Differenze tra le versioni di "Eseguire un file Midi mediante le funzioni esterne del API di VLC"
Riga 74: | Riga 74: | ||
− | Library "<FONT Color=red>libSDL2-2.0:0. | + | Library "<FONT Color=red>libSDL2-2.0:0.3000.3</font>" |
Private Const SDL_INIT_AUDIO As Integer = 16 | Private Const SDL_INIT_AUDIO As Integer = 16 | ||
Riga 97: | Riga 97: | ||
m = libvlc_media_new_path(inst, "<FONT color=darkgreen>''/percorso/del/file.mid''</font>") | m = libvlc_media_new_path(inst, "<FONT color=darkgreen>''/percorso/del/file.mid''</font>") | ||
− | <FONT color=gray>' ''Crea un media | + | <FONT color=gray>' ''Crea un media play30er:''</font> |
mp = libvlc_media_player_new_from_media(m) | mp = libvlc_media_player_new_from_media(m) | ||
Riga 214: | Riga 214: | ||
− | Library "<FONT color=red>libSDL2-2.0:0. | + | Library "<FONT color=red>libSDL2-2.0:0.3000.3</font>" |
Private Const SDL_INIT_AUDIO As Integer = 16 | Private Const SDL_INIT_AUDIO As Integer = 16 | ||
Riga 346: | Riga 346: | ||
− | Library "<FONT color=red>libSDL2-2.0:0. | + | Library "<FONT color=red>libSDL2-2.0:0.3000.3</font>" |
Private Const SDL_INIT_AUDIO As Integer = 16 | Private Const SDL_INIT_AUDIO As Integer = 16 |
Versione delle 18:15, 3 giu 2024
La libreria LibVLC consente di eseguire anche file MIDI, purché si abbiano installati nel sistema anche:
- vlc-plugin-fluidsynth - le risorse dei plugin di FluidSynth per VLC;
- fluid-soundfont-gm - Fluid (R3) General MIDI SoundFont (GM);
- ovviamente lo stesso FluidSynth.
E' possibile eseguire dati Midi anche direttamente da internet.
Per creare in Gambas un'applicazione con la presente risorsa, si dovrà installare e richiamare la libreria condivisa "libvlc.so.5.6.1 ".
Indice
Esempio con applicazione grafica
Mostriamo di seguito un semplice esempio, nel quale si potrà avviare, arrestare, porre in pausa e riprendere l'esecuzione del file Midi:
Private inst As Pointer Private mp As Pointer Private m As Pointer Library "libvlc:5.6.1" Private Enum libvlc_NothingSpecial = 0, libvlc_Opening, libvlc_Buffering, libvlc_Playing, libvlc_Paused, libvlc_Stopped, libvlc_Ended, libvlc_Error ' libvlc_instance_t * libvlc_new (int argc, const char *const *argv) ' Create And initialize a libvlc instance. Private Extern libvlc_new(argc As Integer, argv As String[]) As Pointer ' libvlc_media_t * libvlc_media_new_path (libvlc_instance_t *p_instance, const char *path) ' Create a media for a certain file path. Private Extern libvlc_media_new_path(p_instance As Pointer, path As String) As Pointer ' libvlc_media_player_t * libvlc_media_player_new_from_media (libvlc_media_t *p_md) ' Create a Media Player object from a Media. Private Extern libvlc_media_player_new_from_media(p_md As Pointer) As Pointer ' int libvlc_media_player_play (libvlc_media_player_t * p_mi) ' Play the audio file. Private Extern libvlc_media_player_play(p_mi As Pointer) As Integer ' void libvlc_media_player_stop (libvlc_media_player_t * p_mi) ' Stop the audio file. Private Extern libvlc_media_player_stop(p_mi As Pointer) ' libvlc_time_t libvlc_media_player_get_length(libvlc_media_player_t *, libvlc_exception_t *) ' Get the current movie length (in ms). Private Extern libvlc_media_player_get_length(p_mi As Pointer, l_ex As Pointer) As Integer ' libvlc_time_t libvlc_media_player_get_time(libvlc_media_player_t * p_mi) ' Get the current movie time (in ms). Private Extern libvlc_media_player_get_time(p_mi As Pointer) As Integer ' libvlc_state_t libvlc_media_player_get_state(libvlc_media_player_t *p_mi) ' Get current movie state. Private Extern libvlc_media_player_get_state(p_mi As Pointer) As Integer ' void libvlc_media_player_pause (libvlc_media_player_t *p_mi) ' Toggle pause. Private Extern libvlc_media_player_pause(p_mi As Pointer) ' void libvlc_media_player_release (libvlc_media_player_t * p_mi) ' Release a media_player after use Decrement the reference count of a media player object. Private Extern libvlc_media_player_release(p_mi As Pointer) ' void libvlc_media_release (libvlc_media_t *p_md) ' Decrement the reference count of a media descriptor object. Private Extern libvlc_media_release(p_md As Pointer) ' libvlc_release (libvlc_instance_t * p_instance) ' Decrement the reference count of a libvlc instance, and destroy it if it reaches zero. Private Extern libvlc_release(p_instance As Pointer) Library "libSDL2-2.0:0.3000.3" Private Const SDL_INIT_AUDIO As Integer = 16 ' int SDL_Init(Uint32 flags) ' Initialize the SDL library. Private Extern SDL_Init(flags As Integer) As Integer ' void SDL_Quit(void) ' Clean up all initialized subsystems. Private Extern SDL_Quit() Public Sub Button1_Click() SDL_Init(SDL_INIT_AUDIO) ' Inizializza la libreria VLC: inst = libvlc_new(0, Null) ' Crea un nuovo oggetto multimedia: m = libvlc_media_new_path(inst, "/percorso/del/file.mid") ' Crea un media play30er: mp = libvlc_media_player_new_from_media(m) ' Avvia l'esecuzione del file Midi da parte del media player: libvlc_media_player_play(mp) Repeat TextLabel1.Text = "Durata: " & Str(Time(0, 0, 0, libvlc_media_player_get_length(mp, 0))) TextLabel2.Text = "<FONT Color=red>" & Str(Time(0, 0, 0, libvlc_media_player_get_time(mp))) Wait 0.01 Until libvlc_media_player_get_state(mp) > libvlc_Paused Chiude() End Public Sub Button2_Click() ' Arresta l'esecuzione del file Midi: libvlc_media_player_stop(mp) End Private Procedure Chiude() ' Chiude le librerie VLC e SDL: libvlc_media_player_release(mp) libvlc_media_release(m) libvlc_release(inst) SDL_Quit() End Public Sub ToggleButton1_Click() ' Pone in pausa o riprende (se già in pausa) l'esecuzione del file Midi: libvlc_media_player_pause(mp) End
Esempio con effetto video
In quest'altro esempio mostreremo un effetto video (Spectrum analyzer) di VLC, che rappresenta un "Analizzatore di spettro", all'interno di una DrawingArea
Private inst As Pointer Private mp As Pointer Library "libvlc:5.6.1" Private Enum libvlc_NothingSpecial = 0, libvlc_Opening, libvlc_Buffering, libvlc_Playing, libvlc_Paused, libvlc_Stopped, libvlc_Ended, libvlc_Error ' libvlc_instance_t * libvlc_new (int argc, const char *const *argv) ' Create And initialize a libvlc instance. Private Extern libvlc_new(argc As Integer, argv As String[]) As Pointer ' libvlc_media_t * libvlc_media_new_path (libvlc_instance_t *p_instance, const char *path) ' Create a media for a certain file path. Private Extern libvlc_media_new_path(p_instance As Pointer, path As String) As Pointer ' libvlc_media_player_t * libvlc_media_player_new_from_media (libvlc_media_t *p_md) ' Create a Media Player object from a Media. Private Extern libvlc_media_player_new_from_media(p_md As Pointer) As Pointer ' void libvlc_media_player_set_xwindow (libvlc_media_player_t *p_mi, uint32_t drawable) ' Set an X Window System drawable where the media player should render its video output. Private Extern libvlc_media_player_set_xwindow(p_mi As Pointer, drawable As Integer) ' int libvlc_media_player_play (libvlc_media_player_t * p_mi) ' Play the audio file. Private Extern