Re: [musicxml2ly] wrong durations in chorded notes with time-modifications

[Marek Klein]

Hello,
2012/9/30 pls <address@hidden>

> Sibelius 7.0.0 exports wrong duration values for chorded notes in tuplets.
>  The exported value in this example (
> https://www.dropbox.com/s/vrvdabwym9tezd0/time-modification_and_chorded_notes.xml)
> is 256 instead of 170 for a quarter note in a triplet of eighths
> (<divisions>256</divisions>).  <durations>170</durations> is not an optimal
> value for a quarter note in a triplet of eighths as there is a rounding
> difference (256*2/3=170.6666...).  The same holds for an eighth note in a
> triplet of eighths (128*2/3=85.3333... instead of 86 used here).
>  musicxml2ly does not like rounding errors.  The resulting LilyPond-code
> contains wild scaling durations and a superfluous spacer rest:
> \times 2/3 { <c'' a'>4*255/256 s512*43 r8*129/128 } r4 r2 }
>
> This is bad because we have a bar check problem here!
>
> Sometimes music applications export suboptimal/false values for divisions
> and durations.
> A solution: musicxml2ly should recalculate all durations on the basis of a
> divisions value of 6720.   This figure is divisible without remainder by
> e.g. 2, 3, 4, 5, 6, 7, 8, 16, 32, 64 and therefore can provide for note
> durations up to 256th.  A quarter note (6720) in a triplet of eighths would
> have a value of 4480 (6720*2/3).  An eighth note (6720/2=3360) in a triplet
> of eighths would have a value of 2240 (3360*2/3).  (half note: 6720*2 =
> 13440.)
>

Thank you for the report. This has been added as
http://code.google.com/p/lilypond/issues/detail?id=2878

Marek
bug squad member