new qt5 qml GL video sink

Very much in the same spirit as the Gtk GL sink

Two things are provided
1. A QQuickItem subclass that renders out RGBA filled GstGLMemory
   buffers that is instantiated from qml.
2. A sink element that will push buffers into (1)

To use
1. Declare the GstGLVideoItem in qml with an appropriate
   objectName property set.
2. Get the aforementioned GstGLVideoItem from qml using something like

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

QObject *rootObject = engine.rootObjects().first();
QQuickItem *videoItem = rootObject->findChild<QQuickItem *> ("videoItem");

3. Set the videoItem on the sink

https://bugzilla.gnome.org/show_bug.cgi?id=752185

10 files changed, 1448 insertions, 0 deletions

diff --git a/ext/Makefile.am b/ext/Makefile.am
index 66dccd6b6..33ddba7ea 100644
--- a/ext/Makefile.am
+++ b/ext/Makefile.am
@@ -94,6 +94,12 @@ else
 GTK3_DIR=
 endif
 
+if USE_QT
+QT_DIR=qt
+else
+QT_DIR=
+endif
+
 if USE_RESINDVD
  RESINDVD_DIR = resindvd
 else
@@ -443,6 +449,7 @@ SUBDIRS=\
 	$(RESINDVD_DIR) \
 	$(GL_DIR) \
 	$(GTK3_DIR) \
+	$(QT_DIR) \
 	$(FAAC_DIR) \
 	$(FAAD_DIR) \
 	$(FLITE_DIR) \
@@ -524,6 +531,7 @@ DIST_SUBDIRS = \
 	dts \
 	gl \
 	gtk \
+	qt \
 	modplug \
 	mimic \
 	mpeg2enc \
diff --git a/ext/qt/.gitignore b/ext/qt/.gitignore
new file mode 100644
index 000000000..f830c38fc
--- /dev/null
+++ b/ext/qt/.gitignore
@@ -0,0 +1 @@
+moc_*.cc
diff --git a/ext/qt/Makefile.am b/ext/qt/Makefile.am
new file mode 100644
index 000000000..5dc38dc08
--- /dev/null
+++ b/ext/qt/Makefile.am
@@ -0,0 +1,55 @@
+# preamble
+NULL =
+
+moc_headers = \
+	qtitem.h \
+	gstqsgtexture.h \
+	$(NULL)
+
+moc_generated = \
+	moc_qtitem.cc \
+	moc_gstqsgtexture.cc \
+	$(NULL)
+
+#anything generated by the Qt tools...
+BUILT_SOURCES = $(moc_generated)
+CLEANFILES = $(moc_generated)
+
+sources = \
+	gstqsgtexture.cc \
+	qtitem.cc \
+	gstqtsink.cc \
+	gstqtsink.h \
+	gstplugin.cc \
+	$(moc_headers) \
+	$(moc_generated) \
+	$(NULL)
+
+libqtsink_la_CXXFLAGS = \
+	-I$(top_srcdir)/gst-libs \
+	-I$(top_builddir)/gst-libs \
+	$(GST_CXXFLAGS) \
+	$(GST_BASE_CFLAGS) \
+	$(GST_PLUGINS_BASE_CFLAGS) \
+	$(QT_CFLAGS)
+libqtsink_la_LIBADD = \
+	$(GST_BASE_LIBS) \
+	$(GST_PLUGINS_BASE_LIBS) \
+	$(QT_LIBS) \
+	$(top_builddir)/gst-libs/gst/gl/libgstgl-$(GST_API_VERSION).la \
+	-lgstvideo-$(GST_API_VERSION)
+
+libqtsink_la_SOURCES = $(sources)
+libqtsink_la_LDFLAGS = $(GST_PLUGIN_LDFLAGS)
+libqtsink_la_LIBTOOLFLAGS = $(GST_PLUGIN_LIBTOOLFLAGS)
+
+plugin_LTLIBRARIES = libqtsink.la
+
+$(moc_generated): moc_%.cc: %.h
+	@@MOC@ -o$@ $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(MOC_CPPFLAGS) $<
+
+ui-%.h: %.ui
+	@@UIC@ -o $@ $<
+
+qrc-%.cc: %.qrc
+	@@RCC@ -o $@ $<
diff --git a/ext/qt/gstplugin.cc b/ext/qt/gstplugin.cc
new file mode 100644
index 000000000..70b6310f0
--- /dev/null
+++ b/ext/qt/gstplugin.cc
@@ -0,0 +1,46 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstqtsink.h"
+#include <QQmlApplicationEngine>
+
+static gboolean
+plugin_init (GstPlugin * plugin)
+{
+  if (!gst_element_register (plugin, "qmlglsink",
+          GST_RANK_NONE, GST_TYPE_QT_SINK)) {
+    return FALSE;
+  }
+  /* this means the plugin must be loaded before the qml engine is loaded */
+  qmlRegisterType<QtGLVideoItem> ("org.freedesktop.gstreamer.GLVideoItem", 1, 0, "GstGLVideoItem");
+
+  return TRUE;
+}
+
+GST_PLUGIN_DEFINE (GST_VERSION_MAJOR,
+    GST_VERSION_MINOR,
+    qt,
+    "Qt sink",
+    plugin_init, PACKAGE_VERSION, GST_LICENSE, GST_PACKAGE_NAME,
+    GST_PACKAGE_ORIGIN)
diff --git a/ext/qt/gstqsgtexture.cc b/ext/qt/gstqsgtexture.cc
new file mode 100644
index 000000000..1e5203832
--- /dev/null
+++ b/ext/qt/gstqsgtexture.cc
@@ -0,0 +1,142 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+
+#include <gst/video/video.h>
+#include <gst/gl/gl.h>
+#include "gstqsgtexture.h"
+
+#define GST_CAT_DEFAULT gst_qsg_texture_debug
+GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
+
+GstQSGTexture::GstQSGTexture ()
+{
+  static volatile gsize _debug;
+
+  initializeOpenGLFunctions();
+
+  if (g_once_init_enter (&_debug)) {
+    GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "qtqsgtexture", 0,
+        "Qt Scenegraph Texture");
+    g_once_init_leave (&_debug, 1);
+  }
+
+  gst_video_info_init (&this->v_info);
+  this->buffer_ = NULL;
+}
+
+GstQSGTexture::~GstQSGTexture ()
+{
+  gst_buffer_replace (&this->buffer_, NULL);
+}
+
+/* only called from the streaming thread with scene graph thread blocked */
+void
+GstQSGTexture::setCaps (GstCaps * caps)
+{
+  GST_LOG ("%p setCaps %" GST_PTR_FORMAT, this, caps);
+
+  gst_video_info_from_caps (&this->v_info, caps);
+}
+
+/* only called from the streaming thread with scene graph thread blocked */
+void
+GstQSGTexture::setBuffer (GstBuffer * buffer)
+{
+  GST_LOG ("%p setBuffer %" GST_PTR_FORMAT, this, buffer);