libvlc_media_player_play(p_mi As Pointer) As Integer ' void libvlc_media_player_stop (libvlc_media_player_t * p_mi) ' Stop the audio file. Private Extern libvlc_media_player_stop(p_mi As Pointer) ' libvlc_time_t libvlc_media_player_get_length(libvlc_media_player_t *, libvlc_exception_t *) ' Get the current movie length (in ms). Private Extern libvlc_media_player_get_length(p_mi As Pointer, l_ex As Pointer) As Integer ' libvlc_time_t libvlc_media_player_get_time(libvlc_media_player_t * p_mi) ' Get the current movie time (in ms). Private Extern libvlc_media_player_get_time(p_mi As Pointer) As Integer ' libvlc_state_t libvlc_media_player_get_state(libvlc_media_player_t *p_mi) ' Get current movie state. Private Extern libvlc_media_player_get_state(p_mi As Pointer) As Integer ' void libvlc_media_player_pause (libvlc_media_player_t *p_mi) ' Toggle pause. Private Extern libvlc_media_player_pause(p_mi As Pointer) ' void libvlc_media_player_release (libvlc_media_player_t * p_mi) ' Release a media_player after use Decrement the reference count of a media player object. Private Extern libvlc_media_player_release(p_mi As Pointer) ' void libvlc_media_player_release (libvlc_media_player_t * p_mi) ' Release a media_player after use Decrement the reference count of a media player object. Private Extern libvlc_media_player_release(p_mi As Pointer) ' void libvlc_media_release (libvlc_media_t *p_md) ' Decrement the reference count of a media descriptor object. Private Extern libvlc_media_release(p_md As Pointer) ' libvlc_release (libvlc_instance_t * p_instance) ' Decrement the reference count of a libvlc instance, and destroy it if it reaches zero. Private Extern libvlc_release(p_instance As Pointer) Library "libSDL2-2.0:0.3000.3" Private Const SDL_INIT_AUDIO As Integer = 16 ' int SDL_Init(Uint32 flags) ' Initialize the SDL library. Private Extern SDL_Init(flags As Integer) As Integer ' void SDL_Quit(void) ' Clean up all initialized subsystems. Private Extern SDL_Quit() Public Sub Button1_Click() Dim ss As String[] Dim m As Pointer Dim id As Integer SDL_Init(SDL_INIT_AUDIO) ss = ["--audio-visual=visual", "--effect-list=spectrum"] ' Inizializza la libreria VLC: inst = libvlc_new(ss.Count, ss) ' Crea un nuovo oggetto multimedia: m = libvlc_media_new_path(inst, "/percorso/del/file.mid") ' Crea un media player: mp = libvlc_media_player_new_from_media(m) ' Per far mostrare l'effetto video "Analizzatore di spettro" nella "DrawingArea", ricaviamo il suo identificativo: id = DrawingArea1.Id ' Passiamo l'identificativo della finestra, nella quale dovrà essere mostrato l'effetto "Spectrum analyzer": libvlc_media_player_set_xwindow(mp, id) ' Avvia l'esecuzione del file Midi da parte del media player: libvlc_media_player_play(mp) Repeat TextLabel1.Text = "Durata: " & Str(Time(0, 0, 0, libvlc_media_player_get_length(mp, 0))) TextLabel2.Text = "<FONT Color=red>" & Str(Time(0, 0, 0, libvlc_media_player_get_time(mp))) Wait 0.01 Until libvlc_media_player_get_state(mp) > libvlc_Paused Chiude() End Public Sub Button2_Click() ' Arresta l'esecuzione del file Midi: libvlc_media_player_stop(mp) End Private Procedure Chiude() ' Chiude le librerie VLC e SDL: libvlc_media_player_release(mp) libvlc_media_release(m) libvlc_release(inst) SDL_Quit() End Public Sub ToggleButton1_Click() ' Pone in pausa o riprende (se già in pausa) l'esecuzione del file Midi: libvlc_media_player_pause(mp) End
Esempio con applicazione a riga di comando
