How to change the name of the MIDI file ?

[Louis Bettens]

Hello everybody,
Tiny example : try.ly :
\version "2.12.3"

\book {
  \score {
    %first arpeggio
    \relative c' { c e g c }
    \midi { }
  }
  \score {
    %second arpeggio
    \relative c' { d fis a d }
    \midi { }
  }
}

The midi output of the first arpeggio goes in "try.midi" and the second in
"try-1.midi".
I would like to specify a filename for each of these outputs ( for example
"arpeggio-C.midi" and "arpeggio-D.midi" )
Perhaps something in the midi block ?
Is it possible ?
Thank you for help !