Re: beat length and beaming problem

[Xavier Scheuer]

On 10 October 2011 01:18, Paul Malcolm <address@hidden> wrote:
>
> I have the following (perhaps trivial) but interesting problem.
> I would like to manually set the beat length (for beaming purposes) inside
> a
> \times n/m {} construction.
> The music is 2/4 time and I need groupings of two sextuplets on the 1/4 note
> beat.
> Ordinarily
>
>
> \times 4/6 {c16 c c c c c}
>
>
> But I would like the beaming to group this sextuplet as a collection of
> three groups of two,
> not one group of 6.

Do you want to *beam* them with a 2 2 2 structure or do you want to
*subdivide* them, i.e. with an "overall beam" (the "8th note beam") and
then have a subdivision 2 2 2 for the "16th note beams"?

The first one is quite easy, by defining a "beamExceptions" rule for
24th notes (i.e. 16th sextuplet) in 2/4 times :

%%%% Snippet

\version "2.14.2"

\score {
  <<
    \new Staff {
      \overrideTimeSignatureSettings
        #'(2 . 4)  % timeSignatureFraction
        #'(1 . 4)  % baseMomentFraction
        #'(1 1)    % beatStructure
        % beamExceptions
        #'(                         ;start of alist
           (end .                   ;entry for end of beams
            (                       ;start of alist of end points
             ((1 . 24) . (2 2 2 2 2 2))   ;rule for 1/24 beams, i.e.
sextuplet 1/16
            )))                     %close all entries
      \time 2/4
      \relative c' {
        \repeat unfold 2 \times 4/6 { c16 c c c c c }
      }
    }
  >>
}

%%%% End of snippet

The latter is more difficult to define as automatic beam behavior and
AFAIK impossible for now, since it is not possible (yet!) to define
rules for subdivide beams.


> I have tried using the beatLength variable but Ive either misunderstood how
> it works or
> am doing something quite wrong.
> This is what I tried,
>
>
> \autoBeamOff
> \set subdivideBeams = ##t
> \set beatLenegth = #(ly:make-moment 2 16)
> \times 4/6 {c16 c c c c c}
>
>
> Perhaps manually setting the beatLength inside a \times n/m
> needs special consideration ?

beatLength has been replaced by in the new >= 2.14 beaming engine.
Please use baseMoment (and beatStructure).
See in the doc version 2.14 NR 1.2.4 Beams > Setting automatic beam
behavior
http://lilypond.org/doc/v2.14/Documentation/notation/beams.html#setting-automatic-beam-behavior

Cheers,
Xavier

-- 
Xavier Scheuer <address@hidden>