[linux-audio-dev] Tuning

james at dis-dot-dat.net james at dis-dot-dat.net
Fri Jan 28 14:57:31 UTC 2005


Back in the days before I converted my windows partition to ext3, I
used Cubase with a number of VST instruments and effects.

I miss a number of these, but there is usually something equivalent or
something that will one day be equivalent in the Linux world.

One thing I haven't been able to replace so far is the Oberheim
OB-Tune plug-in.  This was an amazingly useful plug-in that would take
an audio input and make sure it stayed in tune.  It worked on guitars,
vocals, synths, whatever.

There were a number of ways to use it.  You could define a set of
notes that were allowed, and audio would be made to be in tune with
the closest note (useful for phrases) or you could specify a single
note.  This was all parameterised, so you could write changes to these
throughout a track.

Is there anything like this out there at the moment for Linux?

If there isn't, does anyone have any idea how it works?  I might
consider implementing something similar, but I'm not sure where to
begin.

Here's what I'm thinking:

Operate in smallish chunks.  Find the most intense frequency (FFT or
such) and decide how far that is from the desired frequency.  Scale
accordingly, preferably with as little distortion as possible, so pack
and crossfade sections.

If anyone has any thoughts, please let me know.

I'd expect to make this a plug-in rather than a standalone app, but
I've never touched LADSPA before - is it possible to send events to
change parameters?

This might be more than I can chew, but I intend to bite anyway.

James

-- 
"I'd crawl over an acre of 'Visual This++' and 'Integrated Development
That' to get to gcc, Emacs, and gdb.  Thank you."
(By Vance Petree, Virginia Power)



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