markup dynamics in a crescendo event

[Knute Snortum]

I'm trying to get a decrescendo to piano that starts with the dynamic "ffsf" which I create with markup, so like this code (except it doesn't work):

\version "2.18.2"

ffsf = \markup { \dynamic "ff" \dynamic "sf" }

\relative c' {

  c4 _\ffsf \> c c c | c c c c \p

}

I read about creating a crescendo event [1] but I only barely understand what's going on.  Still, I got to here:

crffsf =

#(make-music 'CrescendoEvent

             'span-direction START

             'span-type 'text

             'span-text "ffsf")

\relative c' {

  c4\crffsf d4 \! \> e4 f4 |

  g4 a4 b4 \p c4 |

}

...which gives me a text "ffsf" inline but not the dynamics.  How should I do this?

[1] http://lilypond.org/doc/v2.18/Documentation/snippets/expressive-marks#expressive-marks-dynamics-text-spanner-postfix

Knute Snortum

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