Support of vorbis-compressed sf3 sound fonts

[derselbst]

Musescore 2.0 introduced a new soundfont format sf3
See: https://musescore.org/en/node/20818

I took the liberty to post this request from Fabian Greffrath [email protected] from
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=740710 into the ticket system of fluidsynth.

Musescore is widely used and created this new format as part of their version 2.0 delivery.
Would be great if this feature would be officially distributed by fluidsynth.

Reinhold

Reported by: z34rgfj35

Original Ticket: fluidsynth/tickets/142

[derselbst]

I have created the attached patch to add support for sound fonts in SF3 format with Ogg Vorbis compressed samples to FluidSynth. It is mostly a proof of concept but works well already. I'd be glad if this would lead to the inclusion of this feature in FluidSynth.

Original comment by: fabian_deb

[derselbst]

In the previous patch, I had an off-by-one error in the calculation of the sample sizes. In FluidSynth, sample->end points to the last valid point in a sample, not to the first point after. This means that all samples were calculated one byte too short.

Now, all samples are correctly decoded, i.e. there are no samples with sfinfo.frames == 0 anymore. This also means that the loopstart and loopend variables are now correctly set. Also, most of the quality loss that I originally blamed on the compression seems to be gone now.

Original comment by: fabian_deb

[fabiangreffrath]

See:
fabiangreffrath/fluidsynth-code-git@6a9e05e

[derselbst]

@fabiangreffrath Looks good. Feel free to create a pull request so this can be discussed. However, I currently dont think that this will make it into the upcoming 1.1.7 maintenance release.