/home/nand

Since I started hacking with python a few months ago, I never stopped being amazed by its power.

Wanna display you webcam video on a very simple GTK+ app? Less than one hundred lines, thanks to pygst (gstreamer) and pygtk!

 #!/usr/bin/env python

import sys, os
import pygtk, gtk, gobject
import pygst
pygst.require("0.10")
import gst

class GTK_Main:

	def __init__(self):
		window = gtk.Window(gtk.WINDOW_TOPLEVEL)
		window.set_title("Webcam-Viewer")
		window.set_default_size(500, 400)
		window.connect("destroy", gtk.main_quit, "WM destroy")
		vbox = gtk.VBox()
		window.add(vbox)
		self.movie_window = gtk.DrawingArea()
		vbox.add(self.movie_window)
		hbox = gtk.HBox()
		vbox.pack_start(hbox, False)

		hbox.set_border_width(10)
		hbox.pack_start(gtk.Label())
		self.button = gtk.Button("Start")
		self.button.connect("clicked", self.start_stop)
		hbox.pack_start(self.button, False)
		self.button2 = gtk.Button("Quit")
		self.button2.connect("clicked", self.exit)
		hbox.pack_start(self.button2, False)
		hbox.add(gtk.Label())

		window.show_all()

		# Set up the gstreamer pipepile
		self.player = gst.parse_launch ("v4l2src  !  autovideosink")

		bus = self.player.get_bus()
		bus.add_signal_watch()
		bus.enable_sync_message_emission()
		bus.connect('message', self.on_message)
		bus.connect('sync-message::element', self.on_sync_message)

	def start_stop(self, w):
		if self.button.get_label() == "Start":
			self.button.set_label("Stop")
			self.player.set_state(gst.STATE_PLAYING)
		else:
			self.player.set_state(gst.STATE_NULL)
			self.button.set_label("Start")

	def exit(self, widget, data=None):
		gtk.main_quit()

	def on_message(self, bus, message):
		t = message.type
		if t == gst.MESSAGE_EOS:
			self.player.set_state(gst.STATE_NULL)
			self.button.set_label("Start")
		elif t == gst.MESSAGE_ERROR:
			err, debug = message.parse_error()
			print "Error: %s" % err, debug
			self.player.set_state(gst.STATE_NULL)
			self.button.set_label("Start")

	def on_sync_message(self, bus, message):
		if message.structure is None:
			return
		message_name = message.structure.get_name()
		if message_name == 'prepare-xwindow-id':
			# Assign the viewport
			imagesink = message.src
			imagesink.set_property('force-aspect-ratio', True)
			imagesink.set_xwindow_id(self.movie_window.window.xid)

GTK_Main()
gtk.gdk.threads_init()
gtk.main()

And here you are! I could have reduced even more the code by using Glade to design and dynamically load the UI.

(there is supposed to be an image instead of the blackbox. Anyone know how to screenshot a Xv window?)