RE: [linux-audio-user] Acid for Linux ? - Pitch shift

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Subject: RE: [linux-audio-user] Acid for Linux ? - Pitch shift
From: Mark Knecht (
Date: Tue Dec 10 2002 - 21:12:13 EET

Just some ideas for you...

Actually, the pitch modification part is handled quite nicely here in
Linuxland by freqtweak. However, to date freqtweak is pretty static in terms
of how it manipulates frequency over time.

Acid has the ability to shift samples by known amounts, so that if I have a
bass line in C, I can shift it up a major 4th to F and it will fit into the
sound quite easily. This function in Acid works pretty well over a limited
range, say +/- a major 6th, but starts to fall apart pretty badly at an
octave, in my experience. (It depends a lot on the library.)

Until this morning I hadn't considered using freqtweak to accomplish the
same thing. Today I would have to take an input wave file for the base line,
then shift it appropriately and write it back to disk as a separate wave
file, using more disk space and creating more problems at the app level
dealing with yet another wave file to be read and played back.

Maybe a future development might be freqtweak itself, but:

1) Modified to be a ladspa plugin

2) Modified to have some built in mechanism to step the frequencies up and
down by known amounts

3) Having a way to call those frequency changes through an API

Some sort of feature set in this general space would go a long way towards
accomplishing what you can do today with pitch manipulation in Acid.

Just some ideas for you...

-----Original Message-----
[]On Behalf Of Brian
Sent: Tuesday, December 10, 2002 10:53 AM
Subject: RE: [linux-audio-user] Acid for Linux ?

Well, with ladspa one could always make a tempo edit plugin, which would
allow one to change the tempo of a sound file that's had the ladspa effect
applied. I'm not good enough at c/c++ yet to do that, but ladspa seems to
be pretty wide open in terms of the types of effects that could be
created. I would think that the functionality in Recyle could be cloned in
a ladspa plugin, that way many diverse systems could use the plugin
without having to change the UI, as the Acid functionality with "painting
in audio" is more of a convenience, the real functionality is its ability
to match tempo and pitch of disparate samples. Its really just a time
shifting effect that changes tempo without changing pitch.

On Mon, 9 Dec 2002, Mark Knecht wrote:

> Steve,
> Not only that, but better to have app developers that are passionate
> about the app they are developing. Shoving Acid-type operation into an
> existing app from the outside should never happen. Having a developer
> to pull it in is totally different.
> Mark
> -----Original Message-----
> From:
> []On Behalf Of Steve
> Harris
> Sent: Monday, December 09, 2002 1:24 PM
> To:
> Subject: Re: [linux-audio-user] Acid for Linux ?
> On Mon, Dec 09, 2002 at 12:04:18 -0800, Mark Knecht wrote:
> > IMO Acid functionality would be better placed in some other app, or
> being
> > spawned as a new app.
> Agreed, I dont like all encompassing apps, better to have samller
> targetted apps.
> - Steve

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