Re: Patch to autobeaming code.

[Trevor Daniels]

Carl D. Sorensen wrote Tuesday, August 19, 2008 7:42 PM

> What did you intend to have happen when beatLength is changed?  AFAICS,
> \time 12/16 sets measureLength to (ly:make-moment 12 16) and beatLength to
> (ly:make-moment 1 16).  When a user sets beatLength to (ly:make-moment 1 
> 8) it
> says to me they want to have an 8 in the denominator of the time 
> signature,
> even though they want the printed value to be 16.
>
> For me, that should be the only reason for using beatLength.  I don't 
> think
> beatLength is the appropriate thing to use for changing beaming.  That's 
> what
> beatGrouping is for.
>
> If it were up to me, I would not allow users to directly change 
> beatLength.  I
> don't think that a disconnect between the \time setting and the beatLength
> setting should be allowed.  If users want to fake time signatures, they 
> can --
> and the techniques to do this are shown in the manual.
>
> But, as long as we are allowing users to set beatLength to  1/8, when the
> measure length is 12/16, aren't we really saying that the measure should 
> be
> 6/8 (i.e. 12 16th notes = 6 eighth notes, and the measure should be 
> divided
> into beats by eighth notes)?
>
> What other interpretation is there for beatLength?

The beatLength value controls the sub-beating within compound
signatures when manual beaming is being used with
subdivided beams.  Try these:

\relative c'' {
 \time 12/8
 \set subdivideBeams = ##t
 %default - 12 sub-beats based on 1/8 notes
 a16[ a a a a a a a a a a a a a a a a a a a a a a a]

 % 3 sub-beats based on 1/2 durations
 \set Score.beatLength = #(ly:make-moment 1 2)
 a16[ a a a a a a a a a a a a a a a a a a a a a a a]

 % 4 sub-beats based on 3/8 durations
 \set Score.beatLength = #(ly:make-moment 3 8)
 a16[ a a a a a a a a a a a a a a a a a a a a a a a]

 % 6 sub-beats based on 1/4 durations
 \set Score.beatLength = #(ly:make-moment 1 4)
 a16[ a a a a a a a a a a a a a a a a a a a a a a a]
}

Is there an easier or better way of doing this?

Trevor