[PD] midi syncro

HENRY Damien damien_henry at libertysurf.fr
Wed May 16 00:10:52 CEST 2001


Hi Miller.

You where right : using the -nosound flag increase the stability of MIDI
timing : it run perfectly now even with a *very* high load of the midi
output.
I understand only now that the calculate audio checkbox is diferent than
the -nosound flag.

For info : I've use the same patch on Win98 and Linux and the MIDI timming
is better with Linux when the -nosound flag is *not* activated. when it is
activated they are both good.

I will use 2 PD in the same time one with -nosound and one other
with -nomidi. It will solve my problem.

many thanks.

dh.

De : Miller Puckette <mpuckett at man104-1.ucsd.edu> Envoyé : lundi 14 mai 2001
00:17
Objet : Re: [PD] midi syncro


> Hmm,
>
> I don't know the answers to any of this, except that, for the second
> question, notein just asks the OS to get the MIDI out as fast as possible.
> I'm surprised setting a small audiobuffer doesn't help.  Another
possibility
> is turning audio input or output (or both) off.  MIDI is timed off audio
> transfers, so if teh OS is using a large block size for audio, MITI timing
> should suffer.
>
> I'm going to work on this and see if I can improve it at all; I can
probably
> get the timing jitter down to 5msec or so but it'll never be real pro
> quality until someone figures out how to use kernel-level time tagging on
> MIDI output...
>
> cheers
> Miller
>
> On Sun, May 13, 2001 at 10:12:58PM +0200, HENRY Damien wrote:
> > Hi Miller, Hi list.
> >
> > When I send many midi event with noteon spaced like this :
> >
> > !        !        !        !        !        !        !        !
!
> > !
> >
> > I get something like this :
> >
> > !            !    !            !    !            !    !            !
!
> > !
> >
> > it's not a ramdom jiter, it's like an interference phenomena.
> > Like if the regular rythme was modulated by an other.
> > I've tried to generate an audio sound based on the same rythme, and this
one
> > is very regular : the jiter apear only on the midi output.
> > I've play with -audiobuf without any good results... With 5ms, the midi
> > rythme is 2 time slower than with 500ms or without using the -audiobuf
flag.
> > (I don't understand why)
> >
> > 1) If too many event arrive in the same time to a noteon object, does PD
> > "decide" to schedule some for later ?
> >
> > 2 )Are MAXBUFFER and DEFBUFFER in the s_nt.c code file linked to midi
> > timming ?
> > Do you think that playing with this king of buffer can solve my problem
?
> >
> > Thanks for your answer and help.
> >
> > dh.
> >




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