path: root/src/gsttools/qvideosurfacegstsink.cpp

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#include <qabstractvideosurface.h>
#include <qvideoframe.h>
#include <QDebug>
#include <QMap>
#include <QDebug>
#include <QThread>

#include <private/qmediapluginloader_p.h>
#include "qgstvideobuffer_p.h"

#if defined(HAVE_XVIDEO)
#include "qgstxvimagebuffer_p.h"
#endif

#include "qvideosurfacegstsink_p.h"

//#define DEBUG_VIDEO_SURFACE_SINK

QT_BEGIN_NAMESPACE

Q_GLOBAL_STATIC_WITH_ARGS(QMediaPluginLoader, bufferPoolLoader,
        (QGstBufferPoolInterface_iid, QLatin1String("video/bufferpool"), Qt::CaseInsensitive))


QVideoSurfaceGstDelegate::QVideoSurfaceGstDelegate(
    QAbstractVideoSurface *surface)
    : m_surface(surface)
    , m_pool(0)
    , m_renderReturn(GST_FLOW_ERROR)
    , m_lastPrerolledBuffer(0)
    , m_bytesPerLine(0)
    , m_startCanceled(false)
{
    if (m_surface) {
        foreach (QObject *instance, bufferPoolLoader()->instances(QGstBufferPoolPluginKey)) {
            QGstBufferPoolInterface* plugin = qobject_cast<QGstBufferPoolInterface*>(instance);
            if (plugin) {
                m_pools.append(plugin);
            }
        }
#ifdef HAVE_XVIDEO
        m_pools.append(new QGstXvImageBufferPool(this));
#endif
        updateSupportedFormats();
        connect(m_surface, SIGNAL(supportedFormatsChanged()), this, SLOT(updateSupportedFormats()));
    }
}

QVideoSurfaceGstDelegate::~QVideoSurfaceGstDelegate()
{
    setLastPrerolledBuffer(0);
}

QList<QVideoFrame::PixelFormat> QVideoSurfaceGstDelegate::supportedPixelFormats(QAbstractVideoBuffer::HandleType handleType) const
{
    QMutexLocker locker(const_cast<QMutex *>(&m_mutex));

    if (!m_surface)
        return QList<QVideoFrame::PixelFormat>();
    else if (handleType == QAbstractVideoBuffer::NoHandle)
        return m_supportedPixelFormats;
    else if (handleType == m_pool->handleType())
        return m_supportedPoolPixelFormats;
    else
        return m_surface->supportedPixelFormats(handleType);
}

QVideoSurfaceFormat QVideoSurfaceGstDelegate::surfaceFormat() const
{
    QMutexLocker locker(const_cast<QMutex *>(&m_mutex));
    return m_format;
}

bool QVideoSurfaceGstDelegate::start(const QVideoSurfaceFormat &format, int bytesPerLine)
{
    if (!m_surface)
        return false;

    QMutexLocker locker(&m_mutex);

    m_format = format;
    m_bytesPerLine = bytesPerLine;

    if (QThread::currentThread() == thread()) {
        m_started = !m_surface.isNull() ? m_surface->start(m_format) : false;
    } else {
        m_started = false;
        m_startCanceled = false;
        QMetaObject::invokeMethod(this, "queuedStart", Qt::QueuedConnection);

        /*
        Waiting for start() to be invoked in the main thread may block
        if gstreamer blocks the main thread until this call is finished.
        This situation is rare and usually caused by setState(Null)
        while pipeline is being prerolled.

        The proper solution to this involves controlling gstreamer pipeline from
        other thread than video surface.

        Currently start() fails if wait() timed out.
        */
        if (!m_setupCondition.wait(&m_mutex, 1000)) {
            qWarning() << "Failed to start video surface due to main thread blocked.";
            m_startCanceled = true;
        }
    }

    m_format = m_surface->surfaceFormat();

    return m_started;
}

void QVideoSurfaceGstDelegate::stop()
{
    if (!m_surface)
        return;

    QMutexLocker locker(&m_mutex);

    if (QThread::currentThread() == thread()) {
        if (!m_surface.isNull())
            m_surface->stop();
    } else {
        QMetaObject::invokeMethod(this, "queuedStop", Qt::QueuedConnection);

        // Waiting for stop() to be invoked in the main thread may block
        // if gstreamer blocks the main thread until this call is finished.
        m_setupCondition.wait(&m_mutex, 500);
    }

    m_started = false;
}

bool QVideoSurfaceGstDelegate::isActive()
{
    QMutexLocker locker(&m_mutex);
    return !m_surface.isNull() && m_surface->isActive();
}

void QVideoSurfaceGstDelegate::clearPoolBuffers()
{
    QMutexLocker locker(&m_poolMutex);
    if (m_pool)
        m_pool->clear();
}

