La gestione dei file MIDI mediante le funzioni esterne del API di Fluidsynth
Da Gambas-it.org - Wikipedia.
Versione del 8 gen 2016 alle 18:58 di Vuott (Discussione | contributi)
Mostriamo di seguito il codice per di un semplice applicativo per la riproduzione di file Midi.
Bisogna avere installato Jackd. Una volta lanciato l'applicativo, aprire Jackd e nella scheda "Audio" connettere il dispositivo "Fluidsynth", presente nella colonna "Clients leggibili/Porte d'uscita", al dispositivo "system" presente nella colonna "Clients scrivibili/Porte d'entrata".
Si dovrà, inoltre, individuare un file soundfont bank con estensione .sf2, da far caricare successivamente dalla funzione esterna "fluid_synth_sfload" per poter ottenere i suoni.
Private settings As Pointer Private synth As Pointer Private adriver As Pointer Private player As Pointer Private fileMidi As String Library "libfluidsynth:1.5.2" ' fluid_settings_t* new_fluid_settings(void) ---> Crea un nuovo oggetto Settings. Private Extern new_fluid_settings() As Pointer ' fluid_synth_t * new_fluid_synth (fluid_settings_t *settings) ---> Crea una nuova istanza FluidSynth. Private Extern new_fluid_synth(settP As Pointer) As Pointer ' fluid_player_t* new_fluid_player(fluid_synth_t * synth) ---> Crea un nuovo lettore MIDI. Private Extern new_fluid_player(synth As Pointer) As Pointer ' int fluid_settings_setintfluid_settings_t *settings, const char *name, int val) ---> Connette automaticamente il lettore Midi a Jack. Private Extern fluid_settings_setint(settP As Pointer, name As String, valI As Integer) As Integer ' fluid_audio_driver_t* new_fluid_audio_driver(fluid_settings_t * settings, fluid_synth_t * synth) ---> Crea un nuovo driver audio. Private Extern new_fluid_audio_driver(settings As Pointer, synth As Pointer) As Pointer ' int fluid_is_soundfont(const char * filename) ---> Controlla se il file caricato è effettivamente un file SoundFont. Private Extern fluid_is_soundfont($filename As String) As Integer ' int fluid_synth_sfload(fluid_synth_t * synth, const char * filename, nt reset_presets) ---> Carica file SoundFont. Private Extern fluid_synth_sfload(synth As Pointer, $filename As String, reset_presets As Integer) As Integer ' int fluid_is_midifile(const char * filename) ---> Controlla se il file caricato è un file MIDI. Private Extern fluid_is_midifile($fileMidi As String) As Integer ' int fluid_player_add(fluid_player_t * player, Const char * midifile) ---> Aggiunge un file MIDI alla coda del lettore. Private Extern fluid_player_add(player As Pointer, $fileMidi As String) As Integer ' int fluid_player_play(fluid_player_t * player) ---> Attiva la modalità esegui (play) al lettore MIDI, se non sta già eseguendo un Midi. Private Extern fluid_player_play(player As Pointer) As Integer ' int fluid_player_stop(fluid_player_t * player) ---> Attiva la modalità arresta (stop) al lettore MIDI. Private Extern fluid_player_stop(player As Pointer) As Integer ' int fluid_player_get_status(fluid_player_t * player) ---> Ottiene lo status del lettore MIDI. Private Extern fluid_player_get_status(player As Pointer) As Integer ' int fluid_player_all_notes_off(fluid_synth_t * synth, int chan) ---> Invia al lettore MIDI un comando di "All Notes Off". Private Extern fluid_synth_all_notes_off(synth As Pointer, valOff As Integer) As Integer ' int fluid_synth_all_sounds_off(fluid_synth_t * synth, int chan) ---> Invia al lettore MIDI un comando di "All Sounds Off". Private Extern fluid_synth_all_sounds_off(synth As Pointer, valOff As Integer) As Integer ' void delete_fluid_audio_driver(fluid_audio_driver_t * driver) ---> Elimina un'istanza di driver audio. Private Extern delete_fluid_audio_driver(driver As Pointer) ' int delete_fluid_player(fluid_player_t * player) ---> Elimna un'istanza di lettore MIDI. Private Extern delete_fluid_player(player As Pointer) As Integer ' int delete_fluid_synth(fluid_synth_t * synth) ---> Elimna un'istanza FluidSynth. Private Extern delete_fluid_synth(synth As Pointer) As Integer ' void delete_fluid_settings(fluid_settings_t * settings) ---> Elimina l'oggetto Settings. Private Extern delete_fluid_settings(settings As Pointer) Public Sub Form_Open() Dim i As Integer Dim filesbk As String filesbk = "/percorso/del/file/soundfont.sf2" settings = new_fluid_settings() synth = new_fluid_synth(settings) player = new_fluid_player(synth) i = fluid_settings_setint(settings, "audio.jack.autoconnect", 1) If i = 0 Then Error.Raise("Errore alla funzione 'fluid_settings_setint()' !") adriver = new_fluid_audio_driver(settings, synth) If IsNull(adriver) Then Error.Raise("Impossibile creare un driver audio !") i = fluid_is_soundfont(filesbk) If CBool(i) = False then Error.Raise("Il file non è un soundfont bank !") i = fluid_synth_sfload(synth, filesbk, 1) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_synth_sfload()' !") End Public Sub Button1_Click() Dim i As Integer i = fluid_player_add(player, fileMidi) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_player_add()' !") ' Avvia l'esecuzione del file Midi: i = fluid_player_play(player) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_player_play()' !") Do Wait 0.01 Loop Until fluid_player_get_status(player) <> 1 i = delete_fluid_player(player) If i < 0 Then Error.Raise("Errore alla funzione 'delete_fluid_player()' !") player = new_fluid_player(synth) End Public Sub Button2_Click() Dim i As Integer ' Arresta l'esecuzione del file Midi: i = fluid_player_stop(player) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_player_stop()' !") i = fluid_synth_all_notes_off(synth, -1) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_synth_all_notes_off()' !") i = fluid_synth_all_sounds_off(synth, -1) If i < 0 Then Error.Raise("Errore alla funzione 'fluid_synth_all_sounds_off()' !") End Public Sub Form_Close() delete_fluid_audio_driver(adriver) delete_fluid_player(player) delete_fluid_synth(synth) delete_fluid_settings(settings) End Public Sub MenuApri_Click() Dim i As Integer With Dialog .Title = "Apri file Midi..." .Filter = ["*.mid", "File Midi"] If .OpenFile() Then Return fileMidi = .Path End With i = fluid_is_midifile(fileMidi) If CBool(i) = False Then Error.Raise("Il file caricato non è un file Midi standard !") End