Differenze tra le versioni di "Ottenere un file audio da un file video con le funzioni esterne del API di VLC"
Da Gambas-it.org - Wikipedia.
Riga 48: | Riga 48: | ||
' ''Release a media_player after use.''</font> | ' ''Release a media_player after use.''</font> | ||
Private Extern libvlc_media_player_release(p_mi As Pointer) | Private Extern libvlc_media_player_release(p_mi As Pointer) | ||
+ | |||
+ | <FONT color=gray>' ''void libvlc_media_release (libvlc_media_t *p_md)'' | ||
+ | ' ''Decrement the reference count of a media descriptor object.''</font> | ||
+ | Private Extern libvlc_media_release(p_md As Pointer) | ||
<FONT Color=gray>' ''libvlc_release (libvlc_instance_t * p_instance)'' | <FONT Color=gray>' ''libvlc_release (libvlc_instance_t * p_instance)'' | ||
Riga 87: | Riga 91: | ||
<FONT Color=gray>' ''Chiude il media player, la libreria VLC ed il programma:''</font> | <FONT Color=gray>' ''Chiude il media player, la libreria VLC ed il programma:''</font> | ||
libvlc_media_player_release(mp) | libvlc_media_player_release(mp) | ||
+ | libvlc_media_release(m) | ||
libvlc_release(inst) | libvlc_release(inst) | ||
Versione delle 04:16, 31 lug 2017
La libreria VLC consente di poter ottenere un file audio da un file Video.
E' necessario aver installata nel proprio sistema e richiamare in Gambas la libreria dinamica condivisa: "libvlc.so.5.5.0"
Mostriamo un esempio pratico in ambiente grafico, in cui da un file video si otterrà un file audio di formato wav:
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(libvlc_instance_t *p_libvlc_instance) ' Create an empty Media Player object. Private Extern libvlc_media_player_new(p_libvlc_instance As Pointer) As Pointer ' void libvlc_media_player_set_media(libvlc_media_player_t *p_mi, libvlc_media_t *p_md) ' Set the media that will be used by the media_player. Private Extern libvlc_media_player_set_media(p_md As Pointer, mp As Pointer) ' int libvlc_media_player_play (libvlc_media_player_t * p_mi) ' Play. Private Extern libvlc_media_player_play(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 ' 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 ' void libvlc_media_player_release (libvlc_media_player_t * p_mi) ' Release a media_player after use. 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) Public Sub Main() Dim inst, mp, m As Pointer Dim ss As String[] Dim argc as Integer ' Vengono impostate le opzioni ed il percorso ove sarà salvato il file audio wav: ss = ["--sout=#transcode{acodec=s16l,ab=128,samplerate=44100, channels=2}:standard{access=file,mux=wav,dst=/tmp/audio.wav}"] ' Imposta il valore del 1° argomento della funzione "libvlc_new()": argc = 1 ' Inizializza la libreria VLC: inst = libvlc_new(argc, ss) ' Crea il media player: mp = libvlc_media_player_new(inst) ' Crea un nuovo oggetto multimedia. ' Nel secondo argomento della funzione va specificato il percorso del file video da cui ottenere il file audio wav: m = libvlc_media_new_path(inst, "/percorso/del/file/video") libvlc_media_player_set_media(mp, m) ' Avvia la realizzazione 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 ' Chiude il media player, la libreria VLC ed il programma: libvlc_media_player_release(mp) libvlc_media_release(m) libvlc_release(inst) End
Indice
Ottenere altri formati di file audio
Oltre al formato WAV è possibile ottenere qualche altro formato di file audio.
Formato audio MP3
Per ottenere un file audio di formato mp3, è necessario sostituire la stringa delle opzioni con la seguente:
ss = ["--sout=#transcode{acodec=mp3,ab=128,samplerate=44100, channels=2}:standard{access=file,mux=raw,dst=/tmp/audio.mp3}"]
Formato audio OggVorbis
Per ottenere un file audio di formato OggVorbis, è necessario sostituire la stringa delle opzioni con la seguente:
ss = ["--sout=#transcode{acodec=vorb,ab=96,channels=2}:standard{access=file,mux=ogg,dst=/tmp/audio.ogg}"]