2018-08-05 13:26 GMT+02:00 James Lowe <address@hidden>:
Hello,
On 05/08/18 08:38, James Lowe wrote:
Harm,
On 03/08/18 16:03, Thomas Morley wrote:
2018-08-03 16:51 GMT+02:00 James Lowe <address@hidden>:
Hello
On 03/08/18 13:32, Thomas Morley wrote:
Hi,
while playing with the Measure_grouping_engraver
see:
http://lilypond.1069038.n5.nabble.com/changing-symbols-used-by-Measure-grouping-engraver-td215283.html
I noticed two things which may qualify as bugs.
(1) A documentation issue
I tried to get MeasureGrouping in default 4/4-time, but nothing
happened.
One has to set beatStructure and baseMoment accordingly. The current
docs make it sound it should work out of the box, though.
\version "2.19.82"
\new Staff \with { \consists "Measure_grouping_engraver" }
{
%% to get MeasureGrouping, next two lines need to be
uncommented
%\set Timing.beatStructure = 4,4
%\set Score.baseMoment = #(ly:make-moment 1/8)
\repeat unfold 8 a'8
}
Is this just a documentation issue though?
*should* it work out of the box (to use your phrase) and so
documentation is
correct and the bug is in the code?
We don't document bugs after all.
James
Hi James,
this is not a bug in the code, afaik.
But the functionality of MeasureGrouping relies on appropriate
settings for beatStructure and baseMoment.
This should be documented, that's all.
I don't know how this cannot be a bug in the code or perhaps I don't
understand how this should work but giving an example for 4/4 with the one
example doesn't help anyone either.
For instance in an attempt to edit the existing snippet, I played about with
different \time settings to see if I could show the differences - it's
always good to show a negative before showing a positive I find.
Why would using using \time values of 6/8, 5/8, 4/8 engrave something
(triangles) and 3/8 not?
Playing about with the form
\score {
{
\time X/Y
\repeat unfold 16 a'4
}
\layout {
\context {
\Staff
\consists "Measure_grouping_engraver"
}
}
}
Where X and Y change I cannot figure out why I get some engraving with some
values and not other
I've attached a screenshot of some random output values.
Why do I get something for 4/8 and not 7/8 is it because of the value of the
note and how we define a group? I cannot work out the logic to it.
So explaining it for 4/4 makes no sense in that there has to be something
more fundamental in the explanation or it is a bug.
Can you or anyone help?
James
Hi James,
If I understand correctly:
In general the time-signature says about a measure:
how many beats are present and how long are those beats.
P.e. in 3/8 there are 3 beats, each a 8th note long
In LilyPond we add a structure (`beatStructure`) to those beats (`baseMoment`),
reflecting the most common accents and determine the auto-beaming.
p.e. 9/8 is structered as three groups of three 8th-notes.
For beamings not according to `beatStructure` we set `beamExceptions`,
p.e. for 3/8
Now, MeasureGrouping may annotate groups of beats, _if_ groups are defined by
`beatStructure`, see 9/8. Single beats will not cause any MeasureGrouping,
see 3/8.
Here some test-code:
displaySomeContextPoperties =
\context Timing
\applyContext
#(lambda (ctx)
(newline)
(format #t
"timeSignatureFraction: ~a\n\tbeatStructure: ~a\n\tbaseMoment: ~a
\tbeamExceptions: ~a\n"
(ly:context-property ctx 'timeSignatureFraction)
(ly:context-property ctx 'beatStructure)
(ly:context-property ctx 'baseMoment)
(ly:context-property ctx 'beamExceptions)))
\new Staff \with { \consists "Measure_grouping_engraver" }
{
\time 3/8 \displaySomeContextPoperties \repeat unfold 3 { a'8 }
\time 4/8 \displaySomeContextPoperties \repeat unfold 4 { a'8 }
\time 5/8 \displaySomeContextPoperties \repeat unfold 5 { a'8 }
\time 6/8 \displaySomeContextPoperties \repeat unfold 6 { a'8 }
\time 7/8 \displaySomeContextPoperties \repeat unfold 7 { a'8 }
\time 8/8 \displaySomeContextPoperties \repeat unfold 8 { a'8 }
\time 9/8 \displaySomeContextPoperties \repeat unfold 9 { a'8 }
\time 1/4 \displaySomeContextPoperties \repeat unfold 2 { a'8 }
\time 2/4 \displaySomeContextPoperties \repeat unfold 4 { a'8 }
\time 3/4 \displaySomeContextPoperties \repeat unfold 6 { a'8 }
\time 4/4 \displaySomeContextPoperties \repeat unfold 8 { a'8 }
}
Terminal-output:
timeSignatureFraction: (3 . 8)
beatStructure: (1 1 1)
baseMoment: #<Mom 1/8>
beamExceptions: ((end (1/8 3)))
timeSignatureFraction: (4 . 8)
beatStructure: (2 2)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (5 . 8)
beatStructure: (3 2)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (6 . 8)
beatStructure: (3 3)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (7 . 8)
beatStructure: (1 1 1 1 1 1 1)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (8 . 8)
beatStructure: (3 3 2)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (9 . 8)
beatStructure: (3 3 3)
baseMoment: #<Mom 1/8>
beamExceptions: ()
timeSignatureFraction: (1 . 4)
beatStructure: (1)
baseMoment: #<Mom 1/4>
beamExceptions: ()
[
timeSignatureFraction: (2 . 4)
beatStructure: (1 1)
baseMoment: #<Mom 1/4>
beamExceptions: ()
timeSignatureFraction: (3 . 4)
beatStructure: (1 1 1)
baseMoment: #<Mom 1/4>
beamExceptions: ((end (1/8 6) (1/12 3 3 3)))
timeSignatureFraction: (4 . 4)
beatStructure: (1 1 1 1)
baseMoment: #<Mom 1/4>
beamExceptions: ((end (1/8 4 4) (1/12 3 3 3 3)))
So, MeasureGrouping does not happen for time-signatures where the
`beatStructure` is a list of single beats, like 3/8 or 7/8 or 3/4 etc.
At least not per default. One can try playing with `beatStructure` and probably
`baseMoment` to get MeasureGrouping, though.
See:
\new Staff \with { \consists "Measure_grouping_engraver" }
{
\time 3/8
a'8 8 8
\set Timing.beatStructure = #'(3)
8 8 8
}
Changing `beatStructure` and probably `baseMoment` ofcourse affects
auto-beaming.
We explain this already elsewhere, but probably we'll should mention
it in the section for
MeasureGrouping as well.
HTH,
Harm
Screenshot1_070818.png