Visualizzare un oscilloscopio di GStreamer mediante la funzione 'gst parse launch()' durante l'esecuzione di un file Midi: differenze tra le versioni

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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
<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()
  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
  Dim dur, tempus As Date
  Dim dd As Integer
        
        
   gst_init(0, 0)
   gst_init(0, 0)
    
    
   midi = gst_parse_launch("filesrc location=<FONT Color=gray>''/percorso/del/file.mid''</font> ! midiparse ! fluiddec ! tee name=t " &
   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))
     dur = Date(0, 0, 0, 0, 0, 0, durata / 1000000)
     Wait 0.01
   Until dur > 0
   Until durata > -1
 
  tempus = Now
 
   Repeat
   Repeat
     dd = DateDiff(tempus, Now, gb.Millisecond)
     gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos))
     Write "\r\e[0mDurata: " & dur & "      Pos. \e[31m" & CStr(Time(0, 0, 0, dd))
     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 dd > (durata / 1000000)
   Until pos >= durata
    
    
   gst_object_unref(midi)
   gst_object_unref(midi)
   Print "\nEsecuzione terminata."
   Print "\nEsecuzione terminata."
    
    
  '''End'''
  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()
  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
  Dim dur, tempus As Date
  Dim dd As Integer
        
        
   gst_init(0, 0)
   gst_init(0, 0)
    
    
   midi = gst_parse_launch("filesrc location=<FONT Color=gray>''/percorso/del/file.mid''</font> ! midiparse ! fluiddec ! " &
   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))
     dur = Date(0, 0, 0, 0, 0, 0, durata / 1000000)
     Wait 0.01
   Until dur > 0
   Until durata > -1
 
  tempus = Now
 
   Repeat
   Repeat
     dd = DateDiff(tempus, Now, gb.Millisecond)
     gst_element_query_position(midi, GST_FORMAT_TIME, VarPtr(pos))
     Write "\r\e[0mDurata: " & dur & "      Pos. \e[31m" & CStr(Time(0, 0, 0, dd))
     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 dd > (durata / 1000000)
   Until pos >= durata
    
    
   gst_object_unref(midi)
   gst_object_unref(midi)
   Print "\nEsecuzione terminata."
   Print "\nEsecuzione terminata."
    
    
  '''End'''
  End




Versione delle 05:06, 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

Estratto da "https://www.gambas-it.org/wiki/index.php?title=Visualizzare_un_oscilloscopio_di_GStreamer_mediante_la_funzione_%27gst_parse_launch()%27_durante_l%27esecuzione_di_un_file_Midi&oldid=35736"