Native DLS support in 2.5.0 gives me "Not a SoundFont file" error but loads

[DominusExult]

in Exult we have FluidSynth support and I've just enabled DLS loading as the built in DLS support is kind of a sure shot that FluidSynth has it (we query the FS version).
But either we need another way to load DLS files than sf2 files or we are doing it wrong:

Trying config specified Midi driver: `FluidSynth'
Compiled with FluidSynth 2.5.0, using library: 2.5.0
fluidsynth: error: Not a SoundFont file
Loaded sound font 'data/gs_instruments.dls'

(the error comes from fluidsynth/src/sfloader/fluid_sffile.c the other messages are ours).
We are using fluid_synth_sfload() and that's where the error pops up. AFAICT it still loads the dls file and I can hear the difference when I use other dls files.
Our code is at https://github.com/exult/exult/blob/master/audio/midi_drivers/FluidSynthMidiDriver.cpp#L217 (and header at https://github.com/exult/exult/blob/master/audio/midi_drivers/FluidSynthMidiDriver.h).

So is it our fault or FS' fault? :)

[derselbst]

This behavior is expected. By default, there are two loaders in fluidsynth: The SF2 and the DLS loader. fluid_synth_sfload first tries the SF2 loader. It fails and prints an error. Then it tries the DLS loader and succeeds. fluid_synth_sfload will return the ID.

I admit this behavior is confusing. It might be fixed in a future version.

[DominusExult]

Thanks, that is reassuring :)

Something else, for our iOS port I created an Xcode project file to build fluidsynth as a library to link against. For now it is outside of the fluidsynth source but it could be easily adapted to be called from within (similar to SDL's Xcode project file).

[derselbst]

Ok, however, I see no benefit in adding a project file to our repo. I won't be using nor maintaining it. It provides no benefit, as we won't see if the build breaks. Yet, people will complain to me that this project file can no longer be used for whatever reasons.

So CI pipeline yes, sole project file nope. You're welcome to link it & document it in our wiki. Similar to what I did for Android.

[DominusExult]

I see your point and documenting is a good way to let people know without leaving you the maintenance burden.

[pedrolcl]

We had, long time ago, Visual Studio projects in the source tree, and also a Macintosh OS 9 project. Both were removed after the migration to CMake. I don't see as well the advantage of adding a Xcode project to the source tree, because CMake already provides a generator for Xcode:

$ cmake -S <sources-dir> -B <build-dir> -G Xcode

Like the Visual Studio, makefiles or ninja generators, it is one of the many available generators in CMake.

I don't use this generator myself, so please report if it is not working for Fluidsynth.

[DominusExult]

I‘ll have to try again. Last time I used it, it failed miserably. Party because the extra tables generation step, even though that is gone now, there is the extra clone gcem step 🤷‍♂️
Generally I have never had much success with Cmake‘s Xcode project generation. It almost never goes smooth and the more elaborate the bigger chance of failing there is.

[pedrolcl]

If it fails, please provide the generator standard error/output and the generated files. They may be useful in order to fix the failures.