Fluidsynth should not reject unknown INFO chunks

[spessasus]

FluidSynth version

Copyright (C) 2000-2025 Peter Hanappe and others.
Distributed under the LGPL license.
SoundFont(R) is a registered trademark of Creative Technology Ltd.

FluidSynth executable version 2.4.6
Sample type=double

Describe the bug

SF2 2.04 specification, section 10.2:

10.2 Unknown Chunks
In parsing the RIFF structure, unknown but well formed chunks or sub-chunks may be encountered. Unknown chunks
within the INFO-list chunk should simply be ignored. Other unknown chunks or sub-chunks are illegal and should be
treated as structural errors.

I've created a test soundfont for my DMOD proposal and according to the specifications, it is still a valid file that should load. It only includes the extra DMOD chunk, yet fluidsynth rejects it, violating this section of the spec. I've specifically added it in the INFO-list because the spec allows to do so.

Expected behavior

The program should load the bank and play it as is, ignoring unknown INFO chunks. The current behavior is not to spec and eliminates the possibility of any extensions, like my DMOD proposal.

Steps to reproduce

1. Download the DMOD test soundfont
2. Attempt to load it with fluidsynth
3. fluidsynth: error: Invalid chunk id in INFO chunk

Additional context

I'm working on a soundfont/dls editor which also writes this chunk to an sf2 file. Having fluidsynth incorrectly reject it isn't good.

[derselbst]

Totally valid, and should be simple to fix. Remove the return here https://github.com/FluidSynth/fluidsynth/blob/94d195a564a08e89c396656b116734ea115476ae/src/sfloader/fluid_sffile.c#L748 and replace the error message with a warning. Im unable to do it atm.

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Message ID: ***@***.***>

[spessasus]

Alright, on it!

[spessasus]

I've created the PR, the DMOD bank works fine now.