[PD] midi syncro

Miller Puckette mpuckett at man104-1.ucsd.edu
Mon May 14 00:17:25 CEST 2001


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...


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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