+  /* FIXME: update more state here */
+  gst_buffer_replace (&this->buffer_, buffer);
+}
+
+/* only called from qt's scene graph render thread */
+void
+GstQSGTexture::bind ()
+{
+  guint tex_id;
+
+  if (!this->buffer_)
+    return;
+  if (GST_VIDEO_INFO_FORMAT (&this->v_info) == GST_VIDEO_FORMAT_UNKNOWN)
+    return;
+
+  /* FIXME: should really lock the memory to prevent write access */
+  if (!gst_video_frame_map (&this->v_frame, &this->v_info, this->buffer_,
+        (GstMapFlags) (GST_MAP_READ | GST_MAP_GL))) {
+    g_assert_not_reached ();
+    return;
+  }
+
+  tex_id = *(guint *) this->v_frame.data[0];
+  GST_LOG ("%p binding Qt texture %u", this, tex_id);
+
+  glBindTexture (GL_TEXTURE_2D, tex_id);
+
+  gst_video_frame_unmap (&this->v_frame);
+}
+
+/* can be called from any thread */
+int
+GstQSGTexture::textureId () const
+{
+  int tex_id = 0;
+
+  if (this->buffer_) {
+    GstMemory *mem = gst_buffer_peek_memory (this->buffer_, 0);
+
+    tex_id = ((GstGLMemory *) mem)->tex_id;
+  }
+
+  GST_LOG ("%p get texture id %u", this, tex_id);
+
+  return tex_id;
+}
+
+/* can be called from any thread */
+QSize
+GstQSGTexture::textureSize () const
+{
+  if (GST_VIDEO_INFO_FORMAT (&this->v_info) == GST_VIDEO_FORMAT_UNKNOWN)
+    return QSize (0, 0);
+
+  GST_TRACE ("%p get texture size %ux%u", this, this->v_info.width,
+      this->v_info.height);
+
+  return QSize (this->v_info.width, this->v_info.height);
+}
+
+/* can be called from any thread */
+bool
+GstQSGTexture::hasAlphaChannel () const
+{
+  /* FIXME: support RGB textures */
+  return true;
+}
+
+/* can be called from any thread */
+bool
+GstQSGTexture::hasMipmaps () const
+{
+  return false;
+}
diff --git a/ext/qt/gstqsgtexture.h b/ext/qt/gstqsgtexture.h
new file mode 100644
index 000000000..93fb60d06
--- /dev/null
+++ b/ext/qt/gstqsgtexture.h
@@ -0,0 +1,52 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __GST_QSG_TEXTURE_H__
+#define __GST_QSG_TEXTURE_H__
+
+#include <gst/gst.h>
+#include <QSGTexture>
+#include <QOpenGLFunctions>
+#include <gst/video/video.h>
+
+class GstQSGTexture : public QSGTexture, protected QOpenGLFunctions
+{
+    Q_OBJECT
+public:
+    GstQSGTexture ();
+    ~GstQSGTexture ();
+
+    void setCaps (GstCaps * caps);
+    void setBuffer (GstBuffer * buffer);
+
+    /* QSGTexture */
+    void bind ();
+    int textureId () const;
+    QSize textureSize () const;
+    bool hasAlphaChannel () const;
+    bool hasMipmaps () const;
+
+private:
+    GstBuffer * buffer_;
+    GstVideoInfo v_info;
+    GstVideoFrame v_frame;
+};
+
+#endif /* __GST_QSG_TEXTURE_H__ */
diff --git a/ext/qt/gstqtsink.cc b/ext/qt/gstqtsink.cc
new file mode 100644
index 000000000..40e66d8d7
--- /dev/null
+++ b/ext/qt/gstqtsink.cc
@@ -0,0 +1,500 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+/**
+ * SECTION:gstqtsink
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "gstqtsink.h"
+#include <QGuiApplication>
+
+#define GST_CAT_DEFAULT gst_debug_qt_gl_sink
+GST_DEBUG_CATEGORY (GST_CAT_DEFAULT);
+
+static void gst_qt_sink_finalize (GObject * object);
+static void gst_qt_sink_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * param_spec);
+static void gst_qt_sink_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * param_spec);
+
+static gboolean gst_qt_sink_stop (GstBaseSink * bsink);
+
+static gboolean gst_qt_sink_query (GstBaseSink * bsink, GstQuery * query);
+
+static GstStateChangeReturn
+gst_qt_sink_change_state (GstElement * element, GstStateChange transition);
+
+static void gst_qt_sink_get_times (GstBaseSink * bsink, GstBuffer * buf,
+    GstClockTime * start, GstClockTime * end);
+static gboolean gst_qt_sink_set_caps (GstBaseSink * bsink, GstCaps * caps);
+static GstFlowReturn gst_qt_sink_show_frame (GstVideoSink * bsink,
+    GstBuffer * buf);
+static gboolean gst_qt_sink_propose_allocation (GstBaseSink * bsink,
+    GstQuery * query);
+
+static GstStaticPadTemplate gst_qt_sink_template =
+GST_STATIC_PAD_TEMPLATE ("sink",
+    GST_PAD_SINK,
+    GST_PAD_ALWAYS,
+    GST_STATIC_CAPS (GST_VIDEO_CAPS_MAKE_WITH_FEATURES
+        (GST_CAPS_FEATURE_MEMORY_GL_MEMORY, "RGBA")));
+
+#define DEFAULT_FORCE_ASPECT_RATIO  TRUE
+#define DEFAULT_PAR_N               0
+#define DEFAULT_PAR_D               1
+
+enum
+{
+  ARG_0,
+  PROP_WIDGET,
+  PROP_FORCE_ASPECT_RATIO,
+  PROP_PIXEL_ASPECT_RATIO,
+};
+
+enum
+{
+  SIGNAL_0,
+  LAST_SIGNAL
+};
+
+#define gst_qt_sink_parent_class parent_class
+G_DEFINE_TYPE_WITH_CODE (GstQtSink, gst_qt_sink,
+    GST_TYPE_VIDEO_SINK, GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT,
+        "qtsink", 0, "Qt Video Sink"));
+
+static void
+gst_qt_sink_class_init (GstQtSinkClass * klass)
+{
+  GObjectClass *gobject_class;
+  GstElementClass *gstelement_class;
+  GstBaseSinkClass *gstbasesink_class;
+  GstVideoSinkClass *gstvideosink_class;
