Differenze tra le versioni di "Visualizzare uno spettroscopio di GStreamer mediante la funzione 'gst parse launch()' durante l'esecuzione di un file Midi"
Da Gambas-it.org - Wikipedia.
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Mostriamo un esempio pratico: | Mostriamo un esempio pratico: | ||
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Library "libgstreamer-1.0" | Library "libgstreamer-1.0" | ||
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' ''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 | ||
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<FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | <FONT Color=gray>' ''void gst_object_unref(gpointer object)'' | ||
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'''Public''' Sub Main() | '''Public''' Sub Main() | ||
| − | Dim | + | Dim midi As Pointer |
| − | Dim | + | Dim volume As Float |
| − | + | Dim durata As Long | |
| − | + | Dim dur, tempus As Date | |
| + | Dim dd As Integer | ||
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| + | gst_init(0, 0) | ||
| − | + | midi = gst_parse_launch("filesrc location=<FONT Color=gray>''/percorso/del/file.mid''</font> ! midiparse ! fluiddec ! tee name=t " & | |
| − | + | "! queue ! audioconvert ! spectrascope ! video/x-raw, width=1000, height=500! " & | |
| − | + | "videoconvert ! autovideosink ! queue ! audioconvert! m. t. ! queue ! " & | |
| + | "volume volume=7.0 ! autoaudiosink", 0) | ||
<FONT Color=gray>' ''Avviamo l'esecuzione del file Midi:''</font> | <FONT Color=gray>' ''Avviamo l'esecuzione del file Midi:''</font> | ||
| − | + | gst_element_set_state(midi, GST_STATE_PLAYING) | |
| − | + | Repeat | |
| − | + | gst_element_query_duration(midi, GST_FORMAT_TIME, VarPtr(durata)) | |
| − | + | dur = Date(0, 0, 0, 0, 0, 0, durata / 1000000) | |
| − | + | Until dur > 0 | |
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| − | + | tempus = Now | |
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| − | + | Repeat | |
| − | + | dd = DateDiff(tempus, Now, gb.Millisecond) | |
| − | + | Write "\r\e[0mDurata: " & dur & " Pos. \e[31m" & CStr(Date(0, 0, 0, 0, 0, 0, dd)) | |
| − | + | Wait 0.001 | |
| − | + | Until dd > (durata / 1000000) | |
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| − | + | gst_object_unref(midi) | |
| − | + | Print "\nEsecuzione terminata." | |
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'''End''' | '''End''' | ||
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Versione delle 07:56, 22 lug 2020
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"
Usando i plugin "spectrascope" e "autoaudiosink" all'interno della riga della pipeline della funzione gst_parse_launch(), è possibile visualizzare uno spettroscopio attivo durante l'esecuzione di un file Midi.
Mostriamo un esempio pratico:
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
' 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 As Long
Dim dur, tempus As Date
Dim dd As Integer
gst_init(0, 0)
midi = gst_parse_launch("filesrc location=/percorso/del/file.mid ! midiparse ! fluiddec ! tee name=t " &
"! queue ! audioconvert ! spectrascope ! video/x-raw, width=1000, height=500! " &
"videoconvert ! autovideosink ! 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))
dur = Date(0, 0, 0, 0, 0, 0, durata / 1000000)
Until dur > 0
tempus = Now
Repeat
dd = DateDiff(tempus, Now, gb.Millisecond)
Write "\r\e[0mDurata: " & dur & " Pos. \e[31m" & CStr(Date(0, 0, 0, 0, 0, 0, dd))
Wait 0.001
Until dd > (durata / 1000000)
gst_object_unref(midi)
Print "\nEsecuzione terminata."
End
