mirror of https://github.com/ZDoom/fluidsynth.git
143 lines
4.5 KiB
Plaintext
143 lines
4.5 KiB
Plaintext
/*!
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\page Sequencer Using the MIDI sequencer
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FluidSynth's sequencer can be used to play MIDI events in a more flexible way
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than using the MIDI file player, which expects the events to be stored as
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Standard MIDI Files. Using the sequencer, you can provide the events one by
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one, with an optional timestamp for scheduling.
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The client program should first initialize the sequencer instance using the
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function new_fluid_sequencer2(). There is a complementary function
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delete_fluid_sequencer() to delete it. After creating the sequencer instance,
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the destinations can be registered using
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fluid_sequencer_register_fluidsynth() for the synthesizer destination, and
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optionally using fluid_sequencer_register_client() for the client destination
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providing a suitable callback function. It can be unregistered using
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fluid_sequencer_unregister_client(). After the initialization, events can be
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sent with fluid_sequencer_send_now() and scheduled to the future with
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fluid_sequencer_send_at(). The registration functions return identifiers,
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that can be used as destinations of an event using fluid_event_set_dest().
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The function fluid_sequencer_get_tick() returns the current playing position.
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A program may choose a new timescale in milliseconds using
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fluid_sequencer_set_time_scale().
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The following example uses the fluidsynth sequencer to implement a sort of
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music box. FluidSynth internal clock is used to schedule repetitive sequences
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of notes. The next sequence is scheduled on advance before the end of the
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current one, using a timer event that triggers a callback function. The
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scheduling times are always absolute values, to avoid slippage.
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\code
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#include "fluidsynth.h"
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fluid_synth_t* synth;
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fluid_audio_driver_t* adriver;
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fluid_sequencer_t* sequencer;
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short synthSeqID, mySeqID;
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unsigned int now;
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unsigned int seqduration;
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// prototype
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void seq_callback(unsigned int time, fluid_event_t* event, fluid_sequencer_t* seq, void* data);
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void createsynth()
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{
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fluid_settings_t* settings;
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settings = new_fluid_settings();
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fluid_settings_setint(settings, "synth.reverb.active", 0);
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fluid_settings_setint(settings, "synth.chorus.active", 0);
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synth = new_fluid_synth(settings);
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adriver = new_fluid_audio_driver(settings, synth);
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sequencer = new_fluid_sequencer2(0);
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// register synth as first destination
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synthSeqID = fluid_sequencer_register_fluidsynth(sequencer, synth);
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// register myself as second destination
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mySeqID = fluid_sequencer_register_client(sequencer, "me", seq_callback, NULL);
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// the sequence duration, in ms
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seqduration = 1000;
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}
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void deletesynth()
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{
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delete_fluid_sequencer(sequencer);
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delete_fluid_audio_driver(adriver);
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delete_fluid_synth(synth);
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}
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void loadsoundfont()
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{
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int fluid_res;
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// put your own path here
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fluid_res = fluid_synth_sfload(synth, "Inside:VintageDreamsWaves-v2.sf2", 1);
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}
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void sendnoteon(int chan, short key, unsigned int date)
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{
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int fluid_res;
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fluid_event_t *evt = new_fluid_event();
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fluid_event_set_source(evt, -1);
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fluid_event_set_dest(evt, synthSeqID);
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fluid_event_noteon(evt, chan, key, 127);
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fluid_res = fluid_sequencer_send_at(sequencer, evt, date, 1);
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delete_fluid_event(evt);
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}
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void schedule_next_callback()
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{
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int fluid_res;
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// I want to be called back before the end of the next sequence
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unsigned int callbackdate = now + seqduration/2;
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fluid_event_t *evt = new_fluid_event();
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fluid_event_set_source(evt, -1);
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fluid_event_set_dest(evt, mySeqID);
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fluid_event_timer(evt, NULL);
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fluid_res = fluid_sequencer_send_at(sequencer, evt, callbackdate, 1);
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delete_fluid_event(evt);
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}
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void schedule_next_sequence() {
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// Called more or less before each sequence start
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// the next sequence start date
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now = now + seqduration;
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// the sequence to play
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// the beat : 2 beats per sequence
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sendnoteon(0, 60, now + seqduration/2);
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sendnoteon(0, 60, now + seqduration);
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// melody
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sendnoteon(1, 45, now + seqduration/10);
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sendnoteon(1, 50, now + 4*seqduration/10);
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sendnoteon(1, 55, now + 8*seqduration/10);
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// so that we are called back early enough to schedule the next sequence
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schedule_next_callback();
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}
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/* sequencer callback */
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void seq_callback(unsigned int time, fluid_event_t* event, fluid_sequencer_t* seq, void* data) {
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schedule_next_sequence();
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}
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int main(void) {
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createsynth();
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loadsoundfont();
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// initialize our absolute date
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now = fluid_sequencer_get_tick(sequencer);
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schedule_next_sequence();
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sleep(100000);
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deletesynth();
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return 0;
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}
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\endcode
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*/
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