+
+  gobject_class = (GObjectClass *) klass;
+  gstelement_class = (GstElementClass *) klass;
+  gstbasesink_class = (GstBaseSinkClass *) klass;
+  gstvideosink_class = (GstVideoSinkClass *) klass;
+
+  gobject_class->set_property = gst_qt_sink_set_property;
+  gobject_class->get_property = gst_qt_sink_get_property;
+
+  gst_element_class_set_metadata (gstelement_class, "Qt Video Sink",
+      "Sink/Video", "A video sink the renders to a QQuickItem",
+      "Matthew Waters <matthew@centricular.com>");
+
+  g_object_class_install_property (gobject_class, PROP_WIDGET,
+      g_param_spec_pointer ("widget", "QQuickItem",
+          "The QQuickItem to place in the object heirachy",
+          (GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
+
+  g_object_class_install_property (gobject_class, PROP_FORCE_ASPECT_RATIO,
+      g_param_spec_boolean ("force-aspect-ratio",
+          "Force aspect ratio",
+          "When enabled, scaling will respect original aspect ratio",
+          DEFAULT_FORCE_ASPECT_RATIO,
+          (GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
+
+  g_object_class_install_property (gobject_class, PROP_PIXEL_ASPECT_RATIO,
+      gst_param_spec_fraction ("pixel-aspect-ratio", "Pixel Aspect Ratio",
+          "The pixel aspect ratio of the device", DEFAULT_PAR_N, DEFAULT_PAR_D,
+          G_MAXINT, 1, 1, 1,
+          (GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
+
+  gst_element_class_add_pad_template (gstelement_class,
+      gst_static_pad_template_get (&gst_qt_sink_template));
+
+  gobject_class->finalize = gst_qt_sink_finalize;
+
+  gstelement_class->change_state = gst_qt_sink_change_state;
+  gstbasesink_class->query = gst_qt_sink_query;
+  gstbasesink_class->set_caps = gst_qt_sink_set_caps;
+  gstbasesink_class->get_times = gst_qt_sink_get_times;
+  gstbasesink_class->propose_allocation = gst_qt_sink_propose_allocation;
+  gstbasesink_class->stop = gst_qt_sink_stop;
+
+  gstvideosink_class->show_frame = gst_qt_sink_show_frame;
+}
+
+static void
+gst_qt_sink_init (GstQtSink * qt_sink)
+{
+}
+
+static void
+gst_qt_sink_set_property (GObject * object, guint prop_id,
+    const GValue * value, GParamSpec * pspec)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (object);
+
+  switch (prop_id) {
+    case PROP_WIDGET:
+      qt_sink->widget = static_cast<QtGLVideoItem *> (g_value_get_pointer (value));
+      break;
+    case PROP_FORCE_ASPECT_RATIO:
+      g_return_if_fail (qt_sink->widget);
+      qt_sink->widget->setForceAspectRatio (g_value_get_boolean (value));
+      break;
+    case PROP_PIXEL_ASPECT_RATIO:
+      g_return_if_fail (qt_sink->widget);
+      qt_sink->widget->setDAR (gst_value_get_fraction_numerator (value),
+          gst_value_get_fraction_denominator (value));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static void
+_reset (GstQtSink * qt_sink)
+{
+  if (qt_sink->display) {
+    gst_object_unref (qt_sink->display);
+    qt_sink->display = NULL;
+  }
+
+  if (qt_sink->context) {
+    gst_object_unref (qt_sink->context);
+    qt_sink->context = NULL;
+  }
+
+  if (qt_sink->qt_context) {
+    gst_object_unref (qt_sink->qt_context);
+    qt_sink->qt_context = NULL;
+  }
+}
+
+static void
+gst_qt_sink_finalize (GObject * object)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (object);
+
+  _reset (qt_sink);
+
+  G_OBJECT_CLASS (parent_class)->finalize (object);
+}
+
+static void
+gst_qt_sink_get_property (GObject * object, guint prop_id,
+    GValue * value, GParamSpec * pspec)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (object);
+
+  switch (prop_id) {
+    case PROP_WIDGET:
+      g_value_set_pointer (value, qt_sink->widget);
+      break;
+    case PROP_FORCE_ASPECT_RATIO:
+      if (qt_sink->widget)
+        g_value_set_boolean (value, qt_sink->widget->getForceAspectRatio ());
+      else
+        g_value_set_boolean (value, DEFAULT_FORCE_ASPECT_RATIO);
+      break;
+    case PROP_PIXEL_ASPECT_RATIO:
+      if (qt_sink->widget) {
+        gint num, den;
+        qt_sink->widget->getDAR (&num, &den);
+        gst_value_set_fraction (value, num, den);
+      } else {
+        gst_value_set_fraction (value, DEFAULT_PAR_N, DEFAULT_PAR_D);
+      }
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+      break;
+  }
+}
+
+static gboolean
+gst_qt_sink_query (GstBaseSink * bsink, GstQuery * query)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (bsink);
+  gboolean res = FALSE;
+
+  switch (GST_QUERY_TYPE (query)) {
+    case GST_QUERY_CONTEXT:
+    {
+      const gchar *context_type;
+      GstContext *context, *old_context;
+      gboolean ret;
+
+      ret = gst_gl_handle_context_query ((GstElement *) qt_sink, query,
+          &qt_sink->display, &qt_sink->qt_context);
+
+      if (qt_sink->display)
