--- .\org\gstreamer\gst-plugins-bad-1.12.4\gst-libs\gst\gl\meson.build    2017-07-25 10:34:26 +0200
+++ .\gstreamer\gst-plugins-bad-1.12.4\gst-libs\gst\gl\meson.build       2017-12-19 08:30:36 +0100
@@ -549,10 +549,13 @@
       'win32/win32_message_source.c',
       'win32/gstglwindow_win32.c',
       'win32/gstglwindow_win32.c',
+      'win32/gstglcontext_wgl.c',
     ]
     enabled_gl_winsys += 'win32'
     gl_winsys_deps += gdi_dep
     enabled_gl_platforms += 'wgl'
+    glconf.set10('GST_GL_HAVE_WINDOW_WIN32', 1)
+    glconf.set10('GST_GL_HAVE_PLATFORM_WGL', 1)
   endif
 endif