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 GObject
  13 GObject.threads_init()
  14
  15
  16 PIPELINE_SRC = """
  17 videotestsrc pattern=18 background-color=4294901760 ! intervideosink
  18 """
  19
  20 #PIPELINE_SRC = """
  21 #v4l2src ! video/x-raw,width=320,height=240 ! intervideosink
  22 #"""
  23
  24 PIPELINE_SINK = """
  25 intervideosrc timeout=-1 ! videoconvert ! rotate name=rotate ! videoconvert ! autovideosink
  26 """
  27
  28
  29 class Player:
  30     def __init__(self):
  31         self.loop = GObject.MainLoop()
  32         self.pipeline_src = Gst.parse_launch(PIPELINE_SRC)
  33         self.pipeline_sink = Gst.parse_launch(PIPELINE_SINK)
  34
  35         self.rotate = self.pipeline_sink.get_by_name('rotate')
  36         self.paused = 0
  37         self.angle = 0
  38
  39         bus = self.pipeline_src.get_bus()
  40         bus.add_signal_watch()
  41         bus.connect('message::eos', self.on_eos)
  42         bus.connect('message::error', self.on_error)
  43         bus.connect('message::state-changed', self .on_state_changed)
  44
  45     def run(self):
  46         self.pipeline_src.set_state(Gst.State.PLAYING)
  47         self.pipeline_sink.set_state(Gst.State.PLAYING)
  48         self.loop.run()
  49
  50     def quit(self):
  51         self.pipeline_sink.set_state(Gst.State.NULL)
  52         self.pipeline_src.set_state(Gst.State.NULL)
  53         self.loop.quit()
  54
  55     def on_rotate(self):
  56         self.angle -= pi / 100
  57         self.angle %= 2 * pi
  58         self.rotate.set_property("angle", self.angle)
  59
  60     def on_input(self):
  61         print(self.paused)
  62         if self.paused:
  63             self.pipeline_src.set_state(Gst.State.PLAYING)
  64         else:
  65             self.pipeline_src.set_state(Gst.State.PAUSED)
  66
  67         self.paused ^= 1
  68
  69     def on_eos(self, bus, msg):
  70         self.quit()
  71
  72     def on_error(self, bus, msg):
  73         (err, debug) = msg.parse_error()
  74         print("Error: %s" % err)
  75         self.quit()
  76
  77     def on_state_changed(self, bus, msg):
  78         if msg.src != self.pipeline_src:
  79             return
  80
  81         old_state, new_state, pending = msg.parse_state_changed()
  82         print("%s from %s to %s" % (msg.src.get_name(), old_state, new_state))
  83
  84
  85 def main():
  86     player = Player()
  87
  88     def stdin_cb(source, condition):
  89         source.readline()
  90         player.on_input()
  91         return True
  92
  93     def timeout_cb():
  94         player.on_rotate()
  95         return True
  96
  97     GObject.io_add_watch(sys.stdin, GObject.IO_IN, stdin_cb)
  98     GObject.timeout_add(100, timeout_cb)
  99
 100     print("\nPress Enter to freeze the video\n")
 101     player.run()
 102
 103
 104 if __name__ == '__main__':
 105     sys.exit(main())