GstFlowReturn QVideoSurfaceGstDelegate::render(GstBuffer *buffer)
{
    if (!m_surface) {
        qWarning() << "Rendering video frame to deleted surface, skip.";
        //return GST_FLOW_NOT_NEGOTIATED;
        return GST_FLOW_OK;
    }

    QMutexLocker locker(&m_mutex);

    QAbstractVideoBuffer *videoBuffer = 0;

    if (m_pool)
        videoBuffer = m_pool->prepareVideoBuffer(buffer, m_bytesPerLine);

    if (!videoBuffer)
        videoBuffer = new QGstVideoBuffer(buffer, m_bytesPerLine);

    m_frame = QVideoFrame(
            videoBuffer,
            m_format.frameSize(),
            m_format.pixelFormat());

    QVideoSurfaceGstSink::setFrameTimeStamps(&m_frame, buffer);

    m_renderReturn = GST_FLOW_OK;

    if (QThread::currentThread() == thread()) {
        if (!m_surface.isNull())
            m_surface->present(m_frame);
    } else {
        QMetaObject::invokeMethod(this, "queuedRender", Qt::QueuedConnection);
        m_renderCondition.wait(&m_mutex, 300);
    }

    m_frame = QVideoFrame();
    return m_renderReturn;
}

void QVideoSurfaceGstDelegate::setLastPrerolledBuffer(GstBuffer *prerolledBuffer)
{
    // discard previously stored buffer
    if (m_lastPrerolledBuffer) {
        gst_buffer_unref(m_lastPrerolledBuffer);
        m_lastPrerolledBuffer = 0;
    }

    if (!prerolledBuffer)
        return;

    // store a reference to the buffer
    Q_ASSERT(!m_lastPrerolledBuffer);
    m_lastPrerolledBuffer = prerolledBuffer;
    gst_buffer_ref(m_lastPrerolledBuffer);
}

void QVideoSurfaceGstDelegate::queuedStart()
{
    if (!m_startCanceled) {
        QMutexLocker locker(&m_mutex);
        m_started = m_surface->start(m_format);
        m_setupCondition.wakeAll();
    }
}

void QVideoSurfaceGstDelegate::queuedStop()
{
    QMutexLocker locker(&m_mutex);

    m_surface->stop();

    m_setupCondition.wakeAll();
}

void QVideoSurfaceGstDelegate::queuedRender()
{
    QMutexLocker locker(&m_mutex);

    if (m_surface.isNull()) {
        qWarning() << "Rendering video frame to deleted surface, skip the frame";
        m_renderReturn = GST_FLOW_OK;
    } else if (m_surface->present(m_frame)) {
        m_renderReturn = GST_FLOW_OK;
    } else {
        switch (m_surface->error()) {
        case QAbstractVideoSurface::NoError:
            m_renderReturn = GST_FLOW_OK;
            break;
        case QAbstractVideoSurface::StoppedError:
            //It's likely we are in process of changing video output
            //and the surface is already stopped, ignore the frame
            m_renderReturn = GST_FLOW_OK;
            break;
        default:
            qWarning() << "Failed to render video frame:" << m_surface->error();
            m_renderReturn = GST_FLOW_OK;
            break;
        }
    }

    m_renderCondition.wakeAll();
}

void QVideoSurfaceGstDelegate::updateSupportedFormats()
{
    QGstBufferPoolInterface *newPool = 0;
    foreach (QGstBufferPoolInterface *pool, m_pools) {
        if (!m_surface->supportedPixelFormats(pool->handleType()).isEmpty()) {
            newPool = pool;
            break;
        }
    }

    if (newPool != m_pool) {
        QMutexLocker lock(&m_poolMutex);

        if (m_pool)
            m_pool->clear();
        m_pool = newPool;
    }

    QMutexLocker locker(&m_mutex);

    m_supportedPixelFormats.clear();
    m_supportedPoolPixelFormats.clear();
    if (m_surface) {
        m_supportedPixelFormats = m_surface->supportedPixelFormats();
        if (m_pool)
            m_supportedPoolPixelFormats = m_surface->supportedPixelFormats(m_pool->handleType());
    }
}

struct YuvFormat
{
    QVideoFrame::PixelFormat pixelFormat;
    guint32 fourcc;
    int bitsPerPixel;
};

static const YuvFormat qt_yuvColorLookup[] =
{
    { QVideoFrame::Format_YUV420P, GST_MAKE_FOURCC('I','4','2','0'), 8 },
    { QVideoFrame::Format_YV12,    GST_MAKE_FOURCC('Y','V','1','2'), 8 },
    { QVideoFrame::Format_UYVY,    GST_MAKE_FOURCC('U','Y','V','Y'), 16 },
    { QVideoFrame::Format_YUYV,    GST_MAKE_FOURCC('Y','U','Y','2'), 16 },
    { QVideoFrame::Format_NV12,    GST_MAKE_FOURCC('N','V','1','2'), 8 },
    { QVideoFrame::Format_NV21,    GST_MAKE_FOURCC('N','V','2','1'), 8 },
    { QVideoFrame::Format_AYUV444, GST_MAKE_FOURCC('A','Y','U','V'), 32 }
};

