[PD] Rép : looping at the end of sample

[Patrice Colet]

 Allright, it seems you are looking for a crossfade loop implementation,
that is quite usefull for looping audio in realtime, without getting clicks at loop point...

I might have something to start with, it's attached.

 This patch uses cyclone objects because it has been originaly developped by a student using maxmsp native objects.

[trapezoid~] and [pong~] for crossfading with one phasor~ signal, and [wave~] for reading the wavefile.

I'm not sure about how to set the fading time, originaly expr was designed like this:

[expr 1./pow(2. \,$f1)]


The minimum table lenght is equal to loopsize + fadetime/2. [trapezoid~] makes the amplitude ramps, and [pong~] decays the ramps for reading both loopstart, and after loopend.


I'm still looking for pd-vanilla native implementation of this patch...


Colet Patrice

----- Mail original -----
> De: "Jean-Marie Adrien" <jma at jeanmarie-adrien.net>
> À: "pd-list at iem.at List" <pd-list at iem.at>
> Envoyé: Jeudi 2 Août 2012 10:32:09
> Objet: [PD] Rép :  looping at the end of sample
> 
> Hi
> sorry, the correct word is probably sustain part, the
> post-attack-stable part of sound that you may be able to loop
> easily, for instance the quasi-steady state of a piano tone after
> the attack during the quasi-flat decay.
> Something found in archives presents very clearly the problem, and a
> possible implementation :
> 
> 
> Let's suppose this is the sample:
> |-----SS-----LB-----LE------|
> where:
> SS= sample start (where we want the sample to start playing the first
> time)
> LB= loop begin
> LE= loop end
> 
> With appropriate calculations, the two phasors can be adjusted so
> that:
> 1) Phasor A reproduces the sample the first time from SS to LE in its
> first
> cycle. In subsequent cycles it would do the same but it will be muted
> so we
> don't mind.
> 2) Phasor B reproduces the loop region; its initial phase is
> calculated in
> such a way that at the beginning, when it is muted, it will be
> producing
> garbage, but when phasor A will reach point LB for the first time,
> phasor B
> will also be on LB, so that, during ONE cycle of phasor B, the two
> phasors
> will be reproducing *exactly* the same portion LB-LE synchronously.
> 
> So, at any moment of that cycle, we can (and we must) safely switch
> from the
> output of phasor A to that of phasor B; we don't need to do a
> crossfade
> because the two outputs are perfectly identical.
> 
> So, for detecting when to switch, we can use a [threshold~] on LB on
> the
> output of phasor A, even if threshold is block quantized. No matter
> if the
> actual switching occurs with a delay of almost one block, it will
> still be
> safe to switch.
> 
> ... which seems brilliant ! (sorry i do not remember this
> contribution's author)
> Has this solution been implemented ?
> Is there an abstraction in a library addressing the same basic need ?
>  
> JM
> 
> Le 1 août 2012 à 18:54, Patrice Colet a écrit :
> 
> > hello,
> > 
> > what is 'resonance part'?
> > 
> > in principle you compute the loop size in ms and send the result to
> > [phasor~] or [vline~] for driving [tabread4~]
> > 
> > Colet Patrice
> > 
> > ----- Mail original -----
> >> De: "Jean-Marie Adrien" <jma at jeanmarie-adrien.net>
> >> À: "pd-list at iem.at List" <pd-list at iem.at>
> >> Envoyé: Mercredi 1 Août 2012 10:10:31
> >> Objet: [PD] looping at the end of sample
> >> 
> >> Hi list
> >> have looked at the archives threads concerning  managing the
> >> tabread4~'s index  for reading an audio sample from the beginning
> >> and then loop on a chunk at the end (in the resonance part).
> >> Many things during the last years, but nothing very clear to me...
> >> Any patch around for playing sample from start and loop at the end
> >> ?
> >> Jm
> >> _______________________________________________
> >> Pd-list at iem.at mailing list
> >> UNSUBSCRIBE and account-management ->
> >> http://lists.puredata.info/listinfo/pd-list
> >> 
> > 
> 
> _______________________________________________
> Pd-list at iem.at mailing list
> UNSUBSCRIBE and account-management ->
> http://lists.puredata.info/listinfo/pd-list
> 
-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: crossfadeLoop.pd
URL: <http://lists.puredata.info/pipermail/pd-list/attachments/20120802/a60ec759/attachment.asc>