Re: Issue 687 in lilypond: Enhancement: inequal MIDI quantization of equal durations (swing, rubato)

[lilypond]

Comment #25 on issue 687 by arvidgr: Enhancement: inequal MIDI quantization  
of equal durations (swing, rubato)
http://code.google.com/p/lilypond/issues/detail?id=687

I took the liberty of fixing the two TODOs commenting in swingIt (so that  
e.g. a 4. would be scaled right) and trying it on a real-world example.   
The example is in copyright, so I can't post it here, but here's a few  
observations:

It looks swingIt must be called on a beat.  If I'm on an upbeat, I have to  
compress that note manually.  No surprise really.

Also, SimultaneousMusic isn't handled well.  From what I observed, one  
voice will be swung and the other left straight.  In some (or even most)  
cases, this will make the rythm go out of whack, giving barcheck errors and  
unreadable scores.

So as it is, it can't be used on all the music of a staff if that staff  
splits up into temporary voices.  (Which is exactly what the piece of real  
music I was applying this to did all the time.)  Workaround:

\swingIt { a8 a 4. a8 a }
  << { a8*2/3 | % as I said, manually.
       \swingIt { a8 a a a % ...
     }} >>
  << { b8*2/3 | \swingIt { b8 b b b % ...
     }} >>
;; ...etc.

And with that somewhat tedious workaround, it works!

Simultaneous music (temporary voices) could probably be handled by calling  
the working part of swingIt recursively.

Cheers,

-- Arvid

Attachments:
        swing.ly  2.8 KB