repeat ottava

I have a fragment that needs to be repeated twice with alternate ending and the second time one octave higher. The following is an example that would be ok...

\version "2.19.52"

\score {
{
\mark "2nd time 8va"
\repeat volta 2 {c' d' e' f'}
\alternative {{a a a a}{b b b b}}
}
\layout {}
}

...but I need to generate the midi too. What can I do? Should I avoid "repeat volta", use variable and a midi and layout score? This is what I did:

\version "2.19.52"

frag = {c' d' e' f'}
alta = {a a a a}
altb = {b b b b}

music = {
\mark "2nd time 8va"
\repeat volta 2 \frag
\alternative {\alta \altb}
}

\score {
\music
\layout {}
}

musicmidi = {
\mark "2nd time 8va"
\frag
\alta
\transpose c c' {
\frag \altb
}
}

\score {
\musicmidi
\layout {}
}

Does exist any better way to do it?

From:	Gianmaria Lari
Subject:	repeat ottava
Date:	Tue, 28 Feb 2017 10:56:50 +0100