Library "libvlc:5.6.1" Enum libvlc_NothingSpecial = 0, libvlc_Opening, libvlc_Buffering, libvlc_Playing, libvlc_Paused, libvlc_Stopped, libvlc_Ended, libvlc_Error ' libvlc_instance_t * libvlc_new (int argc, const char *const *argv) ' Create And initialize a libvlc instance. Private Extern libvlc_new(argc As Integer, argv As String) As Pointer ' libvlc_media_t * libvlc_media_new_path (libvlc_instance_t *p_instance, const char *path) ' Create a media for a certain Midi file path. Private Extern libvlc_media_new_path(p_instance As Pointer, path As String) As Pointer ' libvlc_media_player_t * libvlc_media_player_new_from_media (libvlc_media_t *p_md) ' Create a Media Player object from a Media. Private Extern libvlc_media_player_new_from_media(p_md As Pointer) As Pointer ' int libvlc_media_player_play (libvlc_media_player_t * p_mi) ' Play the Midi file. Private Extern libvlc_media_player_play(p_mi As Pointer) As Integer ' libvlc_time_t libvlc_media_get_duration(libvlc_media_t *p_md) ' Get duration (in ms) of media descriptor object item. Private Extern libvlc_media_get_duration(p_md As Pointer) As Long ' libvlc_time_t libvlc_media_player_get_time(libvlc_media_player_t * p_mi) ' Get the current movie time (in ms). Private Extern libvlc_media_player_get_time(p_mi As Pointer) As Integer ' libvlc_state_t libvlc_media_player_get_state(libvlc_media_player_t *p_mi) ' Get current movie state. Private Extern libvlc_media_player_get_state(p_mi As Pointer) As Integer ' void libvlc_media_player_release (libvlc_media_player_t * p_mi) ' Release a media_player after use Decrement the reference count of a media player object. Private Extern libvlc_media_player_release(p_mi As Pointer) ' void libvlc_media_release (libvlc_media_t *p_md) ' Decrement the reference count of a media descriptor object. Private Extern libvlc_media_release(p_md As Pointer) ' libvlc_release (libvlc_instance_t * p_instance) ' Decrement the reference count of a libvlc instance, and destroy it if it reaches zero. Private Extern libvlc_release(p_instance As Pointer) Library "libSDL2-2.0:0.3000.3" Private Const SDL_INIT_AUDIO As Integer = 16 ' int SDL_Init(Uint32 flags) ' Initialize the SDL library. Private Extern SDL_Init(flags As Integer) As Integer ' void SDL_Quit(void) ' Clean up all initialized subsystems. Private Extern SDL_Quit() Public Sub Main() Dim m, inst, mp As Pointer Dim l As Long SDL_Init(SDL_INIT_AUDIO) ' Inizializza la libreria VLC: inst = libvlc_new(0, Null) ' Crea un nuovo oggetto multimedia: m = libvlc_media_new_path(inst, "/percorso/del/file.mid") ' Crea un media player: mp = libvlc_media_player_new_from_media(m) ' Avvia l'esecuzione del file Midi da parte del media player: libvlc_media_player_play(mp) Repeat l = libvlc_media_get_duration(m) Until l > 0 Print "Durata: "; Time(0, 0, 0, l) While libvlc_media_player_get_state(mp) < libvlc_Stopped Write "\r \e[31m" & Str(Time(0, 0, 0, libvlc_media_player_get_time(mp))) Wait 0.01 Wend ' Chiude la libreria VLC: libvlc_media_player_release(mp) libvlc_media_release(m) libvlc_release(inst) SDL_Quit() End
Esecuzione on-line di un file Midi da una pagina web
Per eseguire on-line un file Midi dal collegamento presente in una pagina web, bisognerà:
1) assicurarsi che l'indirizzo web, ove è ospitato il file Midi da eseguire, inizi con l'acronimo del protocollo "http" e non con "https";
2) utilizzare la funzione "libvlc_media_new_location( )" al posto della funzione "libvlc_media_new_path( )".
Esempio:
media = libvlc_media_new_location(instance, "http://www.indirizzo/web/del/file.mid")