python/gst-decoupled-pipelines.py

   1 #!/usr/bin/env python3
   2
   3 import sys
   4
   5 from math import pi
   6
   7 import gi
   8 gi.require_version('Gst', '1.0')
   9 from gi.repository import Gst
  10 Gst.init(None)
  11
  12 from gi.repository import GLib
  13
  14
  15 PIPELINE_SRC = """
  16 videotestsrc pattern=18 background-color=4294901760 ! intervideosink
  17 """
  18
  19 #PIPELINE_SRC = """
  20 #v4l2src ! video/x-raw,width=320,height=240 ! intervideosink
  21 #"""
  22
  23 PIPELINE_SINK = """
  24 intervideosrc timeout=-1 ! videoconvert ! rotate name=rotate ! videoconvert ! autovideosink
  25 """
  26
  27
  28 class Player:
  29     def __init__(self):
  30         self.loop = GLib.MainLoop()
  31         self.pipeline_src = Gst.parse_launch(PIPELINE_SRC)
  32         self.pipeline_sink = Gst.parse_launch(PIPELINE_SINK)
  33
  34         self.rotate = self.pipeline_sink.get_by_name('rotate')
  35         self.paused = 0
  36         self.angle = 0
  37
  38         bus = self.pipeline_src.get_bus()
  39         bus.add_signal_watch()
  40         bus.connect('message::eos', self.on_eos)
  41         bus.connect('message::error', self.on_error)
  42         bus.connect('message::state-changed', self .on_state_changed)
  43
  44     def run(self):
  45         self.pipeline_src.set_state(Gst.State.PLAYING)
  46         self.pipeline_sink.set_state(Gst.State.PLAYING)
  47         self.loop.run()
  48
  49     def quit(self):
  50         self.pipeline_sink.set_state(Gst.State.NULL)
  51         self.pipeline_src.set_state(Gst.State.NULL)
  52         self.loop.quit()
  53
  54     def on_rotate(self):
  55         self.angle -= pi / 100
  56         self.angle %= 2 * pi
  57         self.rotate.set_property("angle", self.angle)
  58
  59     def on_input(self):
  60         print(self.paused)
  61         if self.paused:
  62             self.pipeline_src.set_state(Gst.State.PLAYING)
  63         else:
  64             self.pipeline_src.set_state(Gst.State.PAUSED)
  65
  66         self.paused ^= 1
  67
  68     def on_eos(self, bus, msg):
  69         self.quit()
  70
  71     def on_error(self, bus, msg):
  72         (err, debug) = msg.parse_error()
  73         print("Error: %s" % err)
  74         self.quit()
  75
  76     def on_state_changed(self, bus, msg):
  77         if msg.src != self.pipeline_src:
  78             return
  79
  80         old_state, new_state, pending = msg.parse_state_changed()
  81         print("%s from %s to %s" % (msg.src.get_name(), old_state, new_state))
  82
  83
  84 def main():
  85     player = Player()
  86
  87     def stdin_cb(source, condition):
  88         source.readline()
  89         player.on_input()
  90         return True
  91
  92     def timeout_cb():
  93         player.on_rotate()
  94         return True
  95
  96     GLib.io_add_watch(sys.stdin, GLib.IO_IN, stdin_cb)
  97     GLib.timeout_add(100, timeout_cb)
  98
  99     print("\nPress Enter to freeze the video\n")
 100     player.run()
 101
 102
 103 if __name__ == '__main__':
 104     sys.exit(main())