+        gst_gl_display_filter_gl_api (qt_sink->display, gst_gl_context_get_gl_api (qt_sink->qt_context));
+
+      gst_query_parse_context_type (query, &context_type);
+
+      if (g_strcmp0 (context_type, "gst.gl.local_context") == 0) {
+        GstStructure *s;
+
+        gst_query_parse_context (query, &old_context);
+
+        if (old_context)
+          context = gst_context_copy (old_context);
+        else
+          context = gst_context_new ("gst.gl.local_context", FALSE);
+
+        s = gst_context_writable_structure (context);
+        gst_structure_set (s, "context", GST_GL_TYPE_CONTEXT, qt_sink->context,
+            NULL);
+        gst_query_set_context (query, context);
+        gst_context_unref (context);
+
+        ret = qt_sink->context != NULL;
+      }
+      GST_LOG_OBJECT (qt_sink, "context query of type %s %i", context_type,
+          ret);
+
+      if (ret)
+        return ret;
+    }
+    default:
+      res = GST_BASE_SINK_CLASS (parent_class)->query (bsink, query);
+      break;
+  }
+
+  return res;
+}
+
+static gboolean
+gst_qt_sink_stop (GstBaseSink * bsink)
+{
+  return TRUE;
+}
+
+static GstStateChangeReturn
+gst_qt_sink_change_state (GstElement * element, GstStateChange transition)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (element);
+  GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
+  QGuiApplication *app;
+
+  GST_DEBUG ("changing state: %s => %s",
+      gst_element_state_get_name (GST_STATE_TRANSITION_CURRENT (transition)),
+      gst_element_state_get_name (GST_STATE_TRANSITION_NEXT (transition)));
+
+  switch (transition) {
+    case GST_STATE_CHANGE_NULL_TO_READY:
+      app = dynamic_cast<QGuiApplication *> (QCoreApplication::instance ());
+      if (!app) {
+        GST_ELEMENT_ERROR (element, RESOURCE, NOT_FOUND,
+            ("%s", "Failed to connect to Qt"),
+            ("%s", "Could not retreive QGuiApplication instance"));
+        return GST_STATE_CHANGE_FAILURE;
+      }
+
+      if (!qt_sink->widget) {
+        GST_ELEMENT_ERROR (element, RESOURCE, NOT_FOUND,
+            ("%s", "Required property \'widget\' not set"),
+            (NULL));
+        return GST_STATE_CHANGE_FAILURE;
+      }
+
+      if (!qt_item_init_winsys (qt_sink->widget)) {
+        GST_ELEMENT_ERROR (element, RESOURCE, NOT_FOUND,
+            ("%s", "Could not initialize window system"),
+            (NULL));
+        return GST_STATE_CHANGE_FAILURE;
+      }
+
+      qt_sink->display = qt_item_get_display (qt_sink->widget);
+      qt_sink->context = qt_item_get_context (qt_sink->widget);
+      qt_sink->qt_context = qt_item_get_qt_context (qt_sink->widget);
+
+      if (!qt_sink->display || !qt_sink->context || !qt_sink->qt_context) {
+        GST_ELEMENT_ERROR (element, RESOURCE, NOT_FOUND,
+            ("%s", "Could not retreive window system OpenGL configuration"),
+            (NULL));
+        return GST_STATE_CHANGE_FAILURE;
+      }
+      break;
+    case GST_STATE_CHANGE_READY_TO_PAUSED:
+      break;
+    case GST_STATE_CHANGE_PAUSED_TO_PLAYING:
+      break;
+    default:
+      break;
+  }
+
+  ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
+  if (ret == GST_STATE_CHANGE_FAILURE)
+    return ret;
+
+  switch (transition) {
+    case GST_STATE_CHANGE_PLAYING_TO_PAUSED:
+      break;
+    case GST_STATE_CHANGE_PAUSED_TO_READY:
+      qt_item_set_buffer (qt_sink->widget, NULL);
+      break;
+    case GST_STATE_CHANGE_READY_TO_NULL:
+      break;
+    default:
+      break;
+  }
+
+  return ret;
+}
+
+static void
+gst_qt_sink_get_times (GstBaseSink * bsink, GstBuffer * buf,
+    GstClockTime * start, GstClockTime * end)
+{
+  GstQtSink *qt_sink;
+
+  qt_sink = GST_QT_SINK (bsink);
+
+  if (GST_BUFFER_TIMESTAMP_IS_VALID (buf)) {
+    *start = GST_BUFFER_TIMESTAMP (buf);
+    if (GST_BUFFER_DURATION_IS_VALID (buf))
+      *end = *start + GST_BUFFER_DURATION (buf);
+    else {
+      if (GST_VIDEO_INFO_FPS_N (&qt_sink->v_info) > 0) {
+        *end = *start +
+            gst_util_uint64_scale_int (GST_SECOND,
+            GST_VIDEO_INFO_FPS_D (&qt_sink->v_info),
+            GST_VIDEO_INFO_FPS_N (&qt_sink->v_info));
+      }
+    }
+  }
+}
+
+gboolean
+gst_qt_sink_set_caps (GstBaseSink * bsink, GstCaps * caps)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (bsink);
+
+  GST_DEBUG ("set caps with %" GST_PTR_FORMAT, caps);
+
+  if (!gst_video_info_from_caps (&qt_sink->v_info, caps))
+    return FALSE;
+
+  if (!qt_item_set_caps (qt_sink->widget, caps))
+    return FALSE;
+
+  return TRUE;
+}
+
+static GstFlowReturn
+gst_qt_sink_show_frame (GstVideoSink * vsink, GstBuffer * buf)
+{
+  GstQtSink *qt_sink;
+
+  GST_TRACE ("rendering buffer:%p", buf);
+
+  qt_sink = GST_QT_SINK (vsink);
+
+  qt_item_set_buffer (qt_sink->widget, buf);
+
+  return GST_FLOW_OK;
+}
+
+static gboolean
