python/gst-trick-mode-looping-2.py

   1 #!/usr/bin/env python3
   2 #
   3 # A simple "trick-mode" looping player.
   4 # Version 2, based on "about-to-finish" handling.
   5 #
   6 # Not working with speed rates other that 1.
   7 #
   8 # Get a test sample with:
   9 # youtube-dl -t http://www.youtube.com/watch?v=yWa-YXiSk2Y
  10
  11 import sys
  12
  13 import gi
  14 gi.require_version('Gst', '1.0')
  15 from gi.repository import Gst
  16 Gst.init(None)
  17
  18 from gi.repository import GLib
  19
  20
  21 class Player:
  22     def __init__(self, uri, rate):
  23         self._uri = uri
  24         self._rate = rate
  25
  26         self._player = Gst.ElementFactory.make("playbin3", "player")
  27         self._player.set_property("uri", uri)
  28         self._player.connect("about-to-finish", self.on_about_to_finish)
  29
  30         bus = self._player.get_bus()
  31         bus.add_signal_watch()
  32         bus.connect('message::error', self.on_error)
  33         bus.connect('message::state-changed', self.on_state_changed)
  34
  35     def run(self):
  36         self._player.set_state(Gst.State.PLAYING)
  37         self.loop = GLib.MainLoop()
  38         self.loop.run()
  39
  40     def quit(self):
  41         self._player.set_state(Gst.State.NULL)
  42         self.loop.quit()
  43
  44     def on_about_to_finish(self, player):
  45         sys.stderr.write(".")
  46         self._player.set_property("uri", self._uri)
  47
  48         # XXX After the first iteration of the loop the playback rate is
  49         # reset to 1. Do I need to re-set the rate here?
  50
  51         # If I uncomment the following line, nothing changes:
  52         #self.set_seek(0)
  53
  54     def on_error(self, bus, msg):
  55         (err, debug) = msg.parse_error()
  56         print("Error: %s" % err, debug)
  57         self.quit()
  58
  59     def on_state_changed(self, bus, msg):
  60         if msg.src != self._player:
  61             return
  62
  63         print('on_state_changed')
  64         old_state, new_state, pending = msg.parse_state_changed()
  65         print("%s -> %s" % (old_state, new_state))
  66         if old_state == Gst.State.READY and new_state == Gst.State.PAUSED:
  67             self.set_rate(self._rate)
  68
  69     def set_rate(self, rate):
  70         self._rate = rate
  71         position = self._player.query_position(Gst.Format.TIME)[1]
  72         self.set_seek(position, True)
  73
  74     def set_seek(self, position, flush=False):
  75         flags = Gst.SeekFlags.SKIP | Gst.SeekFlags.ACCURATE
  76
  77         if flush:
  78             flags |= Gst.SeekFlags.FLUSH
  79
  80         if self._rate >= 0:
  81             seek_event = Gst.Event.new_seek(self._rate,
  82                                             Gst.Format.TIME,
  83                                             flags,
  84                                             Gst.SeekType.SET, position,
  85                                             Gst.SeekType.NONE, 0)
  86         else:
  87             seek_event = Gst.Event.new_seek(self._rate,
  88                                             Gst.Format.TIME,
  89                                             flags,
  90                                             Gst.SeekType.NONE, 0,
  91                                             Gst.SeekType.END, position)
  92
  93         if seek_event:
  94             self._player.send_event(seek_event)
  95             Gst.info("rate set to %s" % self._rate)
  96         else:
  97             Gst.warining("change rate failed")
  98
  99
 100 def main(args):
 101     def usage():
 102         sys.stdout.write("usage: %s <filename> <speedrate>\n" % args[0])
 103
 104     if len(args) != 3:
 105         usage()
 106         sys.exit(1)
 107
 108     uri = Gst.filename_to_uri(args[1])
 109     rate = float(args[2])
 110
 111     player = Player(uri, rate)
 112     player.run()
 113
 114 if __name__ == '__main__':
 115     sys.exit(main(sys.argv))