gstreamer/ext/qt/gstqtoverlay.cc

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/*
* GStreamer
* Copyright (C) 2020 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:gstqtoverlay
*
* qmlgloverlay provides a way to render an almost-arbitrary QML scene within
* GStreamer pipeline using the same OpenGL context that GStreamer uses
* internally. This avoids attempting to share multiple OpenGL contexts
* avoiding increased synchronisation points and attempting to share an OpenGL
* context at runtime which some drivers do not like. The Intel driver on
* Windows is a notable example of the last point.
*
* qmlgloverlay will attempt to retrieve the windowing system display connection
* that Qt is using (#GstGLDisplay). This may be different to any already
* existing window system display connection already in use in the pipeline for
* a number of reasons. A couple of examples of this are:
*
* 1. Adding qmlgloverlay to an already running pipeline
* 2. Not having any qmlgloverlay (or qmlglsink) element start up before any
* other OpenGL-based element in the pipeline.
*
* If one of these scenarios occurs, then there will be multiple OpenGL contexts
* in use in the pipeline. This means that either the pipeline will fail to
* start up correctly, a downstream element may reject buffers, or a complete
* GPU->System memory->GPU transfer is performed for every buffer.
*
* The requirement to avoid this is that all elements share the same
* #GstGLDisplay object and as Qt cannot currently share an existing window
* system display connection, GStreamer must use the window system display
* connection provided by Qt. This window system display connection can be
* retrieved by either a qmlglsink element or a qmlgloverlay element. The
* recommended usage is to have either element (qmlglsink or qmlgloverlay)
* be the first to propagate the #GstGLDisplay for the entire pipeline to use by
* setting either element to the READY element state before any other OpenGL
* element in the pipeline.
*
* In a dynamically adding qmlgloverlay (or qmlglsink) to a pipeline case,
* there are some considerations for ensuring that the window system display
* and OpenGL contexts are compatible with Qt. When the qmlgloverlay (or
* qmlglsink) element is added and brought up to READY, it will propagate it's
* own #GstGLDisplay using the #GstContext mechanism regardless of any existing
* #GstGLDisplay used by the pipeline previously. In order for the new
* #GstGLDisplay to be used, the application must then set the provided
* #GstGLDisplay containing #GstContext on the pipeline. This may effectively
* cause each OpenGL element to replace the window system display and also the
* OpenGL context it is using. As such this process may take a significant
* amount of time and resources as objects are recreated in the new OpenGL
* context.
*
* All instances of qmlgloverlay and qmlglsink will return the exact same
* #GstGLDisplay object while the pipeline is running regardless of whether
* any qmlgloverlay or qmlglsink elements are added or removed from the
* pipeline.
*
* The Qml scene will run at the pace of incoming buffers. One input buffer
* will cause a render of one output buffer. The timestamps on the input
* buffers are used to drive the animation time.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstqtelements.h"
#include "gstqtoverlay.h"
#include "qtglrenderer.h"
#include "gstqtglutility.h"
#include <QtGui/QGuiApplication>
#include <gst/gl/gstglfuncs.h>
#define GST_CAT_DEFAULT gst_debug_qt_gl_overlay
GST_DEBUG_CATEGORY (GST_CAT_DEFAULT);
static void gst_qt_overlay_finalize (GObject * object);
