python/gst-playbin-switch.py

   1 #!/usr/bin/env python3
   2 #
   3 # gst-playbin-switch - an example of switching file inputs with playbin
   4 #
   5 # Copyright (C) 2016  Antonio Ospite <ao2@ao2.it>
   6 #
   7 # This program is free software: you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation, either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19
  20 import sys
  21
  22 import gi
  23 gi.require_version('Gst', '1.0')
  24 from gi.repository import Gst
  25 Gst.init(None)
  26
  27 from gi.repository import GLib
  28
  29
  30 class Player:
  31     def __init__(self):
  32         self.loop = GLib.MainLoop()
  33         self.pipeline = Gst.ElementFactory.make("playbin3", "player")
  34
  35         files = ["sample_440hz.webm", "sample_880hz.webm"]
  36         self.uris = [Gst.filename_to_uri(f) for f in files]
  37         self.uri_index = 0
  38         self.pipeline.set_property("uri", self.uris[self.uri_index])
  39         self.pipeline.connect("about-to-finish", self.on_about_to_finish)
  40
  41         bus = self.pipeline.get_bus()
  42         bus.add_signal_watch()
  43         bus.connect('message::eos', self.on_eos)
  44         bus.connect('message::error', self.on_error)
  45         bus.connect('message::state-changed', self.on_state_changed)
  46
  47     def on_about_to_finish(self, playbin):
  48         sys.stderr.write(".")
  49         sys.stderr.flush()
  50         playbin.set_property("uri", self.uris[self.uri_index])
  51
  52     def run(self):
  53         self.pipeline.set_state(Gst.State.PLAYING)
  54         self.loop.run()
  55
  56     def quit(self):
  57         self.pipeline.set_state(Gst.State.NULL)
  58         self.loop.quit()
  59
  60     def on_switch(self):
  61         self.uri_index ^= 1
  62         print("Next: %s" % self.uris[self.uri_index])
  63
  64         # Seek to the end of the stream, this will trigger the about-to-finish
  65         # signal
  66         seek_event = Gst.Event.new_seek(1.0,
  67                                         Gst.Format.TIME,
  68                                         Gst.SeekFlags.FLUSH,
  69                                         Gst.SeekType.END, -1,
  70                                         Gst.SeekType.NONE, 0)
  71
  72         self.pipeline.send_event(seek_event)
  73
  74     def on_eos(self, bus, msg):
  75         self.quit()
  76
  77     def on_error(self, bus, msg):
  78         (err, debug) = msg.parse_error()
  79         print("Error: %s" % err)
  80         print("Error: %s" % debug)
  81         self.quit()
  82
  83     def on_state_changed(self, bus, msg):
  84         if msg.src != self.pipeline:
  85             return
  86
  87         old_state, new_state, pending = msg.parse_state_changed()
  88         print("%s from %s to %s" % (msg.src.get_name(), old_state, new_state))
  89
  90
  91 def main():
  92     player = Player()
  93
  94     def stdin_cb(source, condition):
  95         source.readline()
  96         player.on_switch()
  97         return True
  98
  99     GLib.io_add_watch(sys.stdin, GLib.IO_IN, stdin_cb)
 100
 101     print("\nPress Enter to switch the source\n")
 102     player.run()
 103
 104
 105 if __name__ == '__main__':
 106     sys.exit(main())