Re: Confused by Piano Dynamics

[Mats Bengtsson]

> 
> I'm trying to parse the piano-dynamics example (for the 1.4 series,
> posted last month).  I'm confused by this section:
> 
> dynamics = \notes {
>   \outputproperty #(make-type-checker 'dynamic-interface)
>     #'extra-offset = #'(0 . 2.5)
>   s2\fff\> s4 
>   \outputproperty #(make-type-checker 'dynamic-interface)
>     #'extra-offset = #'(0 . 2.5)
>   \!s\pp
> }
> 
> Specifically, what are the skips (s's) doing in this context?  Taking
> out the first s2 causes a syntax error.  Making it into s16 doesn't
> affect the place of the \fff, but seems to make the descrendo shorter.
> Changing the second s to an s2 seems to make everything a little
> shorter.  I'm sure this is something obvious, but I just don't quite
> get it.

Normally, dynamic indications (both absolute dynamics and 
(de)crescendi) are tied to notes. I'm sure you understand
fairly well how LilyPond will place the dynamics of the 
following line:
c2 \fff \> d4 \! e \pp

In the example file, the dynamics are typeset in a separate
context which shouldn't include any note heads. Therefore, 
the skips are use as invisible note heads, still the horizontal
placement is the same as in my example above.

The same trick is described in the section on Dynamics
in the reference manual as a way to place several marks
below the same note.

The example file could be simplified by removing the 
\outputproperty specifications before each new dynamic
and instead add the following two lines in the definition
of the Dynamics translator:

      DynamicText \override #'extra-offset = #'(0 . 2.5)
      Hairpin \override #'extra-offset = #'(0 . 2.5)


   /Mats