static void gst_qt_overlay_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * param_spec);
static void gst_qt_overlay_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * param_spec);
static gboolean gst_qt_overlay_gl_start (GstGLBaseFilter * bfilter);
static void gst_qt_overlay_gl_stop (GstGLBaseFilter * bfilter);
static gboolean gst_qt_overlay_gl_set_caps (GstGLBaseFilter * bfilter,
GstCaps * in_caps, GstCaps * out_caps);
static GstFlowReturn gst_qt_overlay_prepare_output_buffer (GstBaseTransform * btrans,
GstBuffer * buffer, GstBuffer ** outbuf);
static GstFlowReturn gst_qt_overlay_transform (GstBaseTransform * btrans,
GstBuffer * inbuf, GstBuffer * outbuf);
static GstStateChangeReturn gst_qt_overlay_change_state (GstElement * element,
GstStateChange transition);
enum
{
PROP_0,
PROP_WIDGET,
PROP_QML_SCENE,
PROP_ROOT_ITEM,
};
enum
{
SIGNAL_0,
SIGNAL_QML_SCENE_INITIALIZED,
SIGNAL_QML_SCENE_DESTROYED,
LAST_SIGNAL
};
static guint gst_qt_overlay_signals[LAST_SIGNAL] = { 0 };
#define gst_qt_overlay_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstQtOverlay, gst_qt_overlay,
GST_TYPE_GL_FILTER, GST_DEBUG_CATEGORY_INIT (GST_CAT_DEFAULT,
"qtoverlay", 0, "Qt Video Overlay"));
#define _do_init \
ret |= qt5_element_init (plugin);
GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (qmlgloverlay, "qmlgloverlay",
GST_RANK_NONE, GST_TYPE_QT_OVERLAY, _do_init);
static void
gst_qt_overlay_class_init (GstQtOverlayClass * klass)
{
GObjectClass *gobject_class;
GstElementClass *gstelement_class;
GstBaseTransformClass *btrans_class;
GstGLBaseFilterClass *glbasefilter_class;
GstGLFilterClass *glfilter_class;
GstElementClass *element_class;
gobject_class = (GObjectClass *) klass;
gstelement_class = (GstElementClass *) klass;
glbasefilter_class = (GstGLBaseFilterClass *) klass;
glfilter_class = (GstGLFilterClass *) klass;
btrans_class = (GstBaseTransformClass *) klass;
element_class = (GstElementClass *) klass;
gobject_class->set_property = gst_qt_overlay_set_property;
gobject_class->get_property = gst_qt_overlay_get_property;
gobject_class->finalize = gst_qt_overlay_finalize;
gst_element_class_set_metadata (gstelement_class, "Qt Video Overlay",
"Filter/QML/Overlay", "A filter that renders a QML scene onto a video stream",
"Matthew Waters <matthew@centricular.com>");
g_object_class_install_property (gobject_class, PROP_QML_SCENE,
g_param_spec_string ("qml-scene", "QML Scene",
"The contents of the QML scene", NULL,
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
g_object_class_install_property (gobject_class, PROP_WIDGET,
g_param_spec_pointer ("widget", "QQuickItem",
"The QQuickItem to place the input video in the object hierarchy",
(GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS)));
g_object_class_install_property (gobject_class, PROP_ROOT_ITEM,
g_param_spec_pointer ("root-item", "QQuickItem",
"The root QQuickItem from the qml-scene used to render",
(GParamFlags) (G_PARAM_READABLE | G_PARAM_STATIC_STRINGS)));
/**
* GstQmlGLOverlay::qml-scene-initialized
* @element: the #GstQmlGLOverlay
* @user_data: user provided data
*/
gst_qt_overlay_signals[SIGNAL_QML_SCENE_INITIALIZED] =
g_signal_new ("qml-scene-initialized", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL, G_TYPE_NONE, 0);
/**
* GstQmlGLOverlay::qml-scene-destroyed
* @element: the #GstQmlGLOverlay
* @user_data: user provided data
*/
gst_qt_overlay_signals[SIGNAL_QML_SCENE_DESTROYED] =
g_signal_new ("qml-scene-destroyed", G_TYPE_FROM_CLASS (klass),
G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL, G_TYPE_NONE, 0);
gst_gl_filter_add_rgba_pad_templates (glfilter_class);
btrans_class->prepare_output_buffer = gst_qt_overlay_prepare_output_buffer;
