Re: Microtonal midi output

[Jean Abou Samra]

Le 09/05/2021 à 19:31, Lukas-Fabian Moser a écrit :
> Hi Jean,
>
> > It is a well-known trick… See
> > https://gitlab.com/lilypond/lilypond/-/issues/3139
> Ah yes, thank you, I didn't know that. But I'm also relieved that DK 
> seems to share my misgivings about the conceptual jumble involved... :-)

Well yes. I'm not particularly happy about
it, just that I couldn't find anything simpler,
and the function would have been somewhat unuseful
without support for non-integers ;-)


> > > As Graham pointed out, LilyPond's habit of setting pitch bends 
> > > before a note and re-setting it immediately after a note whose 
> > > alteration is not in 1/2 * Z leads to strange effects with the 
> > > release (or reverb) of a note. This can be observed in examples 
> > > involving rests between re-tuned notes. I patched my LilyPond for 
> > > this: Now it never explicitly resets MIDI pitch bends, instead each 
> > > and every note gets a pitch-bend command. (Which would be crazy for 
> > > most applications, but is fine for my special needs involving lots 
> > > of re-tuned notes.) I didn't have time to find out how to make this 
> > > user-configurable.
> >
> > An option would be to go create an issue at
> > https://gitlab.com/lilypond/lilypond/-/issues
> > and attach your patch there, noting that it
> > is a work-in-progress and configurability should
> > be added. That way, someone might pick it up.
> > > - I'm already looking forward to Graham's solution to this problem 
> > > (post-processing the MIDI files using MTS messages.
> > I haven't tried it (understanding of MIDI is above
> > my pay grade), but it shoud certainly yield better
> > results.
>
> I looked into it a bit today, and I can gladly report that (while the 
> code still needs some cleaning up), I managed to patch my LilyPond to 
> automatically generate the MTS messages that Graham's Python script 
> adds in post-processing. (Of course, that wouldn't have been possible 
> without being able to use Graham's code as a cheat sheet!)
>
> As an example I attach the midi files generated by
>
> \score {
>   {
>     <c' e'>4 r
>     <$(ly:make-pitch 0 0 -1/4) e'> r
>     <c' e'> r
>     <$(ly:make-pitch 0 0 1/4) e'> r
>     <$(ly:make-pitch 0 0 1/8) e'> r
>     <c' e'> r
>   }
>   \layout {}
>   \midi {}
> }
>
> with official 2.22.0 and with my patched master. Compare with special 
> focus on the pitch of the e (which should be the same for all three 
> chords), and on what happens during release.
>
> I'm a bit nervous about my lack of insight in possible side-effects of 
> my tempering with the C++ code, but I'll try to make available a patch 
> that more knowledgeable people can at least take as a starting point.

This looks very nice! I look forward to
seeing the patch.

Cheers,
Jean