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

   1 #!/usr/bin/env python
   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 GObject
  19 GObject.threads_init()
  20
  21
  22 class Player:
  23     def __init__(self, uri, rate):
  24         self._uri = uri
  25         self._rate = rate
  26
  27         self._player = Gst.ElementFactory.make("playbin", "player")
  28         self._player.set_property("uri", uri)
  29         self._player.connect("about-to-finish", self.on_about_to_finish)
  30
  31         bus = self._player.get_bus()
  32         bus.add_signal_watch()
  33         bus.connect('message::error', self.on_error)
  34         bus.connect('message::state-changed', self.on_state_changed)
  35
  36     def run(self):
  37         self._player.set_state(Gst.State.PLAYING)
  38         self.loop = GObject.MainLoop()
  39         self.loop.run()
  40
  41     def quit(self):
  42         self._player.set_state(Gst.State.NULL)
  43         self.loop.quit()
  44
  45     def on_about_to_finish(self, player):
  46         sys.stderr.write(".")
  47         self._player.set_property("uri", self._uri)
  48
  49         # XXX After the first iteration of the loop the playback rate is
  50         # reset to 1. Do I need to re-set the rate here?
  51
  52         # If I uncomment the following line, nothing changes:
  53         #self.set_seek(0)
  54
  55     def on_error(self, bus, msg):
  56         (err, debug) = msg.parse_error()
  57         print "Error: %s" % err, debug
  58         self.quit()
  59
  60     def on_state_changed(self, bus, msg):
  61         if msg.src != self._player:
  62             return
  63
  64         print 'on_state_changed'
  65         old_state, new_state, pending = msg.parse_state_changed()
  66         print "%s -> %s" % (old_state, new_state)
  67         if old_state == Gst.State.READY and new_state == Gst.State.PAUSED:
  68             self.set_rate(self._rate)
  69
  70     def set_rate(self, rate):
  71         self._rate = rate
  72         position = self._player.query_position(Gst.Format.TIME)[1]
  73         self.set_seek(position, True)
  74
  75     def set_seek(self, position, flush=False):
  76         flags = Gst.SeekFlags.SKIP | Gst.SeekFlags.ACCURATE
  77
  78         if flush:
  79             flags |= Gst.SeekFlags.FLUSH
  80
  81         if self._rate >= 0:
  82             seek_event = Gst.Event.new_seek(self._rate,
  83                                             Gst.Format.TIME,
  84                                             flags,
  85                                             Gst.SeekType.SET, position,
  86                                             Gst.SeekType.NONE, 0)
  87         else:
  88             seek_event = Gst.Event.new_seek(self._rate,
  89                                             Gst.Format.TIME,
  90                                             flags,
  91                                             Gst.SeekType.NONE, 0,
  92                                             Gst.SeekType.END, position)
  93
  94         if seek_event:
  95             self._player.send_event(seek_event)
  96             Gst.info("rate set to %s" % self._rate)
  97         else:
  98             Gst.warining("change rate failed")
  99
 100
 101 def main(args):
 102     def usage():
 103         sys.stdout.write("usage: %s <filename> <speedrate>\n" % args[0])
 104
 105     if len(args) != 3:
 106         usage()
 107         sys.exit(1)
 108
 109     uri = Gst.filename_to_uri(args[1])
 110     rate = float(args[2])
 111
 112     player = Player(uri, rate)
 113     player.run()
 114
 115 if __name__ == '__main__':
 116     sys.exit(main(sys.argv))