SDL2_Mixer failed to initialize in MIDI format even has specified SDL2_MIXER_FORMATS=wav,mid

[ChinYikMing]

Version of emscripten/emsdk:
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.46 (1960782)

emcc CFLAGS

-sSDL2_MIXER_FORMATS=wav,mid \
-sUSE_SDL_MIXER=2

Error when SDL2_Mixer is initializing in MIDI format

Mix_Init failed: MIDI support not available

Upon examining the SDL2_Mixer source code, I discovered that the primary cause might be that one of the following interfaces is not initialized in array s_music_interfaces(source):

#ifdef MUSIC_MID_FLUIDSYNTH
    &Mix_MusicInterface_FLUIDSYNTH,
#endif
#ifdef MUSIC_MID_TIMIDITY
    &Mix_MusicInterface_TIMIDITY,
#endif
#ifdef MUSIC_MID_NATIVE
    &Mix_MusicInterface_NATIVEMIDI,
#endif

Therefore, the three MIDI music interfaces described above are not accessed when the load_music_type function is executed.

I think defining one of the macros MUSIC_MID_TIMIDITY, MUSIC_MID_NATIVE, or MUSIC_MID_FLUIDSYNTH could be the solution. Since I can't find any documentation about any of them, may I know how to define one of them when building my own project (for example, defined them in emcc's CFLAGS)? Or perhaps there is another way to handle this?

[ChinYikMing]

I found this port tool has defined MUSIC_MID_TIMIDITY.

[ChinYikMing]

Also, I have mounted the GUS patches mentioned in this README at "/etc/timidity"

emcc's CFLAGS:

--embed-file build/timidity@/etc/timidity

[ChinYikMing]

I think the issue is related to PR (#16556)

[ChinYikMing]

I've worked out the solution, which is that the following build flags need to be passed during the executable's linking phase so that the project can link the ported SDL_Mixer library. Originally, the build process of my project involved building many object files and then linking them together, however I missed to link the ported SDL_Mixer library.

emcc build flags:

-sSDL2_MIXER_FORMATS=wav,mid \
-sUSE_SDL_MIXER=2