How about:
\version "2.19.83"
\layout {
\context {
\Staff
\override OttavaBracket.stencil = #ly:line-spanner::print
\override OttavaBracket.bound-details =
#`((left . ((text . ,#{ \markup\concat\italic { "8" \raise #.8 \tiny "va" } #})
(Y . 0)
(stencil-align-dir-y . ,UP)
))
(right . ((Y . 0)
(padding . -1)
(text . ,(make-draw-line-markup (cons 0 -1.5))))))
\override OttavaBracket.left-bound-info =
#ly:line-spanner::calc-left-bound-info-and-text
\override OttavaBracket.right-bound-info =
#ly:line-spanner::calc-right-bound-info
}
}
{
\ottava #1
c'' 4 4 4 4
}
Cheers,
Pierre