duration using variable

I don't know if the following code is well written (suggestions are pretty welcome!!) but it works as I like (:)) and let me generate two different output according the tag midiOut or screenOut.

\version "2.19.40"

mynote = c

mynoteExp = {\mynote}
mynoteDouble = {<\mynote' \mynote>}

cC = {\tag #'midiOut \mynoteDouble
\tag #'screenOut \mynoteExp }

music =
{
\time 3/4 \clef bass
\cC
}

\score
{
\keepWithTag #'screenOut \music
\layout {}
}

\score
{
\keepWithTag #'midiOut \music
\layout {}
\midi {}
}

In the attached capture.png you can see the two different output, the first when using screenOut and the second using midiOut.

* * *

Now I would like to be able to increase the lenght of the musical _expression_ contained in the cC variable.

In the previous example the cC variable contains a quarter note (and a quarter bichord) and I would like to change it to an half note. I tried with the "changePitch.ly" snippet (http://gillesth.free.fr/Lilypond/changePitch/changePitchDoc-sources/changePitch-doc.pdf) writing

\changePitch {a2} \cC

but this does not work.

Here it is the whole code (I highlighted the differences compared to the previous example)

\version "2.19.40"
\include "changePitch.ly"

mynote = c

mynoteExp = {\mynote}
mynoteDouble = {<\mynote' \mynote>}

cC = {\tag #'midiOut \mynoteDouble
\tag #'screenOut \mynoteExp }

music =
{
\time 3/4 \clef bass
\changePitch {a2} \cC
}

\score
{
\keepWithTag #'screenOut \music
\layout {}
}

\score
{
\keepWithTag #'midiOut \music
\layout {}
\midi {}
}

and in the attached file capture2 you can find the output for this second scenario.

Consider that:

- the variable cC will always contain a single note or a single chord

- I tried using changepitch but any other (possibly simpler) way is welcome

Any suggestion?

Thank you, g.

From:	Gianmaria Lari
Subject:	duration using variable
Date:	Wed, 27 Apr 2016 10:56:53 +0200