Re: [ARSCLIST] Dynamic pitch correction programs (was: wire recorders)

[Don Cox <doncox@xxxxxxxxxxxxxx>]

On 21/07/04, David Lewis wrote:

> Though STATIC pitch changing or time compression and expansion have
> long been a basic part of most digital editing programs I have not
> seen or heard of good DYNAMIC pitch or time correction.
>
> However, numerous plug-ins are available for correction of pitch for
> vocalists or other instrumentals which might offer some possibility of
> dynamic pitch correction. Antares Auto-tune was one of the first
> widely avaialbe and inexpensive plugs, which I understand is now
> available as a stand-alone component.

I think the problem in a disc that was recorded at varying rotation
speeds is one of time correction, not pitch correction.

This is important because the algorithms for stretching and compressing
time are much simpler than those for changing pitch, and more likely to
give good results. Time stretching is resampling, while pitch change
(without time change) involves frequency analysis and remapping.

To correct an off-centre disc, one would need a time-stretch routine
with the amount of stretch varying according to a sine wave law. The
intensity, phase and frequency of the sine wave would have to be
adjustable in real time so that the correction could be set by ear.

A very good ear would be needed.

Regards
--
Don Cox
doncox@xxxxxxxxxxxxxx