Differenze tra le versioni di "La gestione dei file MIDI mediante le funzioni esterne del API di VLC"
Da Gambas-it.org - Wikipedia.
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− | Per creare un'applicazione con la presente risorsa, si dovrà | + | Per creare in Gambas un'applicazione con la presente risorsa, si dovrà installare e richiamare la libreria dinamica e condivisa ''libvlc.so.5.4.0''. |
===Esempio con applicazione grafica=== | ===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 inst As Pointer | ||
Private mp As Pointer | Private mp As Pointer | ||
− | + | ||
Library "libvlc:5.4.0" | Library "libvlc:5.4.0" | ||
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<FONT color=gray>' ''libvlc_media_t * libvlc_media_new_path (libvlc_instance_t *p_instance, const char *path)'' | <FONT color=gray>' ''libvlc_media_t * libvlc_media_new_path (libvlc_instance_t *p_instance, const char *path)'' | ||
− | ' ''Create a media for a certain | + | ' ''Create a media for a certain file path.''</font> |
Private Extern libvlc_media_new_path(p_instance As Pointer, path As String) As Pointer | Private Extern libvlc_media_new_path(p_instance As Pointer, path As String) As Pointer | ||
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<FONT color=gray>' ''int libvlc_media_player_play (libvlc_media_player_t * p_mi)'' | <FONT color=gray>' ''int libvlc_media_player_play (libvlc_media_player_t * p_mi)'' | ||
− | ' ''Play the | + | ' ''Play the audio file.''</font> |
Private Extern libvlc_media_player_play(p_mi As Pointer) As Integer | Private Extern libvlc_media_player_play(p_mi As Pointer) As Integer | ||
<FONT color=gray>' ''void libvlc_media_player_stop (libvlc_media_player_t * p_mi)'' | <FONT color=gray>' ''void libvlc_media_player_stop (libvlc_media_player_t * p_mi)'' | ||
− | ' ''Stop the | + | ' ''Stop the audio file.''</font> |
Private Extern libvlc_media_player_stop(p_mi As Pointer) | Private Extern libvlc_media_player_stop(p_mi As Pointer) | ||
+ | |||
+ | <FONT color=gray>' ''libvlc_time_t libvlc_media_player_get_length(libvlc_media_player_t *, libvlc_exception_t *)'' | ||
+ | ' ''Get the current movie length (in ms).''</font> | ||
+ | Private Extern libvlc_media_player_get_length(p_mi As Pointer, l_ex As Pointer) As Integer | ||
<FONT color=gray>' ''libvlc_time_t libvlc_media_player_get_time(libvlc_media_player_t * p_mi)'' | <FONT color=gray>' ''libvlc_time_t libvlc_media_player_get_time(libvlc_media_player_t * p_mi)'' | ||
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' ''Get current movie state.''</font> | ' ''Get current movie state.''</font> | ||
Private Extern libvlc_media_player_get_state(p_mi As Pointer) As Integer | Private Extern libvlc_media_player_get_state(p_mi As Pointer) As Integer | ||
+ | |||
+ | <FONT color=gray>' ''void libvlc_media_player_pause (libvlc_media_player_t *p_mi)'' | ||
+ | ' ''Toggle pause.''</font> | ||
+ | Private Extern libvlc_media_player_pause(p_mi As Pointer) | ||
<FONT color=gray>' ''void libvlc_media_player_release (libvlc_media_player_t * p_mi)'' | <FONT color=gray>' ''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.''</font> | ' ''Release a media_player after use Decrement the reference count of a media player object.''</font> | ||
Private Extern libvlc_media_player_release(p_mi As Pointer) | Private Extern libvlc_media_player_release(p_mi As Pointer) | ||
− | + | ||
− | |||
− | |||
− | |||
− | |||
'''Public''' Sub Button1_Click() | '''Public''' Sub Button1_Click() | ||
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<FONT color=gray>' ''Inizializza la libreria VLC:''</font> | <FONT color=gray>' ''Inizializza la libreria VLC:''</font> | ||
− | + | inst = libvlc_new(0, Null) | |
