I know this question was asked about a thousand times....

[Valentin Villenave]

...but since I consider myself as a newbie here, I hope you won't mind :)

Here am I : I've (almost) written a whole opera under Sibelius 3, and
I've been trying for ages to switch to Libre software, I mean our
favorite Lilypond forever...

The music I'm writing from now on is entirely genuine Lilypond-coded
(took me a couple hours a day during one month to learn but i'm done).
My question is : how about the music I wrote _before_ that, the tons
of .sib files on my HD ? Shall I rewrite it from scratch ? Is there
any way to spare me months and months of hard working ?

I tried MIDI export, I've also tried (actually I BOUGHT it) the Dolet
MusicXML export plugin. But it's still very very weak, and make a lot
of things disappear. I've even tried insane solutions, like printing
scores in PDF, and using some music-scanning software to recover it...
let me tell you : it's ugly.

The Makemusic Sibelius and Recordare guys are certainly doing great,
but gosh !! The hell with closed-source software !!
I know .sib files are compressed and somehow encrypted, and therefore
quite difficult to "disassemble" ; is there any sponsoring stuff to
make it possible however ?

Or is there any other advice anyone can give me ?
Thank you everybody. By the way, I find the Lilypond community is one
of the nicest I've ever met :)