Beam quavers in bigger groups

[creature]

I haven't looked at the beaming logic code, but I think alphaTab groups quavers and smaller in groups of up to one beat. Consider:

:8 1.6 4.6 1.5 3.5 1.4 3.4 1.3 3.3 | :16 1.2 4.2 1.1 4.1 1.2 4.2 1.1 4.1 1.2 4.2 1.1 4.1 1.2 4.2 1.1 4.1

However, I normally see quavers written in larger groups – generally groups of four. You can tell alphaTab to render this way:

:8 1.6 4.6 {beam merge} 1.5 3.5 1.4 3.4 {beam merge} 1.3 3.3

But writing {beam merge} gets repetitive for longer passages.

I think (but am not certain!) the only rule is "beaming should not cross the midpoint of a bar". I have examples in print music of odd numbered beam groups, and beaming starting offbeat.

Here's some examples I have from various publishers, both for guitar and otherwise. Hal Leonard (drop D tuning):

Wise Publications:

Backbeat Books:

Here's a fun example from Chopin Op 9 No 1, which is in 6/4 time. This is from the urtext edition, but Schirmer engraves it identically. It shows beaming of up to half a bar, apart from the tuplet group in the right hand at the end of bar 3:

I think increasing the default group size would make alphaTab's default rendering more idiomatic and easier to read.

[Danielku15]

Beaming definitely is one of the older and less advanced features in alphaTab. I never extended much there.

After checking some references there is definitely a lot of room for improvement:

1. Custom grouping rules
2. Better automatic Stem Direction
3. Configuring Horizontal beams
4. Configuring rests under beams
5. Feathered beams

I think it makes sense to add some construct which allows configuring such options. Some rules are bar-wide, others maybe specific to a group.

We don't need to add all features directly, but we should be prepared to have a good spot for them. Most file formats are rather explicit on individual beams and the software calculates beams while writing.

For a start, having custom rules is a good step forward. I think having the info as part of the data model is the best path (not a setting). For other input formats than alphaTex developers would need to reconfigure the data model after loading.

I'll add a workitem for this soon. In the meanwhile you could try to calculate the beam groups in your own code and apply the forcejoin/forcebreak to the datamodel. The scoreLoaded event is a good spot for adding such things.

References:

https://musescore.org/en/handbook/4/beams
https://musescore.org/en/handbook/3/beams
https://mymusictheory.com/rhythm/beaming-in-groups/
https://help.flat.io/en/music-notation-software/notes-beaming/

[Danielku15]

#2399 added to track custom beaming.