Re: [LAD] Determining Phase

On Mon, Jun 27, 2011 at 02:35:23PM +0200, pshirkey@email-addr-hidden wrote:

> Would this result in some kind of reverb type effect as Fons suggested?

One of them would sound like a resonance, it would 'smear out' some
frequency bands. Many of them combined could be made to sound like a
reverb. Such filters are commonly used as part of reverb algorithms,
e.g. zita-rev1 has 8 of them.
 
> I'm looking for a way to adjust the phase of a signal rather than the
> amplitude. Does such a plugin already exist? If not which ladspa plugin
> would be the most suitable to start from?

Tricky. A sudden change of phase would sound as a click, and
a gradual one would be a change of frequency. This is because
phase and frequency are related:

  frequency = derivative of phase,
  phase = integral of frequency.

Are you somehow trying to match phases across a crossfade
or something similar ? There's no general solution for that.
The way apps like e.g. zita-at1 do this is to estimate the
pitch (fundamental frequency) of the signal and either skip
or jump ahead an integral number of cycles with a crossfade.
That way the phases do match. There's AFAIK no solution for
this for an arbitrary signal.

Ciao,

-- 
FA
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