GStreamer backend changes for media probing API.

QGstreamerPlayerSession: Using GStreamer buffer probes
to access media data.

Change-Id: Ibc056283fdedaebba90456cc4e86ab63eae5f5f7
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>

src/plugins/gstreamer/qgstreamervideoprobecontrol.cpp

@@ -0,0 +1,117 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** This file is part of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** GNU Lesser General Public License Usage
+** This file may be used under the terms of the GNU Lesser General Public
+** License version 2.1 as published by the Free Software Foundation and
+** appearing in the file LICENSE.LGPL included in the packaging of this
+** file. Please review the following information to ensure the GNU Lesser
+** General Public License version 2.1 requirements will be met:
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU General
+** Public License version 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of this
+** file. Please review the following information to ensure the GNU General
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qgstreamervideoprobecontrol.h"
+#include <private/qvideosurfacegstsink_p.h>
+#include <private/qgstvideobuffer_p.h>
+
+QGstreamerVideoProbeControl::QGstreamerVideoProbeControl(QObject *parent)
+    : QMediaVideoProbeControl(parent)
+    , m_flushing(false)
+    , m_frameProbed(false)
+{
+
+}
+
+QGstreamerVideoProbeControl::~QGstreamerVideoProbeControl()
+{
+
+}
+
+void QGstreamerVideoProbeControl::startFlushing()
+{
+    m_flushing = true;
+
+    {
+        QMutexLocker locker(&m_frameMutex);
+        m_pendingFrame = QVideoFrame();
+    }
+
+    // only emit flush if at least one frame was probed
+    if (m_frameProbed)
+        emit flush();
+}
+
+void QGstreamerVideoProbeControl::stopFlushing()
+{
+    m_flushing = false;
+}
+
+void QGstreamerVideoProbeControl::bufferProbed(GstBuffer* buffer)
+{
+    if (m_flushing)
+        return;
+
+    GstCaps* caps = gst_buffer_get_caps(buffer);
+    if (!caps)
+        return;
+
+    int bytesPerLine = 0;
+    QVideoSurfaceFormat format = QVideoSurfaceGstSink::formatForCaps(caps, &bytesPerLine);
+    gst_caps_unref(caps);
+    if (!format.isValid() || !bytesPerLine)
+        return;
+
+    QVideoFrame frame = QVideoFrame(new QGstVideoBuffer(buffer, bytesPerLine),
+                                    format.frameSize(), format.pixelFormat());
+
+    QVideoSurfaceGstSink::setFrameTimeStamps(&frame, buffer);
+
+    m_frameProbed = true;
+
+    {
+        QMutexLocker locker(&m_frameMutex);
+        m_pendingFrame = frame;
+        QMetaObject::invokeMethod(this, "frameProbed", Qt::QueuedConnection);
+    }
+}
+
+void QGstreamerVideoProbeControl::frameProbed()
+{
+    QVideoFrame frame;
+    {
+        QMutexLocker locker(&m_frameMutex);
+        if (!m_pendingFrame.isValid())
+            return;
+        frame = m_pendingFrame;
+    }
+    emit videoFrameProbed(frame);
+}