty you make the fade
a bit longer. Isn't this the stuff that ProTools makes really easy?
> i'm assuming here that linear interpolation between breakpoints is
> easy enough on the cpu to allow this to be computed real-time during
> playback without hogging too much power - i may be wrong.
1st order interpolation is cheap, but causes dicontinuities in the 1st
derivative, which are often audible. I don't know if theres a metric for
telling if a given discontinuity will be audible or not, but I think the
effect would be made worse by dynamics processing.
- Steve
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