+gst_qt_sink_propose_allocation (GstBaseSink * bsink, GstQuery * query)
+{
+  GstQtSink *qt_sink = GST_QT_SINK (bsink);
+  GstBufferPool *pool;
+  GstStructure *config;
+  GstCaps *caps;
+  guint size;
+  gboolean need_pool;
+
+  if (!qt_sink->display || !qt_sink->context)
+    return FALSE;
+
+  gst_query_parse_allocation (query, &caps, &need_pool);
+
+  if (caps == NULL)
+    goto no_caps;
+
+  if ((pool = qt_sink->pool))
+    gst_object_ref (pool);
+
+  if (pool != NULL) {
+    GstCaps *pcaps;
+
+    /* we had a pool, check caps */
+    GST_DEBUG_OBJECT (qt_sink, "check existing pool caps");
+    config = gst_buffer_pool_get_config (pool);
+    gst_buffer_pool_config_get_params (config, &pcaps, &size, NULL, NULL);
+
+    if (!gst_caps_is_equal (caps, pcaps)) {
+      GST_DEBUG_OBJECT (qt_sink, "pool has different caps");
+      /* different caps, we can't use this pool */
+      gst_object_unref (pool);
+      pool = NULL;
+    }
+    gst_structure_free (config);
+  }
+
+  if (pool == NULL && need_pool) {
+    GstVideoInfo info;
+
+    if (!gst_video_info_from_caps (&info, caps))
+      goto invalid_caps;
+
+    GST_DEBUG_OBJECT (qt_sink, "create new pool");
+    pool = gst_gl_buffer_pool_new (qt_sink->context);
+
+    /* the normal size of a frame */
+    size = info.size;
+
+    config = gst_buffer_pool_get_config (pool);
+    gst_buffer_pool_config_set_params (config, caps, size, 0, 0);
+    if (!gst_buffer_pool_set_config (pool, config))
+      goto config_failed;
+  }
+  /* we need at least 2 buffer because we hold on to the last one */
+  if (pool) {
+    gst_query_add_allocation_pool (query, pool, size, 2, 0);
+    gst_object_unref (pool);
+  }
+
+  /* we also support various metadata */
+  gst_query_add_allocation_meta (query, GST_VIDEO_META_API_TYPE, 0);
+
+  if (qt_sink->context->gl_vtable->FenceSync)
+    gst_query_add_allocation_meta (query, GST_GL_SYNC_META_API_TYPE, 0);
+
+  return TRUE;
+
+  /* ERRORS */
+no_caps:
+  {
+    GST_DEBUG_OBJECT (bsink, "no caps specified");
+    return FALSE;
+  }
+invalid_caps:
+  {
+    GST_DEBUG_OBJECT (bsink, "invalid caps specified");
+    return FALSE;
+  }
+config_failed:
+  {
+    GST_DEBUG_OBJECT (bsink, "failed setting config");
+    return FALSE;
+  }
+}
diff --git a/ext/qt/gstqtsink.h b/ext/qt/gstqtsink.h
new file mode 100644
index 000000000..9a1cfbece
--- /dev/null
+++ b/ext/qt/gstqtsink.h
@@ -0,0 +1,81 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __GST_QT_SINK_H__
+#define __GST_QT_SINK_H__
+
+#include <gst/gst.h>
+#include <gst/video/gstvideosink.h>
+#include <gst/video/video.h>
+#include <gst/gl/gl.h>
+#include "qtitem.h"
+
+typedef struct _GstQtSink GstQtSink;
+typedef struct _GstQtSinkClass GstQtSinkClass;
+typedef struct _GstQtSinkPrivate GstQtSinkPrivate;
+
+G_BEGIN_DECLS
+
+GType gst_qt_sink_get_type (void);
+#define GST_TYPE_QT_SINK            (gst_qt_sink_get_type())
+#define GST_QT_SINK(obj)            (G_TYPE_CHECK_INSTANCE_CAST((obj),GST_TYPE_QT_SINK,GstQtSink))
+#define GST_QT_SINK_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST((klass),GST_TYPE_QT_SINK,GstQtSinkClass))
+#define GST_IS_QT_SINK(obj)         (G_TYPE_CHECK_INSTANCE_TYPE((obj),GST_TYPE_QT_SINK))
+#define GST_IS_QT_SINK_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE((klass),GST_TYPE_QT_SINK))
+#define GST_QT_SINK_CAST(obj)       ((GstQtSink*)(obj))
+
+/**
+ * GstQtSink:
+ *
+ * Opaque #GstQtSink object
+ */
+struct _GstQtSink
+{
+  /* <private> */
+  GstVideoSink          parent;
+
+  QtGLVideoItem        *widget;
+
+  GstVideoInfo          v_info;
+  GstBufferPool        *pool;
+
+  GstGLDisplay         *display;
+  GstGLContext         *context;
+  GstGLContext         *qt_context;
+
+  GstQtSinkPrivate  *priv;
+};
+
+/**
+ * GstQtSinkClass:
+ *
+ * The #GstQtSinkClass struct only contains private data
+ */
+struct _GstQtSinkClass
+{
+  /* <private> */
+  GstVideoSinkClass object_class;
+};
+
+GstQtSink *    gst_qt_sink_new (void);
+
+G_END_DECLS
+
+#endif /* __GST_QT_SINK_H__ */
diff --git a/ext/qt/qtitem.cc b/ext/qt/qtitem.cc
new file mode 100644
index 000000000..5a7ac2e69
--- /dev/null
+++ b/ext/qt/qtitem.cc
@@ -0,0 +1,491 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+
+#include <gst/video/video.h>
+#include <QGuiApplication>
+#include <QQuickWindow>
+#include <QSGSimpleTextureNode>
+#include "qtitem.h"
+#include "gstqsgtexture.h"
+
+#if GST_GL_HAVE_WINDOW_X11
+#include <QX11Info>
+#include <gst/gl/x11/gstgldisplay_x11.h>
+#include <gst/gl/x11/gstglcontext_glx.h>
+#endif
+
+#if GST_GL_HAVE_WINDOW_WAYLAND
+#include <gst/gl/wayland/gstgldisplay_wayland.h>
+#endif
+
+/**
+ * SECTION:gtkgstglwidget
+ * @short_description: a #GtkGLArea that renders GStreamer video #GstBuffers
+ * @see_also: #GtkGLArea, #GstBuffer
+ *
+ * #QtGLVideoItem is an #GtkWidget that renders GStreamer video buffers.
