Sugar Almanac GStreamer

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Revision as of 17:10, 2 October 2008 by 146.115.56.126 (talk) (How can I play back video files in my activity?)
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  Sugar Almanac

Where can I get additional resources and sample code on using the camera?


How can I embed video files in my activity?

Sugar, by default, can play back audio (encoded in Vorbis) and video (encoded in Theora) files in ogg containers.

The following file will be helpful for embedding video or audio files into your activity. After the code posting is a code snippet showing how to use this.

import gtk
import pygtk
pygtk.require('2.0')
import sys
import pygst
pygst.require('0.10')
import gst
import gst.interfaces
import gobject
import time
gobject.threads_init()


class Gplay:

	def __init__(self):
		self.window = None
		self.playing = False

		self.player = gst.element_factory_make("playbin", "playbin")
		xis = gst.element_factory_make("xvimagesink", "xvimagesink")
		self.player.set_property("video-sink", xis)
		bus = self.player.get_bus()
		bus.enable_sync_message_emission()
		bus.add_signal_watch()
		self.SYNC_ID = bus.connect('sync-message::element', self._onSyncMessageCb)


	def _onSyncMessageCb(self, bus, message):
		if message.structure is None:
			return True
		if message.structure.get_name() == 'prepare-xwindow-id':
			self.window.set_sink(message.src)
			message.src.set_property('force-aspect-ratio', True)
			return True


	def setFile(self, path):
		uri = "file://" + str( path )
		if (self.player.get_property('uri') == uri):
			self.seek(gst.SECOND*0)
			return

		self.player.set_state(gst.STATE_READY)
		self.player.set_property('uri', uri)
		ext = uri[len(uri)-3:]
		if (ext == "jpg"):
			self.pause()
		else:
			self.play()


	def queryPosition(self):
		#"Returns a (position, duration) tuple"
		try:
			position, format = self.player.query_position(gst.FORMAT_TIME)
		except:
			position = gst.CLOCK_TIME_NONE

		try:
			duration, format = self.player.query_duration(gst.FORMAT_TIME)
		except:
			duration = gst.CLOCK_TIME_NONE

		return (position, duration)


	def seek(self, time):
		event = gst.event_new_seek(1.0, gst.FORMAT_TIME, gst.SEEK_FLAG_FLUSH | gst.SEEK_FLAG_ACCURATE, gst.SEEK_TYPE_SET, time, gst.SEEK_TYPE_NONE, 0)
		res = self.player.send_event(event)
		if res:
			self.player.set_new_stream_time(0L)


	def pause(self):
		self.playing = False
		self.player.set_state(gst.STATE_PAUSED)


	def play(self):
		self.playing = True
		self.player.set_state(gst.STATE_PLAYING)


	def stop(self):
		self.playing = False
		self.player.set_state(gst.STATE_NULL)
		self.nextMovie()


	def get_state(self, timeout=1):
		return self.player.get_state(timeout=timeout)


	def is_playing(self):
		return self.playing


class PlayVideoWindow(gtk.Window):
	def __init__(self):
		gtk.Window.__init__(self)

		self.imagesink = None
		self.unset_flags(gtk.DOUBLE_BUFFERED)
		self.set_flags(gtk.APP_PAINTABLE)


	def set_sink(self, sink):
		if (self.imagesink != None):
			assert self.window.xid
			self.imagesink = None
			del self.imagesink

		self.imagesink = sink
		self.imagesink.set_xwindow_id(self.window.xid)

And here is a code snippet showing how you would use this file to embed media playback in your activity:

		#this is our video playback window
		self.gplay = Gplay( )
		self.gplayWin = PlayVideoWindow( )
		self.gplay.window = self.gplayWin

		self.gplayWin.set_type_hint( gtk.gdk.WINDOW_TYPE_HINT_DIALOG )
		self.gplayWin.set_decorated( False )
		self.gplayWin.set_transient_for( self ) #activity subclass
		self.gplayWin.move( 100, 100 )
		self.gplayWin.resize( 300, 400 )
		self.gplayWin.show_all( )