<FONT color=gray>' ''Crea un nuovo oggetto multimedia:''</font> | <FONT color=gray>' ''Crea un nuovo oggetto multimedia:''</font> | ||
− | + | m = libvlc_media_new_path(inst, "''/percorso/del/file.mid''") | |
<FONT color=gray>' ''Crea un media player:''</font> | <FONT color=gray>' ''Crea un media player:''</font> | ||
− | + | mp = libvlc_media_player_new_from_media(m) | |
<FONT color=gray>' ''Avvia l'esecuzione del file Midi da parte del media player:''</font> | <FONT color=gray>' ''Avvia l'esecuzione del file Midi da parte del media player:''</font> | ||
− | + | libvlc_media_player_play(mp) | |
− | + | Do | |
− | + | TextLabel1.Text = "Durata: " & Str(Date(0, 0, 0, 0, 0, 0, libvlc_media_player_get_length(mp, 0))) | |
− | + | TextLabel2.Text = "<FONT Color=red>" & Str(Date(0, 0, 0, 0, 0, 0, libvlc_media_player_get_time(mp))) | |
− | + | Wait 0.01 | |
+ | Loop Until libvlc_media_player_get_state(mp) > libvlc_Paused | ||
+ | |||
+ | Chiude() | ||
'''End''' | '''End''' | ||
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'''Public''' Sub Button2_Click() | '''Public''' Sub Button2_Click() | ||
+ | |||
+ | Chiude() | ||
+ | |||
+ | '''End''' | ||
+ | |||
+ | |||
+ | '''Private''' Procedure Chiude() | ||
<FONT color=gray>' ''Arresta l'esecuzione del file Midi:''</font> | <FONT color=gray>' ''Arresta l'esecuzione del file Midi:''</font> | ||
− | + | libvlc_media_player_stop(mp) | |
<FONT color=gray>' ''Rilascia e chiude il media player:''</font> | <FONT color=gray>' ''Rilascia e chiude il media player:''</font> | ||
− | + | libvlc_media_player_release(mp) | |
− | + | ||
− | <FONT color=gray>' '' | + | ToggleButton1.Value = False |
− | + | ||
+ | '''End''' | ||
+ | |||
+ | |||
+ | '''Public''' Sub ToggleButton1_Click() | ||
+ | |||
+ | <FONT color=gray>' ''Pone in pausa o riprende (se già in pausa) l'esecuzione del file Midi:''</font> | ||
+ | libvlc_media_player_pause(mp) | ||
'''End''' | '''End''' | ||
+ | |||
Versione delle 14:17, 9 feb 2015
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 dinamica e condivisa libvlc.so.5.4.0.
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 Library "libvlc:5.4.0" 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) Public Sub Button1_Click() Dim m As Pointer ' 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) Do TextLabel1.Text = "Durata: " & Str(Date(0, 0, 0, 0, 0, 0, libvlc_media_player_get_length(mp, 0))) TextLabel2.Text = "<FONT Color=red>" & Str(Date(0, 0, 0, 0, 0, 0, libvlc_media_player_get_time(mp))) Wait 0.01 Loop Until libvlc_media_player_get_state(mp) > libvlc_Paused Chiude() End Public Sub Button2_Click() Chiude() End Private Procedure Chiude() ' Arresta l'esecuzione del file Midi: libvlc_media_player_stop(mp) ' Rilascia e chiude il media player: libvlc_media_player_release(mp) ToggleButton1.Value = False 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:5.4.0" 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_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) ' 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) Public Sub Main() Dim m As Pointer Dim inst As Pointer Dim mp As Pointer ' Inizializza la libreria VLC: inst = libvlc_new(0, Null) ' Crea un nuovo oggetto multimedia: m = libvlc_media_new_path(inst, "/percorso/del/file/Midi") ' 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) While libvlc_media_player_get_state(mp) < libvlc_Stopped Write #File.Out, Str(Date(0, 0, 0, 0, 0, 0, libvlc_media_player_get_time(mp))) & "\r" Wend ' Va in chiusura: ' Rilascia e chiude il media player: libvlc_media_player_release(mp) ' Chiude la libreria VLC: libvlc_release(inst) End
Riferimenti
- Il sito del API di LibVLC.
- Videolan Wiki - Midi