static int indexOfYuvColor(QVideoFrame::PixelFormat format)
{
    const int count = sizeof(qt_yuvColorLookup) / sizeof(YuvFormat);

    for (int i = 0; i < count; ++i)
        if (qt_yuvColorLookup[i].pixelFormat == format)
            return i;

    return -1;
}

static int indexOfYuvColor(guint32 fourcc)
{
    const int count = sizeof(qt_yuvColorLookup) / sizeof(YuvFormat);

    for (int i = 0; i < count; ++i)
        if (qt_yuvColorLookup[i].fourcc == fourcc)
            return i;

    return -1;
}

struct RgbFormat
{
    QVideoFrame::PixelFormat pixelFormat;
    int bitsPerPixel;
    int depth;
    int endianness;
    int red;
    int green;
    int blue;
    int alpha;
};

static const RgbFormat qt_rgbColorLookup[] =
{
    { QVideoFrame::Format_RGB32 , 32, 24, 4321, 0x0000FF00, 0x00FF0000, 0xFF000000, 0x00000000 },
    { QVideoFrame::Format_RGB32 , 32, 24, 1234, 0x00FF0000, 0x0000FF00, 0x000000FF, 0x00000000 },
    { QVideoFrame::Format_BGR32 , 32, 24, 4321, 0xFF000000, 0x00FF0000, 0x0000FF00, 0x00000000 },
    { QVideoFrame::Format_BGR32 , 32, 24, 1234, 0x000000FF, 0x0000FF00, 0x00FF0000, 0x00000000 },
    { QVideoFrame::Format_ARGB32, 32, 24, 4321, 0x0000FF00, 0x00FF0000, 0xFF000000, 0x000000FF },
    { QVideoFrame::Format_ARGB32, 32, 24, 1234, 0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000 },
    { QVideoFrame::Format_RGB24 , 24, 24, 4321, 0x00FF0000, 0x0000FF00, 0x000000FF, 0x00000000 },
    { QVideoFrame::Format_BGR24 , 24, 24, 4321, 0x000000FF, 0x0000FF00, 0x00FF0000, 0x00000000 },
    { QVideoFrame::Format_RGB565, 16, 16, 1234, 0x0000F800, 0x000007E0, 0x0000001F, 0x00000000 }
};

static int indexOfRgbColor(
        int bits, int depth, int endianness, int red, int green, int blue, int alpha)
{
    const int count = sizeof(qt_rgbColorLookup) / sizeof(RgbFormat);

    for (int i = 0; i < count; ++i) {
        if (qt_rgbColorLookup[i].bitsPerPixel == bits
            && qt_rgbColorLookup[i].depth == depth
            && qt_rgbColorLookup[i].endianness == endianness
            && qt_rgbColorLookup[i].red == red
            && qt_rgbColorLookup[i].green == green
            && qt_rgbColorLookup[i].blue == blue
            && qt_rgbColorLookup[i].alpha == alpha) {
            return i;
        }
    }
    return -1;
}

static GstVideoSinkClass *sink_parent_class;

#define VO_SINK(s) QVideoSurfaceGstSink *sink(reinterpret_cast<QVideoSurfaceGstSink *>(s))

QVideoSurfaceGstSink *QVideoSurfaceGstSink::createSink(QAbstractVideoSurface *surface)
{
    QVideoSurfaceGstSink *sink = reinterpret_cast<QVideoSurfaceGstSink *>(
            g_object_new(QVideoSurfaceGstSink::get_type(), 0));

    sink->delegate = new QVideoSurfaceGstDelegate(surface);

    g_signal_connect(G_OBJECT(sink), "notify::show-preroll-frame", G_CALLBACK(handleShowPrerollChange), sink);

    return sink;
}

GType QVideoSurfaceGstSink::get_type()
{
    static GType type = 0;

    if (type == 0) {
        static const GTypeInfo info =
        {
            sizeof(QVideoSurfaceGstSinkClass),                    // class_size
            base_init,                                         // base_init
            NULL,                                              // base_finalize
            class_init,                                        // class_init
            NULL,                                              // class_finalize
            NULL,                                              // class_data
            sizeof(QVideoSurfaceGstSink),                         // instance_size
            0,                                                 // n_preallocs
            instance_init,                                     // instance_init
            0                                                  // value_table
        };

        type = g_type_register_static(
                GST_TYPE_VIDEO_SINK, "QVideoSurfaceGstSink", &info, GTypeFlags(0));
    }

    return type;
}

void QVideoSurfaceGstSink::class_init(gpointer g_class, gpointer class_data)
{
    Q_UNUSED(class_data);

    sink_parent_class = reinterpret_cast<GstVideoSinkClass *>(g_type_class_peek_parent(g_class));

