The midi output does not produce arpeggio midi sound.
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snippet
\version "2.13.59"
\include "english.ly"
TimeKey = { \time 4/4 \key ef \major }
PianoRHand = \relative c' {
<bf g'>8 ef4 <bf g'>8 <af af'>8 ef'4 <af, af'>8 | %bar 01
<bf bf'>8 ef4 <bf bf'>8 <c af'>8 <ef c'>4 <af, ef'>8 | %bar 02
<bf g'>8 g4 <bf g'>8 <af f'>4 <f ef'>8 <af c>8~ \break %bar 03
<af
c>2 <ef'' af bf ef>2\arpeggio | %bar 04
<bf, g'>8 ef4 <bf g'>8 <af af'>8 ef'4 <af, af'>8 | %bar 05
<bf bf'>8 ef4 <bf bf'>8 <c af'>8 <ef c'>4 <c af'>8 | %bar 06
<ef g>8 <g, ef'>4 <bf g'>8 <af~ f'>4 <af ef'>8 <d, bf'>8~ \break %bar 07
<d bf'>2 <bf'' bf'>2\arpeggio | %bar 08
}
PianoLHand = \relative c {
<< {bf2 c2} \\ {ef,1} >> | %bar 01
<< {df'2 cf2} \\ {ef,1} >> | %bar 02
<ef bf'>2 <df af'~>4. <af ef' af>8~ \break %bar 03
<af ef' af>1 | %bar 04
<< {bf'2 c2} \\ {ef,1} >> | %bar
05
<< {df'2 c2} \\ {ef,1} >> | %bar 06
<c c'>2 <f bf>4. <bf, f'>8~ \break %bar 07
<bf f'>1 | %bar 08
}
\score {
\new GrandStaff = "GrandStaff_score"
<<
\new ChoirStaff <<
>>
\new PianoStaff <<
\new Staff = "RH" { \TimeKey \PianoRHand }
\new Staff = "LH" { \TimeKey \clef bass \PianoLHand }
>>
>>
\layout { }
\midi { }
}