btrans_class->transform = gst_qt_overlay_transform;
glbasefilter_class->gl_start = gst_qt_overlay_gl_start;
glbasefilter_class->gl_stop = gst_qt_overlay_gl_stop;
glbasefilter_class->gl_set_caps = gst_qt_overlay_gl_set_caps;
element_class->change_state = gst_qt_overlay_change_state;
}
static void
gst_qt_overlay_init (GstQtOverlay * qt_overlay)
{
qt_overlay->widget = QSharedPointer<QtGLVideoItemInterface>();
}
static void
gst_qt_overlay_finalize (GObject * object)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (object);
qt_overlay->widget.clear();
G_OBJECT_CLASS (parent_class)->finalize (object);
}
static void
gst_qt_overlay_set_property (GObject * object, guint prop_id,
const GValue * value, GParamSpec * pspec)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (object);
switch (prop_id) {
case PROP_WIDGET: {
QtGLVideoItem *qt_item = static_cast<QtGLVideoItem *> (g_value_get_pointer (value));
if (qt_item)
qt_overlay->widget = qt_item->getInterface();
else
qt_overlay->widget.clear();
break;
}
case PROP_QML_SCENE:
g_free (qt_overlay->qml_scene);
qt_overlay->qml_scene = g_value_dup_string (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gst_qt_overlay_get_property (GObject * object, guint prop_id,
GValue * value, GParamSpec * pspec)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (object);
switch (prop_id) {
case PROP_WIDGET:
/* This is not really safe - the app needs to be
* sure the widget is going to be kept alive or
* this can crash */
if (qt_overlay->widget)
g_value_set_pointer (value, qt_overlay->widget->videoItem());
else
g_value_set_pointer (value, NULL);
break;
case PROP_QML_SCENE:
g_value_set_string (value, qt_overlay->qml_scene);
break;
case PROP_ROOT_ITEM:
GST_OBJECT_LOCK (qt_overlay);
if (qt_overlay->renderer) {
QQuickItem *root = qt_overlay->renderer->rootItem();
if (root)
g_value_set_pointer (value, root);
else
g_value_set_pointer (value, NULL);
} else {
g_value_set_pointer (value, NULL);
}
GST_OBJECT_UNLOCK (qt_overlay);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static gboolean
gst_qt_overlay_gl_start (GstGLBaseFilter * bfilter)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (bfilter);
QQuickItem *root;
GError *error = NULL;
GST_TRACE_OBJECT (bfilter, "using scene:\n%s", qt_overlay->qml_scene);
if (!qt_overlay->qml_scene || g_strcmp0 (qt_overlay->qml_scene, "") == 0) {
GST_ELEMENT_ERROR (bfilter, RESOURCE, NOT_FOUND, ("qml-scene property not set"), (NULL));
return FALSE;
}
if (!GST_GL_BASE_FILTER_CLASS (parent_class)->gl_start (bfilter))
return FALSE;
GST_OBJECT_LOCK (bfilter);
qt_overlay->renderer = new GstQuickRenderer;
if (!qt_overlay->renderer->init (bfilter->context, &error)) {
GST_ELEMENT_ERROR (GST_ELEMENT (bfilter), RESOURCE, NOT_FOUND,
("%s", error->message), (NULL));
delete qt_overlay->renderer;
qt_overlay->renderer = NULL;
GST_OBJECT_UNLOCK (bfilter);
return FALSE;
}
/* FIXME: Qml may do async loading and we need to propagate qml errors in that case as well */
if (!qt_overlay->renderer->setQmlScene (qt_overlay->qml_scene, &error)) {
GST_ELEMENT_ERROR (GST_ELEMENT (bfilter), RESOURCE, NOT_FOUND,
("%s", error->message), (NULL));
goto fail_renderer;
return FALSE;
}
root = qt_overlay->renderer->rootItem();
if (!root) {
GST_ELEMENT_ERROR (GST_ELEMENT (bfilter), RESOURCE, NOT_FOUND,
("Qml scene does not have a root item"), (NULL));
goto fail_renderer;
}
GST_OBJECT_UNLOCK (bfilter);
g_object_notify (G_OBJECT (qt_overlay), "root-item");
g_signal_emit (qt_overlay, gst_qt_overlay_signals[SIGNAL_QML_SCENE_INITIALIZED], 0);
return TRUE;
fail_renderer:
{
qt_overlay->renderer->cleanup();
delete qt_overlay->renderer;
qt_overlay->renderer = NULL;
GST_OBJECT_UNLOCK (bfilter);
return FALSE;
