[PD] Advice on how to handle latency in linux with Pd, jack and ardour

[Simon Iten]

thanks for the clarification. i'll ask about the latency correction for
jack-clients in the ardour forum. lately there have been some jack
plugins around (linuxdsp) so there would be a need for this there as
well.


On Tue, 2009-12-22 at 11:41 -0800, Justin Glenn Smith wrote:
> Jack cannot automatically know that PD is reading from jack and then sending back to re-record. Because of how jack is designed, there is an inevitable and predictable delay there - determined by jack, not by pd.
> 
> This has been brought up, ardour already automatically compensates for ladspa plugin latency when it has the proper information, so the infrastructure is theoretically there (ideally they could add a "one jack period worth of latency correction" toggle to the UI for each track).
> 
> Simon Iten wrote:
> > afaik all the latency introduced by jack is automatically corrected by
> > ardour. so the latency you observe when rerecording in ardour comes from
> > puredata only. there's not much you can do about this, except optimizing
> > your patch. i'm not aware of any manual latency correction in ardour,
> > but maybe i'm wrong, you should ask this on the ardour forum. you could
> > start your sourceaudio with a short and loud click sound, that way it's
> > easier to align later...
> > 
> > regards,
> > 
> > simon
> > 
> > On Thu, 2009-12-03 at 11:50 +0100, Lorenzo wrote:
> >> I've been lately messing around with a fairly straight forward
> >> configuration sending audio from ardour to Pd's adc~ (through jack)
> >> and back to ardour via MIDI (for controlling automations) or audio
> >> (trivially re-recording Pd's dac~ output).
> >>
> >> In the case of MIDI latency seems no perceptible problem.
> >>
> >> In the case of audio, where the audio is of course 'processed' in the
> >> Pd patch and eventually 'goes back' to ardour, there is latency. 
> >> This of course is expected for the nature itself of jack, what I'd
> >> like to know at this stage is not how to remove latency but the best
> >> way(s) to handle it (possibly even through raising the latency itself,
> >> as for the moment I'm not doing real-time), for example if there were
> >> some way to compensate it automatically (or at least in some 'smart'
> >> way).
> >> At the moment the best solution is to manually re-align the slightly
> >> delayed audio.
> >>
> >> Any input welcome.
> >>
> >> Kind regards,
> >> Lorenzo.
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> > 
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