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 GObject
  28 GObject.threads_init()
  29
  30
  31 class Player:
  32     def __init__(self):
  33         self.loop = GObject.MainLoop()
  34         self.pipeline = Gst.ElementFactory.make("playbin", "player")
  35
  36         files = ["sample_440hz.webm", "sample_880hz.webm"]
  37         self.uris = [Gst.filename_to_uri(f) for f in files]
  38         self.uri_index = 0
  39         self.pipeline.set_property("uri", self.uris[self.uri_index])
  40         self.pipeline.connect("about-to-finish", self.on_about_to_finish)
  41
  42         bus = self.pipeline.get_bus()
  43         bus.add_signal_watch()
  44         bus.connect('message::eos', self.on_eos)
  45         bus.connect('message::error', self.on_error)
  46         bus.connect('message::state-changed', self.on_state_changed)
  47
  48     def on_about_to_finish(self, playbin):
  49         sys.stderr.write(".")
  50         sys.stderr.flush()
  51         playbin.set_property("uri", self.uris[self.uri_index])
  52
  53     def run(self):
  54         self.pipeline.set_state(Gst.State.PLAYING)
  55         self.loop.run()
  56
  57     def quit(self):
  58         self.pipeline.set_state(Gst.State.NULL)
  59         self.loop.quit()
  60
  61     def switch(self):
  62         self.uri_index ^= 1
  63         print("Next: %s" % self.uris[self.uri_index])
  64
  65         # Seek to the end of the stream, this will trigger the about-to-finish
  66         # signal
  67         seek_event = Gst.Event.new_seek(1.0,
  68                                         Gst.Format.TIME,
  69                                         Gst.SeekFlags.FLUSH,
  70                                         Gst.SeekType.END, -1,
  71                                         Gst.SeekType.NONE, 0)
  72
  73         self.pipeline.send_event(seek_event)
  74
  75     def on_eos(self, bus, msg):
  76         self.quit()
  77
  78     def on_error(self, bus, msg):
  79         (err, debug) = msg.parse_error()
  80         print("Error: %s" % err)
  81         print("Error: %s" % debug)
  82         self.quit()
  83
  84     def on_state_changed(self, bus, msg):
  85         if msg.src != self.pipeline:
  86             return
  87
  88         old_state, new_state, pending = msg.parse_state_changed()
  89         print("%s from %s to %s" % (msg.src.get_name(), old_state, new_state))
  90
  91
  92 def main():
  93     player = Player()
  94
  95     def stdin_cb(source, condition):
  96         source.readline()
  97         player.switch()
  98         return True
  99
 100     GObject.io_add_watch(sys.stdin, GObject.IO_IN, stdin_cb)
 101
 102     print("\nPress Enter to switch the source\n")
 103     player.run()
 104
 105
 106 if __name__ == '__main__':
 107     sys.exit(main())