Re: Piano duets on facing pages - something new in 2.8.x?

[David Rogers]

* Urs Liska <address@hidden> [2010-08-02 10:46]:

> Am 30.07.2010 11:57, schrieb Werner LEMBERG:
> > > > Is it possible to synchronize page breaks on facing pages of piano
> > > > duet music with primo on the right-hand side and secondo on the
> > > > left-hand side?


...


> It might seem obvious, but of course the two scores must contain 
> compatible music.
> Does this mean that both sides must have the same amount of music?
> While this is conceptually self-evident it is easy to write input 
> files that don't comply to it.
>
> So, how would we expect LilyPond to deal with this situation?
>
>   * Should it just try to make the best of the input and spit out
>     errors if it doesn't work out?

I can imagine a duet where one of the players "falls asleep" and the
other continues playing for a while. I guess in such a case it would be
possible either to have the first player's part stop, or just fill it up
with rests...

>   * Or should LilyPond make checks before trying to typeset the music?
>   * Should there be the possibility to manually insert checks of some
>     kind, similar to bar checks and barnumber checks?
>     What could they be like?

I don't regularly typeset music without bar lines, but doesn't Lilypond
already have facilities for synchronizing two players' parts in one
score? Probably those can be re-used - as much as possible anyway.

I think in the majority of cases having the two parts follow each
other's bar checks, and give an error when that fails, should be
sufficient.

Would some new kind of "sync point" be needed, or does Lilypond
already have such a thing for use in \cadenza sections and so on?

>   * In classical four hand music, both players have the same amount of
>     bars in the same \time
>     But of course this is no requirement for four hand music. Any
>     constellation of polyrhythmic, -metric, -timing music that can be
>     produced with LilyPond can be also used in four hand music.
>   * So I think LilyPond should just try to find synchronous possible
>     page breaking points and don't care about things like barnumbers etc.

At least in those cases where the music is sufficiently simple and/or
regular, corresponding pages should have the same number of lines, and
corresponding lines the same number of bars. These requirements should
only be broken when they will make the score bad for some other reason.
(And then they should be followed anyway IMO.)


--
Thanks
David