Differenze tra le versioni di "Visualizzare un oscilloscopio di GStreamer mediante la funzione 'gst parse launch()' durante l'esecuzione di un file Midi"
Da Gambas-it.org - Wikipedia.
| Riga 60: | Riga 60: | ||
tm = Now | tm = Now | ||
| − | + | ||
Repeat | Repeat | ||
l = DateDiff(tm, Now, gb.Millisecond) | l = DateDiff(tm, Now, gb.Millisecond) | ||
| Riga 66: | Riga 66: | ||
Wait 0.001 | Wait 0.001 | ||
Until l >= durata / 1000000 | Until l >= durata / 1000000 | ||
| − | + | ||
gst_object_unref(midi) | gst_object_unref(midi) | ||
Print "\nEsecuzione terminata." | Print "\nEsecuzione terminata." | ||
Versione delle 15:19, 13 gen 2024
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 condivisa: "libgstreamer-1.0 ".
Usando i plugin "wavescope" o "monoscope" unitamente a "autoaudiosink" all'interno della riga della pipeline della funzione "gst_parse_launch()", è possibile scegliere la visualizzazione di due tipi diversi di oscilloscopio attivo durante l'esecuzione di un file Midi.
Uso del plugin wavescope
Mostriamo un esempio pratico usando i plugin "wavescope" e "autoaudiosink" all'interno della riga della pipeline della funzione gst_parse_launch():
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 *duration)
' Queries an element for the total stream position in nanoseconds.
Private Extern gst_element_query_position(gstelement As Pointer, gstformat As Pointer, position 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 midi As Pointer
Dim volume As Float
Dim durata, l As Long
Dim tm As Date
gst_init(0, 0)
midi = gst_parse_launch("filesrc location=/percorso/del/file.mid ! midiparse ! fluiddec ! tee name=t " &
"! queue ! audioconvert ! wavescope style=3 ! video/x-raw, width=1000 ! videoconvert ! ximagesink t. " &
"! queue ! audioconvert ! m. t. ! queue ! volume volume=7.0 ! autoaudiosink", 0)
' Avviamo l'esecuzione del file midi:
gst_element_set_state(midi, GST_STATE_PLAYING)
Repeat
gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata))
Wait 0.01
Until durata > -1
tm = Now
Repeat
l = DateDiff(tm, Now, gb.Millisecond)
Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, l)
Wait 0.001
Until l >= durata / 1000000
gst_object_unref(midi)
Print "\nEsecuzione terminata."
End
Uso del plugin monoscope
Mostriamo un esempio pratico usando i plugin "monoscope" e "autoaudiosink" all'interno della riga della pipeline della funzione gst_parse_launch():
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 *duration)
' Queries an element for the total stream position in nanoseconds.
Private Extern gst_element_query_position(gstelement As Pointer, gstformat As Pointer, position 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 midi As Pointer
Dim volume As Float
Dim durata, l As Long
Dim tm As Date
gst_init(0, 0)
midi = gst_parse_launch("filesrc location=/percorso/del/file.mid ! midiparse ! fluiddec ! " &
"tee name=t ! queue ! audioconvert ! monoscope ! ximagesink ! queue ! m. t. ! " &
"queue ! volume volume=7.0 ! autoaudiosink", 0)
' Avviamo l'esecuzione del file Midi:
gst_element_set_state(midi, GST_STATE_PLAYING)
Repeat
gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata))
Wait 0.01
Until durata > -1
tm = Now
Repeat
l = DateDiff(tm, Now, gb.Millisecond)
Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, l)
Wait 0.001
Until l >= durata / 1000000
gst_object_unref(midi)
Print "\nEsecuzione terminata."
End
Riferimenti
- http://docs.gstreamer.com/display/GstSDK/gst-launch
- https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-bad-plugins/html/gst-plugins-bad-plugins-wavescope.html
- https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-good-plugins/html/gst-plugins-good-plugins-monoscope.html
- http://gstreamer.freedesktop.org/
- http://gstreamer.com/
