Re: subdivideBeams broken?

[Hans Aberg]

On 21 Jun 2009, at 20:16, Carl D. Sorensen wrote:

> I think you misunderstand how beatGrouping works.
>
> In previous versions of LilyPond (2.10, and less than 2.11.x, where  
> I don't
> remember what x is -- it was about August 2008), beatGrouping didn't  
> work
> for autoBeaming.

It is rather that LilyPond has changed a couple of times in the past,  
so the code I have compiled differently, and therefore I gave up on it  
for a while.

> beatGrouping sets the points at which autobeams end, unless there are
> explicitly set rules.
>
> beatLength sets the points at which beams are automatically  
> subdivided.
>
> By default, beatLength is the numerator of the time signature.
>
> By default, beatGrouping is set according to the time signature for  
> standard
> time signatures (you can see the defaults in scm/music-functions.scm).
>
> In your case, LilyPond was doing exactly what you asked it to.
> subdivideBeams set to ##f, the beams were not subdivided.  And the
> beatGrouping of (2 2 2 1) was overridden by your explicit rule to  
> break
> beams at 4/16.
>
> With subdivideBeams set to ##f, beams were broken at 4/16 (according  
> to your
> rule), and subdivided every 1/16 note, since that's the beatLength  
> you had
> by default.
>
> If you want beams to be subdivided at (2 2 2 1), then just set  
> beatLength to
> 1/8, and you'll get what you want.

Yes, beatLength will do a (2+2)+(2+1) beaming. Though this is one  
possible beaming for what I am writing now, my problem is that I have  
bunch of different meters. For example, I may want (2+2)+3,  
(2+2)+3+(2+2) and so on.

I have looked at the stuff you describe above ("Sub-dividing beams",  
page 60/70 in the manual). It seems that beatLength assumes that  
subdivisions should happen on multiples of this time values. This does  
not work with a meter beaming like 3+(2+2) or (2+1)+(2+2). See code  
below - it seems that this 3 causes problems.

The auto-beaming model is perhaps too crude for subbeaming all these  
meters - in some, a trick might do.

  Hans


----
\version "2.13.1"

\score {
\new Staff <<
  \relative {
    \time 7/16
    \set beatGrouping = #'(2 1 2 2)
%    \set beatGrouping = #'(3 4)
    \set subdivideBeams = ##t
%    \set beatLength = #(ly:make-moment 1 8)
    f8 f16  f f16 f f | f16 f8  f8 f16 f | f16 f16 f16  f16 f f8 |
    #(override-auto-beam-setting '(end * * 7 16) 3 16)
    f8 f16  f f16 f f | f16 f8  f8 f16 f | f16 f16 f16  f16 f f8 |
  }
>>
}
----