[PD] Non-transposing delay

Andy Farnell padawan12 at obiwannabe.co.uk
Fri Jun 6 17:07:26 CEST 2008


Yes, that's a great point. IIRC that is mainly for slow moving
envelope/control signals. I wonder, if you did it with audio
then you'd have a limited number of times to apply it in a given
interval because the worst case means you get an accumulating
DC offset that will go out of bounds. (?)




On Fri, 06 Jun 2008 16:58:32 +0200
Roman Haefeli <reduzierer at yahoo.de> wrote:

> On Thu, 2008-06-05 at 22:36 +0100, Andy Farnell wrote:
> > 
> > And conversely, a delay buffer with a ordinary movable read point
> > (which is what I guess  you really want in this case) will always
> > cause a click since there's no reason why jumps between arbitrary 
> > samples will be smooth. Of course there will be no trasposition
> > since the read location changes instead of the rate.
> > 
> > Transposition may be desirable, but clicks rarely are. As it
> > stands you can either have smoothness with transposition, or 
> > no transposition and clicks.
> 
> iirc, there is a technique described in millers book, which i don't
> recall the name of, which is used to avoid discontinuities, when jumping
> from one to another time point in an audio stream. this is achieved by
> adding a ramp to the signal, that smoothes out the difference between
> the samples at the jump. i used this technique to create clickless loops
> with arbitrary length. i assume, it would also work for a
> non-continuous, but clickfree changeable delay (without transposition). 
> 
> however, if jamie wants it to be continuous, then probably the technique
> as shown in 3.audio.examples/I07.phase.vocoder.pd could be used, which
> is very cpu-time consuming, though.
> 
> roman
> 
> 
> 
> 
> 		
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