+ */
+
+#define GST_CAT_DEFAULT qt_item_debug
+GST_DEBUG_CATEGORY_STATIC (GST_CAT_DEFAULT);
+
+#define GTK_GST_GL_WIDGET_GET_PRIVATE(obj) (G_TYPE_INSTANCE_GET_PRIVATE ((obj), \
+    GTK_TYPE_GST_GL_WIDGET, QtGLVideoItemPrivate))
+
+#define DEFAULT_FORCE_ASPECT_RATIO  TRUE
+#define DEFAULT_PAR_N               0
+#define DEFAULT_PAR_D               1
+
+enum
+{
+  PROP_0,
+  PROP_FORCE_ASPECT_RATIO,
+  PROP_PIXEL_ASPECT_RATIO,
+};
+
+struct _QtGLVideoItemPrivate
+{
+  GMutex lock;
+
+  /* properties */
+  gboolean force_aspect_ratio;
+  gint par_n, par_d;
+
+  gint display_width;
+  gint display_height;
+
+  gboolean negotiated;
+  GstBuffer *buffer;
+  GstCaps *caps;
+  GstVideoInfo v_info;
+
+  gboolean initted;
+  GstGLDisplay *display;
+  QOpenGLContext *qt_context;
+  GstGLContext *other_context;
+  GstGLContext *context;
+};
+
+QtGLVideoItem::QtGLVideoItem()
+{
+  QGuiApplication *app = dynamic_cast<QGuiApplication *> (QCoreApplication::instance ());
+  static volatile gsize _debug;
+
+  g_assert (app != NULL);
+
+  if (g_once_init_enter (&_debug)) {
+    GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT, "qtglwidget", 0, "Qt GL Widget");
+    g_once_init_leave (&_debug, 1);
+  }
+
+  this->setFlag (QQuickItem::ItemHasContents, true);
+
+  this->priv = g_new0 (QtGLVideoItemPrivate, 1);
+
+  this->priv->force_aspect_ratio = DEFAULT_FORCE_ASPECT_RATIO;
+  this->priv->par_n = DEFAULT_PAR_N;
+  this->priv->par_d = DEFAULT_PAR_D;
+
+  g_mutex_init (&this->priv->lock);
+
+#if GST_GL_HAVE_WINDOW_X11
+  if (QString::fromUtf8 ("xcb") == app->platformName())
+    this->priv->display = (GstGLDisplay *)
+        gst_gl_display_x11_new_with_display (QX11Info::display ());
+#endif
+
+  if (!this->priv->display)
+    this->priv->display = gst_gl_display_new ();
+
+  connect(this, SIGNAL(windowChanged(QQuickWindow*)), this,
+          SLOT(handleWindowChanged(QQuickWindow*)));
+
+  GST_DEBUG ("%p init Qt Video Item", this);
+}
+
+QtGLVideoItem::~QtGLVideoItem()
+{
+  g_mutex_clear (&this->priv->lock);
+
+  g_free (this->priv);
+  this->priv = NULL;
+}
+
+void
+QtGLVideoItem::setDAR(gint num, gint den)
+{
+  this->priv->par_n = num;
+  this->priv->par_d = den;
+}
+
+void
+QtGLVideoItem::getDAR(gint * num, gint * den)
+{
+  if (num)
+    *num = this->priv->par_n;
+  if (den)
+    *den = this->priv->par_d;
+}
+
+void
+QtGLVideoItem::setForceAspectRatio(bool far)
+{
+  this->priv->force_aspect_ratio = far;
+}
+
+bool
+QtGLVideoItem::getForceAspectRatio()
+{
+  return this->priv->force_aspect_ratio;
+}
+
+QSGNode *
+QtGLVideoItem::updatePaintNode(QSGNode * oldNode,
+    UpdatePaintNodeData * updatePaintNodeData)
+{
+  QSGSimpleTextureNode *texNode = static_cast<QSGSimpleTextureNode *> (oldNode);
+  GstVideoRectangle src, dst, result;
+  GstQSGTexture *tex;
+
+  g_mutex_lock (&this->priv->lock);
+
+  GST_TRACE ("%p updatePaintNode", this);
+
+  if (!this->priv->caps) {
+    g_mutex_unlock (&this->priv->lock);
+    return NULL;
+  }
+
+  if (!texNode) {
+    texNode = new QSGSimpleTextureNode ();
+    tex = new GstQSGTexture ();
+    texNode->setTexture (tex);
+  } else {
+    tex = static_cast<GstQSGTexture *> (texNode->texture());
+  }
+
+  tex->setCaps (this->priv->caps);
+  tex->setBuffer (this->priv->buffer);
+
+  if (this->priv->force_aspect_ratio) {
+    src.w = this->priv->display_width;
+    src.h = this->priv->display_height;
+
+    dst.x = boundingRect().x();
+    dst.y = boundingRect().y();
+    dst.w = boundingRect().width();
+    dst.h = boundingRect().height();
+
+    gst_video_sink_center_rect (src, dst, &result, TRUE);
+  } else {
+    result.x = boundingRect().x();
+    result.y = boundingRect().y();
+    result.w = boundingRect().width();
+    result.h = boundingRect().height();
+  }
+
+  texNode->setRect (QRectF (result.x, result.y, result.w, result.h));
+
+  g_mutex_unlock (&this->priv->lock);
+
+  return texNode;
+}
+
+static void
+_reset (QtGLVideoItem * qt_item)
+{
+  gst_buffer_replace (&qt_item->priv->buffer, NULL);
+
+  gst_caps_replace (&qt_item->priv->caps, NULL);
+
+  qt_item->priv->negotiated = FALSE;
+  qt_item->priv->initted = FALSE;
+}
+
+void
+qt_item_set_buffer (QtGLVideoItem * widget, GstBuffer * buffer)
+{
+  g_return_if_fail (widget != NULL);
+  g_return_if_fail (widget->priv->negotiated);
+
+  g_mutex_lock (&widget->priv->lock);
+
+  gst_buffer_replace (&widget->priv->buffer, buffer);
+
+  QMetaObject::invokeMethod(widget, "update", Qt::QueuedConnection);
