Fast file renderer for non-realtime MIDI file rendering

Instead of creating an audio driver as described in section Loading and playing a MIDI file one may chose to use the file renderer, which is the fastest way to synthesize MIDI files.

fluid_settings_t* settings;
fluid_synth_t* synth;
fluid_player_t* player;
fluid_file_renderer_t* renderer;
 
settings = new_fluid_settings();
 
// specify the file to store the audio to
// make sure you compiled fluidsynth with libsndfile to get a real wave file
// otherwise this file will only contain raw s16 stereo PCM
fluid_settings_setstr(settings, "audio.file.name", "/path/to/output.wav");
 
// use number of samples processed as timing source, rather than the system timer
fluid_settings_setstr(settings, "player.timing-source", "sample");
 
// since this is a non-realtime scenario, there is no need to pin the sample data
fluid_settings_setint(settings, "synth.lock-memory", 0);
 
synth = new_fluid_synth(settings);
 
// *** loading of a soundfont omitted ***
 
player = new_fluid_player(synth);
fluid_player_add(player, "/path/to/midifile.mid");
fluid_player_play(player);
 
renderer = new_fluid_file_renderer (synth);
 
while (fluid_player_get_status(player) == FLUID_PLAYER_PLAYING)
{
    if (fluid_file_renderer_process_block(renderer) != FLUID_OK)
    {
        break;
    }
}
 
// just for sure: stop the playback explicitly and wait until finished
fluid_player_stop(player);
fluid_player_join(player);
 
delete_fluid_file_renderer(renderer);
delete_fluid_player(player);
delete_fluid_synth(synth);
delete_fluid_settings(settings);

Various output files types are supported, if compiled with libsndfile. Those can be specified via the settings object as well. Refer to the Audio driver settings documentation for more audio.file.* options.