Estrarre tutte le tracce di un CD audio convertendole in un unico file WAV con la funzione 'gst parse launch()' di GStreamer: differenze tra le versioni
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' ''Sets the state of the element.''</font> | ' ''Sets the state of the element.''</font> | ||
Private Extern gst_element_set_state(gstelement As Pointer, state As Integer) As Integer | Private Extern gst_element_set_state(gstelement As Pointer, state As Integer) As Integer | ||
<FONT Color=gray>' ''gboolean gst_element_query_duration(GstElement *element, GstFormat format, gint64 *duration)'' | |||
' ''Queries an element for the total stream duration in nanoseconds.''</font> | |||
Private Extern gst_element_query_duration(gselement As Pointer, formatI As Integer, duration As Pointer) As Boolean | |||
<FONT Color=gray>' ''gboolean gst_element_query_position (GstElement *element, GstFormat format, gint64 *cur)'' | <FONT Color=gray>' ''gboolean gst_element_query_position (GstElement *element, GstFormat format, gint64 *cur)'' | ||
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'''Public''' Sub Main() | '''Public''' Sub Main() | ||
Dim | Dim pos, dur As Long | ||
Dim po, du As Date | |||
gst_init(0, 0) | gst_init(0, 0) | ||
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While True | While True | ||
gst_element_query_position(audio, GST_FORMAT_TIME, VarPtr( | gst_element_query_position(audio, GST_FORMAT_TIME, VarPtr(pos)) | ||
gst_element_query_duration(audio, GST_FORMAT_TIME, VarPtr(dur)) | |||
po = Date(0, 0, 0, 0, 0, 0, pos / 1000000) | |||
du = Date(0, 0, 0, 0, 0, 0, dur / 1000000) | |||
If (pos > 0) And (CStr(po) >= CStr(du)) Then Break | |||
Write #File.Out, "\rDurata: " & du & " " & "Tempo trascorso: " & po | |||
Wend | Wend | ||
Termina() | |||
'''End''' | '''End''' | ||
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'''Public''' Sub Application_Read() | '''Public''' Sub Application_Read() | ||
Dim s As String | |||
Input #File.In, s | |||
<FONT Color=gray>' '' | <FONT Color=gray>' ''Se viene inviato dalla console il carattere "t", termina l'applicazione:''</font> | ||
If "t" Then Termina() | |||
'''End''' | |||
'''Private''' Procedure Termina() | |||
gst_object_unref(audio) | |||
Print "\nEstrazione terminata." | |||
Quit | |||
'''End''' | '''End''' | ||
Versione delle 22:06, 5 mar 2016
La funzione esterna gst_parse_launch() della libreria GStreamer consente di costruire e gestire in modo semplice una pipeline GStreamer. La riga della pipeline gestita dalla funzione esterna gst_parse_launch() è un insieme di elementi separati da punti esclamativi (!). Le proprietà possono essere aggiunte agli elementi, sotto forma di: proprietà = valore.
Sarà necessario avere installata nel sistema e richiamare nell'applicazione Gambas la libreria dinamica condivisa: "libgstreamer-1.0"
Mostriamo un esempio pratico, nel quale verranno estratte e convertite in un unico file WAV tutte le tracce di un CD audio:
Private audio As Pointer
Library "libgstreamer-1.0"
Private Enum GST_STATE_VOID_PENDING = 0, GST_STATE_NULL, GST_STATE_READY, GST_STATE_PAUSED, GST_STATE_PLAYING
Private Const GST_FORMAT_TIME As Integer = 3
' gst_init (int *argc, char **argv[])
' Initializes the GStreamer library, setting up internal path lists, registering built-in elements, and loading standard plugins.
Private Extern gst_init(argc As Pointer, argv As Pointer)
' GstElement * gst_parse_launch (const gchar *pipeline_description, GError **error)
' Create a new pipeline based on command line syntax.
Private Extern gst_parse_launch(description As String, GError As Pointer) As Pointer
' GstStateChangeReturn gst_element_set_state(GstElement *element, GstState state)
' Sets the state of the element.
Private Extern gst_element_set_state(gstelement As Pointer, state As Integer) As Integer
' gboolean gst_element_query_duration(GstElement *element, GstFormat format, gint64 *duration)
' Queries an element for the total stream duration in nanoseconds.
Private Extern gst_element_query_duration(gselement As Pointer, formatI As Integer, duration As Pointer) As Boolean
' gboolean gst_element_query_position (GstElement *element, GstFormat format, gint64 *cur)
' Queries an element for the stream position in nanoseconds.
Private Extern gst_element_query_position(gstelement As Pointer, gstformat As Pointer, cur As Pointer) As Boolean
' void gst_object_unref(gpointer object)
' Decrements the reference count on object.
Private Extern gst_object_unref(gobject As Pointer)
Public Sub Main()
Dim pos, dur As Long
Dim po, du As Date
gst_init(0, 0)
audio = gst_parse_launch("cdparanoiasrc mode=continuous ! queue ! audioconvert ! wavenc ! filesink location=/percorso/del/file.wav", 0)
' Avviamo l'estrazione dell'intero CD audio:
gst_element_set_state(audio, GST_STATE_PLAYING)
While True
gst_element_query_position(audio, GST_FORMAT_TIME, VarPtr(pos))
gst_element_query_duration(audio, GST_FORMAT_TIME, VarPtr(dur))
po = Date(0, 0, 0, 0, 0, 0, pos / 1000000)
du = Date(0, 0, 0, 0, 0, 0, dur / 1000000)
If (pos > 0) And (CStr(po) >= CStr(du)) Then Break
Write #File.Out, "\rDurata: " & du & " " & "Tempo trascorso: " & po
Wend
Termina()
End
Public Sub Application_Read()
Dim s As String
Input #File.In, s
' Se viene inviato dalla console il carattere "t", termina l'applicazione:
If "t" Then Termina()
End
Private Procedure Termina()
gst_object_unref(audio)
Print "\nEstrazione terminata."
Quit
End