+
+  g_mutex_unlock (&widget->priv->lock);
+}
+
+void
+QtGLVideoItem::onSceneGraphInitialized ()
+{
+  GstGLPlatform platform;
+  GstGLAPI gl_api;
+  guintptr gl_handle;
+
+  GST_DEBUG ("scene graph initialization with Qt GL context %p",
+      this->window()->openglContext ());
+
+  if (this->priv->qt_context == this->window()->openglContext ())
+    return;
+
+  this->priv->qt_context = this->window()->openglContext ();
+  if (this->priv->qt_context == NULL) {
+    g_assert_not_reached ();
+    return;
+  }
+
+#if GST_GL_HAVE_WINDOW_X11
+  if (GST_IS_GL_DISPLAY_X11 (this->priv->display)) {
+    platform = GST_GL_PLATFORM_GLX;
+    gl_api = gst_gl_context_get_current_gl_api (NULL, NULL);
+    gl_handle = gst_gl_context_get_current_gl_context (platform);
+    if (gl_handle)
+      this->priv->other_context =
+          gst_gl_context_new_wrapped (this->priv->display, gl_handle,
+          platform, gl_api);
+  }
+#endif
+#if GST_GL_HAVE_WINDOW_WAYLAND
+  if (GST_IS_GL_DISPLAY_WAYLAND (this->priv->display)) {
+    platform = GST_GL_PLATFORM_EGL;
+    gl_api = gst_gl_context_get_current_gl_api (NULL, NULL);
+    gl_handle = gst_gl_context_get_current_gl_context (platform);
+    if (gl_handle)
+      this->priv->other_context =
+          gst_gl_context_new_wrapped (this->priv->display, gl_handle,
+          platform, gl_api);
+  }
+#endif
+
+  (void) platform;
+  (void) gl_api;
+  (void) gl_handle;
+
+  if (this->priv->other_context) {
+    GError *error = NULL;
+
+    gst_gl_context_activate (this->priv->other_context, TRUE);
+    if (!gst_gl_context_fill_info (this->priv->other_context, &error)) {
+      GST_ERROR ("%p failed to retreive qt context info: %s", this, error->message);
+      g_object_unref (this->priv->other_context);
+      this->priv->other_context = NULL;
+    } else {
+      gst_gl_display_filter_gl_api (this->priv->display, gst_gl_context_get_gl_api (this->priv->other_context));
+      gst_gl_context_activate (this->priv->other_context, FALSE);
+    }
+  }
+
+  GST_DEBUG ("%p created wrapped GL context %" GST_PTR_FORMAT, this,
+      this->priv->other_context);
+}
+
+void
+QtGLVideoItem::onSceneGraphInvalidated ()
+{
+  GST_FIXME ("%p scene graph invalidated", this);
+}
+
+gboolean
+qt_item_init_winsys (QtGLVideoItem * widget)
+{
+  g_return_val_if_fail (widget != NULL, FALSE);
+
+  g_mutex_lock (&widget->priv->lock);
+
+  if (widget->priv->display && widget->priv->qt_context
+      && widget->priv->other_context && widget->priv->context) {
+    /* already have the necessary state */
+    g_mutex_unlock (&widget->priv->lock);
+    return TRUE;
+  }
+
+  if (!GST_IS_GL_DISPLAY (widget->priv->display)) {
+    GST_ERROR ("%p failed to retreive display connection %" GST_PTR_FORMAT,
+        widget, widget->priv->display);
+    g_mutex_unlock (&widget->priv->lock);
+    return FALSE;
+  }
+
+  if (!GST_GL_IS_CONTEXT (widget->priv->other_context)) {
+    GST_ERROR ("%p failed to retreive wrapped context %" GST_PTR_FORMAT, widget,
+        widget->priv->other_context);
+    g_mutex_unlock (&widget->priv->lock);
+    return FALSE;
+  }
+
+  widget->priv->context = gst_gl_context_new (widget->priv->display);
+
+  if (!widget->priv->context) {
+    g_mutex_unlock (&widget->priv->lock);
+    return FALSE;
+  }
+
+  gst_gl_context_create (widget->priv->context, widget->priv->other_context,
+      NULL);
+
+  g_mutex_unlock (&widget->priv->lock);
+  return TRUE;
+}
+
+void
+QtGLVideoItem::handleWindowChanged(QQuickWindow *win)
+{
+  if (win) {
+    connect(win, SIGNAL(sceneGraphInitialized()), this, SLOT(onSceneGraphInitialized()), Qt::DirectConnection);
+    connect(win, SIGNAL(sceneGraphInvalidated()), this, SLOT(onSceneGraphInvalidated()), Qt::DirectConnection);
+  } else {
+    this->priv->qt_context = NULL;
+  }
+}
+
+static gboolean
+_calculate_par (QtGLVideoItem * widget, GstVideoInfo * info)
+{
+  gboolean ok;
+  gint width, height;
+  gint par_n, par_d;
+  gint display_par_n, display_par_d;
+  guint display_ratio_num, display_ratio_den;
+
+  width = GST_VIDEO_INFO_WIDTH (info);
+  height = GST_VIDEO_INFO_HEIGHT (info);
+
+  par_n = GST_VIDEO_INFO_PAR_N (info);
+  par_d = GST_VIDEO_INFO_PAR_D (info);
+
+  if (!par_n)
+    par_n = 1;
+
+  /* get display's PAR */
+  if (widget->priv->par_n != 0 && widget->priv->par_d != 0) {
+    display_par_n = widget->priv->par_n;
+    display_par_d = widget->priv->par_d;
+  } else {
