\version "2.11.62"

parenthps = #"
0 0 translate
45 45 scale
0 0 0 setrgbcolor
[] 0 setdash
1 setlinewidth
0 setlinejoin
0 setlinecap
newpath
0.0147465 0 moveto
0.011106 0.00351338 0.00916298 0.00598483 0.00710032 0.00978362 curveto
0.00248893 0.01832964 3e-008 0.02925362 3e-008 0.04074722 curveto
3e-008 0.05157272 0.00218483 0.06173772 0.00625033 0.07019282 curveto
0.00855727 0.07474937 0.01061993 0.07759971 0.0147465 0.08158922 curveto
0.0147465 0.07807584 lineto
0.00867816 0.06971302 0.00625033 0.05898344 0.00625033 0.04074724 curveto
0.00625033 0.02250984 0.00867816 0.01187244 0.0147465 0.00351344 curveto
0.0147465 6e-008 lineto
0.0147465 0 lineto
closepath
fill"

parenthL = \markup
{
   \with-dimensions #'(0 . 0.68) #'(0 . 3.67)
   \postscript #parenthps
}

parenthR = \markup { \rotate #180 \parenthL }

  
compoundTimeSigParenth = #(define-music-function
  (parser layout timesig compound) (list? list?)
  #{
    % graphical display
    \once \override Staff.TimeSignature #'stencil = #ly:text-interface::print
    \once \override Staff.TimeSignature #'text = #(markup
       #:override '(baseline-skip . 0) #:number 
            ;; First create the main time signature
           (#:line (#:left-align (#:center-column (
           (number->string (car $timesig))
           (number->string (cadr $timesig)))) 
           #:concat(#:vcenter parenthL #:hspace 0.2 
           ;; then the compound "numerator" part
           #:left-align (#:center-column ((#:concat (
           ;; list the additive portions of the time signature,
           ;; adding "+" between items.
           (make-line-markup (list-insert-separator
             (map (lambda (n)
                 (markup (number->string n)))
              $compound)
             (markup "+"))))) 
          ;; and lastly the "denominator" part
         (number->string (cadr $timesig)))) 
         #:hspace 0.2 #:vcenter parenthR))))

    % measure length + beaming
    \set Timing.timeSignatureFraction = #(cons (car $timesig) (cadr $timesig))
    \set Timing.beatLength = #(ly:make-moment 1 (cadr $timesig) 0 1)
    \set Timing.beatGrouping = $compound
    \set Timing.measureLength = #(ly:make-moment (car $timesig) (cadr $timesig) 0 1)
  #})