Eseguire file audio mediante le funzioni esterne del API di VLC
Da Gambas-it.org - Wikipedia.
Versione del 28 lug 2017 alle 17:14 di Vuott (Discussione | contributi)
La libreria LibVLC mette a disposizione funzioni e risorse anche per eseguire file audio.
I file audio eseguibili sono i seguenti:
- MP3;
- OGG;
- WAV;
- WMA.
E' possibile eseguire dati audio 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.5.5.0.
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 audio:
Private inst As Pointer
Private mp As Pointer
Library "libvlc:5.5.0"
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)
' 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 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/audio")
' Crea un media player:
mp = libvlc_media_player_new_from_media(m)
' Avvia l'esecuzione del file audio 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()
' Arresta l'esecuzione del file audio:
libvlc_media_player_stop(mp)
End
Private Procedure Chiude()
' Rilascia e chiude il media player:
libvlc_media_player_release(mp)
' Chiude la libreria VLC:
libvlc_release(inst)
End
Public Sub ToggleButton1_Click()
' Pone in pausa o riprende (se già in pausa) l'esecuzione del file audio:
libvlc_media_player_pause(mp)
End
Esempio con applicazione a riga di comando
Library "libvlc:5.5.0"
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
' 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, inst, 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/audio")
' Crea un media player:
mp = libvlc_media_player_new_from_media(m)
' Avvia l'esecuzione del file audio 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