+    display_par_n = 1;
+    display_par_d = 1;
+  }
+
+  ok = gst_video_calculate_display_ratio (&display_ratio_num,
+      &display_ratio_den, width, height, par_n, par_d, display_par_n,
+      display_par_d);
+
+  if (!ok)
+    return FALSE;
+
+  GST_LOG ("PAR: %u/%u DAR:%u/%u", par_n, par_d, display_par_n, display_par_d);
+
+  if (height % display_ratio_den == 0) {
+    GST_DEBUG ("keeping video height");
+    widget->priv->display_width = (guint)
+        gst_util_uint64_scale_int (height, display_ratio_num,
+        display_ratio_den);
+    widget->priv->display_height = height;
+  } else if (width % display_ratio_num == 0) {
+    GST_DEBUG ("keeping video width");
+    widget->priv->display_width = width;
+    widget->priv->display_height = (guint)
+        gst_util_uint64_scale_int (width, display_ratio_den, display_ratio_num);
+  } else {
+    GST_DEBUG ("approximating while keeping video height");
+    widget->priv->display_width = (guint)
+        gst_util_uint64_scale_int (height, display_ratio_num,
+        display_ratio_den);
+    widget->priv->display_height = height;
+  }
+  GST_DEBUG ("scaling to %dx%d", widget->priv->display_width,
+      widget->priv->display_height);
+
+  return TRUE;
+}
+
+gboolean
+qt_item_set_caps (QtGLVideoItem * widget, GstCaps * caps)
+{
+  GstVideoInfo v_info;
+
+  g_return_val_if_fail (widget != NULL, FALSE);
+  g_return_val_if_fail (GST_IS_CAPS (caps), FALSE);
+  g_return_val_if_fail (gst_caps_is_fixed (caps), FALSE);
+
+  if (widget->priv->caps && gst_caps_is_equal_fixed (widget->priv->caps, caps))
+    return TRUE;
+
+  if (!gst_video_info_from_caps (&v_info, caps))
+    return FALSE;
+
+  g_mutex_lock (&widget->priv->lock);
+
+  _reset (widget);
+
+  gst_caps_replace (&widget->priv->caps, caps);
+
+  if (!_calculate_par (widget, &v_info)) {
+    g_mutex_unlock (&widget->priv->lock);
+    return FALSE;
+  }
+
+  widget->priv->v_info = v_info;
+  widget->priv->negotiated = TRUE;
+
+  g_mutex_unlock (&widget->priv->lock);
+
+  return TRUE;
+}
+
+GstGLContext *
+qt_item_get_qt_context (QtGLVideoItem * qt_item)
+{
+  g_return_val_if_fail (qt_item != NULL, NULL);
+
+  if (!qt_item->priv->other_context)
+    return NULL;
+
+  return (GstGLContext *) gst_object_ref (qt_item->priv->other_context);
+}
+
+GstGLContext *
+qt_item_get_context (QtGLVideoItem * qt_item)
+{
+  g_return_val_if_fail (qt_item != NULL, NULL);
+
+  if (!qt_item->priv->context)
+    return NULL;
+
+  return (GstGLContext *) gst_object_ref (qt_item->priv->context);
+}
+
+GstGLDisplay *
+qt_item_get_display (QtGLVideoItem * qt_item)
+{
+  g_return_val_if_fail (qt_item != NULL, NULL);
+
+  if (!qt_item->priv->display)
+    return NULL;
+
+  return (GstGLDisplay *) gst_object_ref (qt_item->priv->display);
+}
diff --git a/ext/qt/qtitem.h b/ext/qt/qtitem.h
new file mode 100644
index 000000000..afd2869d8
--- /dev/null
+++ b/ext/qt/qtitem.h
@@ -0,0 +1,72 @@
+/*
+ * GStreamer
+ * Copyright (C) 2015 Matthew Waters <matthew@centricular.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __QT_ITEM_H__
+#define __QT_ITEM_H__
+
+#include <gst/gst.h>
+#include <gst/gl/gl.h>
+#include <QQuickItem>
+#include <QOpenGLContext>
+#include <QOpenGLFunctions>
+
+typedef struct _QtGLVideoItemPrivate QtGLVideoItemPrivate;
+
+class QtGLVideoItem : public QQuickItem, protected QOpenGLFunctions
+{
+    Q_OBJECT
+public:
+    QtGLVideoItem();
+    ~QtGLVideoItem();
+
+    void setDAR(gint, gint);
+    void getDAR(gint *, gint *);
+    void setForceAspectRatio(bool);
+    bool getForceAspectRatio();
+
+    /* private for C interface ... */
+    QtGLVideoItemPrivate *priv;
+
+private Q_SLOTS:
+    void handleWindowChanged(QQuickWindow * win);
+    void onSceneGraphInitialized();
+    void onSceneGraphInvalidated();
+
+protected:
+    QSGNode * updatePaintNode (QSGNode * oldNode, UpdatePaintNodeData * updatePaintNodeData);
+
+private:
+    void setViewportSize(const QSize &size);
+    void shareContext();
+
+    QSize m_viewportSize;
+};
+
+extern "C"
+{
+void            qt_item_set_buffer (QtGLVideoItem * widget, GstBuffer * buffer);
+gboolean        qt_item_set_caps (QtGLVideoItem * widget, GstCaps * caps);
+gboolean        qt_item_init_winsys (QtGLVideoItem * widget);
+GstGLContext *  qt_item_get_qt_context (QtGLVideoItem * qt_item);
+GstGLContext *  qt_item_get_context (QtGLVideoItem * qt_item);
+GstGLDisplay *  qt_item_get_display (QtGLVideoItem * qt_item);
+}
+
+#endif /* __QT_ITEM_H__ */