}
}
static void
gst_qt_overlay_gl_stop (GstGLBaseFilter * bfilter)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (bfilter);
GstQuickRenderer *renderer = NULL;
/* notify before actually destroying anything */
GST_OBJECT_LOCK (qt_overlay);
if (qt_overlay->renderer)
renderer = qt_overlay->renderer;
qt_overlay->renderer = NULL;
GST_OBJECT_UNLOCK (qt_overlay);
g_signal_emit (qt_overlay, gst_qt_overlay_signals[SIGNAL_QML_SCENE_DESTROYED], 0);
g_object_notify (G_OBJECT (qt_overlay), "root-item");
if (qt_overlay->widget)
qt_overlay->widget->setBuffer (NULL);
if (renderer) {
renderer->cleanup();
delete renderer;
}
GST_GL_BASE_FILTER_CLASS (parent_class)->gl_stop (bfilter);
}
static gboolean
gst_qt_overlay_gl_set_caps (GstGLBaseFilter * bfilter, GstCaps * in_caps,
GstCaps * out_caps)
{
GstGLFilter *filter = GST_GL_FILTER (bfilter);
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (bfilter);
if (!GST_GL_BASE_FILTER_CLASS (parent_class)->gl_set_caps (bfilter, in_caps, out_caps))
return FALSE;
qt_overlay->renderer->setSize (GST_VIDEO_INFO_WIDTH (&filter->out_info),
GST_VIDEO_INFO_HEIGHT (&filter->out_info));
return TRUE;
}
static GstFlowReturn
gst_qt_overlay_prepare_output_buffer (GstBaseTransform * btrans,
GstBuffer * buffer, GstBuffer ** outbuf)
{
GstBaseTransformClass *bclass = GST_BASE_TRANSFORM_GET_CLASS (btrans);
GstGLBaseFilter *bfilter = GST_GL_BASE_FILTER (btrans);
GstGLFilter *filter = GST_GL_FILTER (btrans);
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (btrans);
GstGLMemory *out_mem;
GstGLSyncMeta *sync_meta;
if (qt_overlay->widget) {
qt_overlay->widget->setCaps (bfilter->in_caps);
qt_overlay->widget->setBuffer (buffer);
}
/* XXX: is this the correct ts to drive the animation */
out_mem = qt_overlay->renderer->generateOutput (GST_BUFFER_PTS (buffer));
if (!out_mem) {
GST_ERROR_OBJECT (qt_overlay, "Failed to generate output");
return GST_FLOW_ERROR;
}
*outbuf = gst_buffer_new ();
gst_buffer_append_memory (*outbuf, (GstMemory *) out_mem);
gst_buffer_add_video_meta (*outbuf, (GstVideoFrameFlags) 0,
GST_VIDEO_INFO_FORMAT (&filter->out_info),
GST_VIDEO_INFO_WIDTH (&filter->in_info),
GST_VIDEO_INFO_HEIGHT (&filter->out_info));
sync_meta = gst_buffer_add_gl_sync_meta (bfilter->context, *outbuf);
gst_gl_sync_meta_set_sync_point (sync_meta, bfilter->context);
bclass->copy_metadata (btrans, buffer, *outbuf);
return GST_FLOW_OK;
}
static GstFlowReturn
gst_qt_overlay_transform (GstBaseTransform * btrans, GstBuffer * inbuf,
GstBuffer * outbuf)
{
return GST_FLOW_OK;
}
static GstStateChangeReturn
gst_qt_overlay_change_state (GstElement * element,
GstStateChange transition)
{
GstQtOverlay *qt_overlay = GST_QT_OVERLAY (element);
GstGLBaseFilter *filter = GST_GL_BASE_FILTER (element);
GstStateChangeReturn ret = GST_STATE_CHANGE_SUCCESS;
GST_DEBUG_OBJECT (filter, "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: {
QGuiApplication *app;
GstGLDisplay *display = NULL;
app = static_cast<QGuiApplication *> (QCoreApplication::instance ());
if (!app) {
GST_ELEMENT_ERROR (element, RESOURCE, NOT_FOUND,
("%s", "Failed to connect to Qt"),
("%s", "Could not retrieve QGuiApplication instance"));
return GST_STATE_CHANGE_FAILURE;
}
display = gst_qt_get_gl_display ();
if (display != filter->display)
/* always propagate. The application may need to choose between window
* system display connections */
gst_gl_element_propagate_display_context (GST_ELEMENT (qt_overlay), display);
gst_object_unref (display);
break;
}
default:
break;
}
ret = GST_ELEMENT_CLASS (parent_class)->change_state (element, transition);
if (ret == GST_STATE_CHANGE_FAILURE)
return ret;
switch (transition) {
default:
break;
}
return ret;
}