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 28: | Riga 28: | ||
' ''Queries an element For the total stream duration In nanoseconds.''</font> | ' ''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 | 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 *duration)'' | ||
| + | ' ''Queries an element for the total stream position in nanoseconds.''</font> | ||
| + | Private Extern gst_element_query_position(gstelement As Pointer, gstformat As Pointer, position As Pointer) As Boolean | ||
<FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | <FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | ||
| Riga 34: | Riga 38: | ||
| − | + | Public Sub Main() | |
Dim midi As Pointer | Dim midi As Pointer | ||
Dim volume As Float | Dim volume As Float | ||
| − | Dim durata As Long | + | Dim durata, pos As Long |
| − | |||
| − | |||
gst_init(0, 0) | gst_init(0, 0) | ||
| − | midi = gst_parse_launch("filesrc location=<FONT Color= | + | midi = gst_parse_launch("filesrc location=<FONT Color=darkgreen>''/percorso/del/file.mid''</font> ! midiparse ! fluiddec ! tee name=t " & |
"! queue ! audioconvert ! wavescope style=3 ! video/x-raw, width=1000 ! videoconvert ! ximagesink 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) | "! queue ! audioconvert ! m. t. ! queue ! volume volume=7.0 ! autoaudiosink", 0) | ||
| Riga 53: | Riga 55: | ||
Repeat | Repeat | ||
gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata)) | gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata)) | ||
| − | + | Wait 0.01 | |
| − | Until | + | Until durata > -1 |
| − | + | ||
| − | |||
| − | |||
Repeat | Repeat | ||
| − | + | gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos)) | |
| − | Write "\r\e[0mDurata: " & | + | Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, pos / 1000000) |
Wait 0.001 | Wait 0.001 | ||
| − | Until | + | Until pos >= durata |
gst_object_unref(midi) | gst_object_unref(midi) | ||
Print "\nEsecuzione terminata." | Print "\nEsecuzione terminata." | ||
| − | + | End | |
| Riga 92: | Riga 92: | ||
' ''Queries an element For the total stream duration In nanoseconds.''</font> | ' ''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 | 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 *duration)'' | ||
| + | ' ''Queries an element for the total stream position in nanoseconds.''</font> | ||
| + | Private Extern gst_element_query_position(gstelement As Pointer, gstformat As Pointer, position As Pointer) As Boolean | ||
<FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | <FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | ||
| Riga 98: | Riga 102: | ||
| − | + | Public Sub Main() | |
Dim midi As Pointer | Dim midi As Pointer | ||
Dim volume As Float | Dim volume As Float | ||
| − | Dim durata As Long | + | Dim durata, pos As Long |
| − | |||
| − | |||
gst_init(0, 0) | gst_init(0, 0) | ||
| − | midi = gst_parse_launch("filesrc location=<FONT Color= | + | midi = gst_parse_launch("filesrc location=<FONT Color=darkgreen>''/percorso/del/file.mid''</font> ! midiparse ! fluiddec ! " & |
"tee name=t ! queue ! audioconvert ! monoscope ! ximagesink ! queue ! m. t. ! " & | "tee name=t ! queue ! audioconvert ! monoscope ! ximagesink ! queue ! m. t. ! " & | ||
"queue ! volume volume=7.0 ! autoaudiosink", 0) | "queue ! volume volume=7.0 ! autoaudiosink", 0) | ||
| Riga 117: | Riga 119: | ||
Repeat | Repeat | ||
gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata)) | gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata)) | ||
| − | + | Wait 0.01 | |
| − | Until | + | Until durata > -1 |
| − | + | ||
| − | |||
| − | |||
Repeat | Repeat | ||
| − | + | gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos)) | |
| − | Write "\r\e[0mDurata: " & | + | Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, pos / 1000000) |
Wait 0.001 | Wait 0.001 | ||
| − | Until | + | Until pos >= durata |
gst_object_unref(midi) | gst_object_unref(midi) | ||
Print "\nEsecuzione terminata." | Print "\nEsecuzione terminata." | ||
| − | + | End | |
Versione delle 04:06, 12 dic 2023
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, pos As Long
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
Repeat
gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos))
Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, pos / 1000000)
Wait 0.001
Until pos >= durata
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, pos As Long
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
Repeat
gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos))
Write "\r\e[0mDurata: " & Time(0, 0, 0, durata / 1000000) & " Pos. \e[31m" & Time(0, 0, 0, pos / 1000000)
Wait 0.001
Until pos >= durata
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/
