In my program I use PyGObject/PyGI and GStreamer to show a video in my GUI. The video is shown in a Gtk.DrawingArea and therefore I need to get it's window-handle in the realize-signal-handler. On Linux I get that handle using:
drawing_area.get_property('window').get_xid()
But how do I get the handle on Windows?
I searched on the internet but found only examples for PyGtk using window.handle which does not work using PyGI.
The GStreamer documentation provides an example which uses the GDK_WINDOW_HWND macro to get the handle. This macro uses AFAIK gdk_win32_drawable_get_handle. But how to do it in Python using PyGI?
Update 15-07-28: Added (simplified) code
I'm still not getting video playback to work on Windows.
Problem 1: I cannot get the window handle in _on_video_realize().
Problem 2: The method _on_player_sync_message() is never called.
class MultimediaPlayer:
def __init__(self):
# ... some init stuff ...
self._drawing_area.connect('realize', self._on_video_realize)
self._drawing_area.connect('unrealize', self._on_video_unrealize)
# GStreamer setup
# ---------------
self._player = Gst.ElementFactory.make('playbin', 'MultimediaPlayer')
bus = self._player.get_bus()
bus.add_signal_watch()
bus.connect('message', self._on_player_message)
bus.enable_sync_message_emission()
bus.connect('sync-message::element', self._on_player_sync_message)
def _on_video_realize(self, widget):
print('----------> _on_video_realize')
# The xid must be retrieved first in GUI-thread and before
# playing pipeline.
if sys.platform == "win32":
self._drawing_area.get_property('window').ensure_native()
# -------------------------------------------------------------
# TODO [PROBLEM 1] How to get handle here?
# self._drawing_area.GetHandle() does not exist!
# -------------------------------------------------------------
else:
self._wnd_hnd = (self._drawing_area.get_property('window')
.get_xid())
def _on_video_unrealize(self, widget):
self._player.set_state(Gst.State.NULL)
def _on_player_message(self, bus, message):
# ... handle some messages here ...
def _on_player_sync_message(self, bus, message):
# ---------------------------------------------------------------------
# TODO [PROBLEM 2] This method is never called on Windows after opening
# a video_file! But on Linux it is!
# ---------------------------------------------------------------------
print('----------> _on_player_sync_message')
if message.get_structure() is None:
return True
if message.get_structure().get_name() == "prepare-window-handle":
imagesink = message.src
imagesink.set_property("force-aspect-ratio", True)
imagesink.set_window_handle(self._wnd_hnd)
def play(self):
self._player.set_state(Gst.State.PLAYING)
def stop(self):
self._player.set_state(Gst.State.NULL)
def set_file(self, file):
# ...
self._player.set_property('uri', "file:///" + file)
I finally got it. To address the "window handle"-issue I use the workaround/hack by Marwin Schmitt (see here):
def _on_video_realize(self, widget):
# The window handle must be retrieved first in GUI-thread and before
# playing pipeline.
video_window = self._drawing_area.get_property('window')
if sys.platform == "win32":
if not video_window.ensure_native():
print("Error - video playback requires a native window")
ctypes.pythonapi.PyCapsule_GetPointer.restype = ctypes.c_void_p
ctypes.pythonapi.PyCapsule_GetPointer.argtypes = [ctypes.py_object]
drawingarea_gpointer = ctypes.pythonapi.PyCapsule_GetPointer(video_window.__gpointer__, None)
gdkdll = ctypes.CDLL ("libgdk-3-0.dll")
self._video_window_handle = gdkdll.gdk_win32_window_get_handle(drawingarea_gpointer)
else:
self._video_window_handle = video_window.get_xid()
But there was also the problem, that the "sync-message"-handler was never called. I found out that not all video sinks support embedded video, see here. For example the d3dvideosink does support embedded video, but I was running Windows in a virtual machine and even though 3D hardware acceleration was activated it probably didn't work. Running the same code on a non-virtualized Windows leads to a callback to the "sync-message"-handler where the previously fetched window-handle can be set:
def _on_player_sync_message(self, bus, message):
if message.get_structure() is None:
return
if not GstVideo.is_video_overlay_prepare_window_handle_message(message):
return
imagesink = message.src
imagesink.set_property("force-aspect-ratio", True)
imagesink.set_window_handle(self._video_window_handle)
Playback on Windows works fine now.