libfluidsynth  2.0.1
fluidsynth_metronome.c

Example of a simple metronome using the MIDI sequencer API

/* FluidSynth Metronome - Sequencer API example
*
* This code is in the public domain.
*
* To compile:
* gcc -o fluidsynth_metronome -lfluidsynth fluidsynth_metronome.c
*
* To run:
* fluidsynth_metronome soundfont [beats [tempo]]
*
* [Pedro Lopez-Cabanillas <plcl@users.sf.net>]
*/
#include <stdlib.h>
#include <stdio.h>
#include <fluidsynth.h>
fluid_audio_driver_t *audiodriver;
fluid_sequencer_t *sequencer;
short synth_destination, client_destination;
unsigned int time_marker;
/* default tempo, beats per minute */
#define TEMPO 120
unsigned int note_duration = 60000 / TEMPO;
/* metronome click/bell */
unsigned int weak_note = 33;
unsigned int strong_note = 34;
/* number of notes in one pattern */
unsigned int pattern_size = 4;
/* prototype */
void
sequencer_callback(unsigned int time, fluid_event_t *event,
fluid_sequencer_t *seq, void *data);
/* schedule a note on message */
void
schedule_noteon(int chan, short key, unsigned int ticks)
{
fluid_event_set_dest(ev, synth_destination);
fluid_event_noteon(ev, chan, key, 127);
fluid_sequencer_send_at(sequencer, ev, ticks, 1);
}
/* schedule a timer event (shall trigger the callback) */
void
schedule_timer_event()
{
fluid_event_set_dest(ev, client_destination);
fluid_event_timer(ev, NULL);
fluid_sequencer_send_at(sequencer, ev, time_marker, 1);
}
/* schedule the metronome pattern */
void
schedule_pattern()
{
int i, note_time;
note_time = time_marker;
for(i = 0; i < pattern_size; ++i)
{
schedule_noteon(9, i ? weak_note : strong_note, note_time);
note_time += note_duration;
}
time_marker = note_time;
}
void
sequencer_callback(unsigned int time, fluid_event_t *event,
fluid_sequencer_t *seq, void *data)
{
schedule_timer_event();
schedule_pattern();
}
void
usage(char *prog_name)
{
printf("Usage: %s soundfont.sf2 [beats [tempo]]\n", prog_name);
printf("\t(optional) beats: number of pattern beats, default %d\n",
pattern_size);
printf("\t(optional) tempo: BPM (Beats Per Minute), default %d\n", TEMPO);
}
int
main(int argc, char *argv[])
{
int n;
fluid_settings_t *settings;
settings = new_fluid_settings();
if(argc < 2)
{
usage(argv[0]);
}
else
{
/* create the synth, driver and sequencer instances */
synth = new_fluid_synth(settings);
audiodriver = new_fluid_audio_driver(settings, synth);
sequencer = new_fluid_sequencer();
/* register the synth with the sequencer */
synth_destination = fluid_sequencer_register_fluidsynth(sequencer,
synth);
/* register the client name and callback */
client_destination = fluid_sequencer_register_client(sequencer,
"fluidsynth_metronome", sequencer_callback, NULL);
/* load a SoundFont */
n = fluid_synth_sfload(synth, argv[1], 1);
if(n != -1)
{
if(argc > 2)
{
n = atoi(argv[2]);
if(n > 0)
{
pattern_size = n;
}
}
if(argc > 3)
{
n = atoi(argv[3]);
if(n > 0)
{
note_duration = 60000 / n;
}
}
/* get the current time in ticks */
time_marker = fluid_sequencer_get_tick(sequencer);
/* schedule patterns */
schedule_pattern();
schedule_timer_event();
schedule_pattern();
/* wait for user input */
printf("press <Enter> to stop\n");
n = getchar();
}
/* clean and exit */
}
return 0;
}