Riproduzione dell'audio di radio WEB con le funzioni esterne del API di GStreamer
Da Gambas-it.org - Wikipedia.
Versione del 16 feb 2017 alle 16:29 di Vuott (Discussione | contributi)
Le stazioni radio via WEB possono essere ascoltate utilizzando le risorse del API di GStreamer.
Uso del plug-in playbin
Private play As Pointer Library "libgstreamer-1.0" Private Const GST_STATE_NULL As Integer = 1 Private Const GST_STATE_PLAYING As Integer = 4 ' gst_init (&argc, &argv) ' Initializes the GStreamer library, setting up internal path lists, registering built-in elements, and loading standard plugins. Private Extern gst_init(argc As Integer, argv As Pointer) ' GstElement * gst_element_factory_make(const gchar *factoryname, Const gchar * name) ' Create a new element of the type defined by the given element factory. Private Extern gst_element_factory_make(factoryname As String, name As String) As Pointer ' void g_object_set(gpointer object, const gchar *first_property_name, ...) ' Sets properties on an object. Private Extern g_object_set(gobject As Pointer, key As String, value As String, nl As String) ' GstStateChangeReturn gst_element_set_state(GstElement *element, GstState state) ' Sets the state of the element. Private Extern gst_element_set_state(gstobject As Pointer, state As Integer) As Integer ' void gst_object_unref(gpointer object) ' Decrements the reference count on object . Private Extern gst_object_unref(gobject As Pointer) Public Sub Form_Open() Dim retI As Integer gst_init(0, 0) play = gst_element_factory_make("playbin", "play") ' Nel terzo argomento della seguente funzione va inserito ' l'indirizzo web del flusso di dati audio in tempo reale: g_object_set(play, "uri", "http://indirizzo/web/del/flusso/dati/della/radio4-web", Null) ' Avviamo la riproduzione audio della radio-web: retI = gst_element_set_state(play, GST_STATE_PLAYING) Print "Stato di cambiamento = "; retI End Public Sub Button1_Click() Dim retI As Integer ' Arrestiamo la riproduzione audio: retI = gst_element_set_state(play, GST_STATE_NULL) Print "Stato di cambiamento = "; retI gst_object_unref(play) End
Uso della funzione gst_parse_launch( ) e del plugin jackaudiosink
Per l'esecuzione del seguente codice è necessario avviare preliminarmente il programma Jack.
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_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 audio As Pointer Dim pos As Long Dim po As Date gst_init(0, 0) audio = gst_parse_launch("uridecodebin uri=http://indirizzo/della/radio/web/live ! audioconvert ! audioresample ! jackaudiosink", 0) ' Avviamo l'esecuzione audio della radio web: gst_element_set_state(audio, GST_STATE_PLAYING) While True gst_element_query_position(audio, GST_FORMAT_TIME, VarPtr(pos)) po = Date(0, 0, 0, 0, 0, 0, pos / 1000000) Write #File.Out, "\rTempo trascorso: " & po Wend gst_object_unref(audio) End