How to write a wxPython video player with Gstreamer

wxPython ships by default with the wx.MediaCtrl for very basic playback of music or videos. As I would like to do more advanced video manipulation, I was curious if I could use Gstreamer directly in wxPython to create my own pipelines. It was surprisingly easy.
For those who don't know Gstreamer, I quote the website (http://www.gstreamer.org):

GStreamer is a library that allows the construction of graphs of media-handling components, ranging from simple playback to complex audio (mixing) and video (non-linear editing) processing. Applications can take advantage of advances in codec and filter technology transparently.

There are python bindings for it, of which the documentation can be found on http://pygstdocs.berlios.de
I would also suggest to read these introductions to gstreamer & python:

I translated the video player example 2.2 of the tutorial from pyGtk to wxPython:
http://pygstdocs.berlios.de/pygst-tutorial/playbin.html

It should be straightforward to use this as a base for implementing your own pipelines. I work on Ubuntu, where I could install everything straight from the standard repositories.

Here is the source code:

#!/usr/bin/env python
#Example 2.2 http://pygstdocs.berlios.de/pygst-tutorial/playbin.html

import sys, os
import wx
import pygst
pygst.require("0.10")
import gst

import gobject
gobject.threads_init()

class WX_Main(wx.App):

def OnInit(self):
window = wx.Frame(None)
window.SetTitle("Video-Player")
window.SetSize((500, 400))
window.Bind(wx.EVT_CLOSE,self.destroy)
vbox = wx.BoxSizer(wx.VERTICAL)
hbox = wx.BoxSizer(wx.HORIZONTAL)
self.entry = wx.TextCtrl(window)
hbox.Add(self.entry, 1, wx.ALL|wx.ALIGN_CENTER_VERTICAL, 4)
self.button = wx.Button(window,label="Start")
hbox.Add(self.button, 0, wx.ALL|wx.ALIGN_CENTER_VERTICAL, 4)
self.button.Bind(wx.EVT_BUTTON, self.start_stop)
vbox.Add(hbox, 0, wx.EXPAND, 0)
self.movie_window = wx.Panel(window)
vbox.Add(self.movie_window,1,wx.ALL|wx.EXPAND,4)
window.SetSizer(vbox)
window.Layout()
window.Show()
self.SetTopWindow(window)

self.player = gst.element_factory_make("playbin", "player")
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)

return True

def start_stop(self, event):
if self.button.GetLabel() == "Start":
filepath = self.entry.GetValue()
if os.path.exists(filepath):
self.button.SetLabel("Stop")
self.player.set_property('uri',"file://" + filepath)
self.player.set_state(gst.STATE_PLAYING)
else:
self.player.set_state(gst.STATE_NULL)
self.button.SetLabel("Start")

def on_message(self, bus, message):
t = message.type
if t == gst.MESSAGE_EOS:
self.player.set_state(gst.STATE_NULL)
self.button.SetLabel("Start")
elif t == gst.MESSAGE_ERROR:
self.player.set_state(gst.STATE_NULL)
self.button.SetLabel("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':
imagesink = message.src
imagesink.set_property('force-aspect-ratio', True)
imagesink.set_xwindow_id(self.movie_window.GetHandle())

def destroy(self,event):
#Stop the player pipeline to prevent a X Window System error
self.player.set_state(gst.STATE_NULL)
event.Skip()

app = WX_Main()
app.MainLoop()

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How to write a wxPython video player with Gstreamer