Re: Beam subdivision

[Trevor Daniels]

tisimst wrote Tuesday, March 10, 2015 4:52 PM

> The other question the OP was asking is can 
> the group default to have TWO full beams 
> across the group, ...
> I had a look through the IR and couldn't find 
> anything that says it will only use a SINGLE 
> beam across the whole group. 

The snippet in NR 1.2.4 Beams which shows how to subdivide beams says:

"When set, multiple beams will be subdivided at intervals defined by the 
current value of baseMoment by reducing the multiple beams to just one beam 
between the sub-groups."

But you're right in the sense that there is no accessible property that 
controls the number of inter-group beams, and there should be, or even better, 
LilyPond should just do the correct subdivision if subdivideBeams is set.  In 
"Behind Bars", on pages 156-157, Elaine Gould makes it quite explicit that 
using a single beam to separate groups of four 64th notes is wrong.  She says, 
"the number of beams separating the groups [should be] equal to the duration of 
the groups they separate".  A group of four 64th notes equals a 16th, so two 
such groups should be separated by a 16th beam, i.e. two beams.  Four such 
groups should have two beams between first and second and between third and 
fourth groups, and a single beam between second and third.  She gives an 
example showing exactly this.

There is an enhancement request for this: see
https://code.google.com/p/lilypond/issues/detail?id=2361

Trevor