% tomado de http://lsr.dsi.unimi.it/LSR/Item?id=204
rhythmMarkCStaffReduce = #-4
rhythmMarkCLabelFontSize = #-2

rhythmMarkC = #(define-music-function (parser location label musicI musicII ) (string? ly:music? ly:music?)
   #{
      \mark \markup
      {
        \combine

          \line {
            \hspace #0
            \translate #'(-0.1 . -3.25) \italic \fontsize #rhythmMarkCLabelFontSize $label
          } % end Line

          \line \vcenter {

              \score {                 % 1st column in line

                \new Staff \with {
                  fontSize = #rhythmMarkCStaffReduce
                  \override StaffSymbol #'staff-space = #(magstep rhythmMarkCStaffReduce)
                  \override StaffSymbol #'line-count = #0 
                  \override VerticalAxisGroup #'Y-extent = #'(0 . 0)  % td
                }

                \relative { \stemUp $musicI }

                \layout {
                  ragged-right= ##t
                  indent = 0
                  \context {
                    \Staff
                    \remove "Clef_engraver"
                    \remove "Time_signature_engraver" }
                } % layout

              } % 1st score

              \hspace #-0.1            % 2nd column in line

                                       % 3rd column in line
              \italic \fontsize #rhythmMarkCStaffReduce "="

              \score {                 % 4th column in line

                \new Staff \with {
                  fontSize = #rhythmMarkCStaffReduce
                  \override StaffSymbol #'staff-space = #(magstep rhythmMarkCStaffReduce)
                  \override StaffSymbol #'line-count = #0 
                  \override VerticalAxisGroup #'Y-extent = #'(0 . 0)  % td
                }

                \relative {
                  \stemUp $musicII
                }

                \layout {
                  ragged-right= ##t
                  indent = 0
                  \context {
                    \Staff
                    \remove "Clef_engraver"
                    \remove "Time_signature_engraver" }
                } % layout

              } % 2nd score end

            } % line end
          % end combine
        } % markup end
   #})

%%% predefined ly:music-Variables for use
%%% in function rhythmMark and rhythmMarkC
%%% ============================================================
rhyMarkI = { b'1*1/8 }

rhyMarkII = { b'2*1/4 }

rhyMarkIV = { b'4*1/2 }

rhyMarkEighth = { b'8 }

rhyMarkIIEighths = {
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 4) % tight
  \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 3 16) % even
  b'8[ b8]
}
rhyMarkTriplets = {
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 2) % super-tight
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 4) % tight
  \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 3 16) % even
  \times 2/3 { b'4 b8 }
}
rhyMarkSlurredTriplets = {
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 4) % tight
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 5 32) % slighty tighter as even
  \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 8) % even
  \times 2/3 { b'8 ~ b8 b8 }
}
rhyMarkDottedEighths = {
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 4) % tight
  \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 3 16) % even
  % \override Score.SpacingSpanner #'common-shortest-duration = #(ly:make-moment 1 8) % loose
  { b'8.[ b16*2] }
}

{ b1   \rhythmMarkC #"" \rhyMarkEighth \rhyMarkEighth b1 }