    GstBaseSinkClass *base_sink_class = reinterpret_cast<GstBaseSinkClass *>(g_class);
    base_sink_class->get_caps = QVideoSurfaceGstSink::get_caps;
    base_sink_class->set_caps = QVideoSurfaceGstSink::set_caps;
    base_sink_class->buffer_alloc = QVideoSurfaceGstSink::buffer_alloc;
    base_sink_class->start = QVideoSurfaceGstSink::start;
    base_sink_class->stop = QVideoSurfaceGstSink::stop;
    // base_sink_class->unlock = QVideoSurfaceGstSink::unlock; // Not implemented.
    base_sink_class->event = QVideoSurfaceGstSink::event;
    base_sink_class->preroll = QVideoSurfaceGstSink::preroll;
    base_sink_class->render = QVideoSurfaceGstSink::render;

    GstElementClass *element_class = reinterpret_cast<GstElementClass *>(g_class);
    element_class->change_state = QVideoSurfaceGstSink::change_state;

    GObjectClass *object_class = reinterpret_cast<GObjectClass *>(g_class);
    object_class->finalize = QVideoSurfaceGstSink::finalize;
}

void QVideoSurfaceGstSink::base_init(gpointer g_class)
{
    static GstStaticPadTemplate sink_pad_template = GST_STATIC_PAD_TEMPLATE(
            "sink", GST_PAD_SINK, GST_PAD_ALWAYS, GST_STATIC_CAPS(
                    "video/x-raw-rgb, "
                    "framerate = (fraction) [ 0, MAX ], "
                    "width = (int) [ 1, MAX ], "
                    "height = (int) [ 1, MAX ]; "
                    "video/x-raw-yuv, "
                    "framerate = (fraction) [ 0, MAX ], "
                    "width = (int) [ 1, MAX ], "
                    "height = (int) [ 1, MAX ]"));

    gst_element_class_add_pad_template(
            GST_ELEMENT_CLASS(g_class), gst_static_pad_template_get(&sink_pad_template));
}

void QVideoSurfaceGstSink::instance_init(GTypeInstance *instance, gpointer g_class)
{
    VO_SINK(instance);

    Q_UNUSED(g_class);

    sink->delegate = 0;

    sink->lastRequestedCaps = 0;
    sink->lastBufferCaps = 0;
    sink->lastSurfaceFormat = new QVideoSurfaceFormat;
}

void QVideoSurfaceGstSink::finalize(GObject *object)
{
    VO_SINK(object);

    delete sink->lastSurfaceFormat;
    sink->lastSurfaceFormat = 0;

    if (sink->lastBufferCaps)
        gst_caps_unref(sink->lastBufferCaps);
    sink->lastBufferCaps = 0;

    if (sink->lastRequestedCaps)
        gst_caps_unref(sink->lastRequestedCaps);
    sink->lastRequestedCaps = 0;

    delete sink->delegate;

    // Chain up
    G_OBJECT_CLASS(sink_parent_class)->finalize(object);
}

GstStateChangeReturn QVideoSurfaceGstSink::change_state(
        GstElement *element, GstStateChange transition)
{
    Q_UNUSED(element);

    return GST_ELEMENT_CLASS(sink_parent_class)->change_state(
            element, transition);
}

GstCaps *QVideoSurfaceGstSink::get_caps(GstBaseSink *base)
{
    VO_SINK(base);

    GstCaps *caps = gst_caps_new_empty();

    // Find the supported pixel formats
    // with buffer pool specific formats listed first
    QList<QVideoFrame::PixelFormat> supportedFormats;

    QList<QVideoFrame::PixelFormat> poolHandleFormats;
    sink->delegate->poolMutex()->lock();
    QGstBufferPoolInterface *pool = sink->delegate->pool();
    if (pool)
        poolHandleFormats = sink->delegate->supportedPixelFormats(pool->handleType());
    sink->delegate->poolMutex()->unlock();

    supportedFormats = poolHandleFormats;
    foreach (QVideoFrame::PixelFormat format, sink->delegate->supportedPixelFormats()) {
        if (!poolHandleFormats.contains(format))
            supportedFormats.append(format);
    }

    foreach (QVideoFrame::PixelFormat format, supportedFormats) {
        int index = indexOfYuvColor(format);

        if (index != -1) {
            gst_caps_append_structure(caps, gst_structure_new(
                    "video/x-raw-yuv",
                    "framerate", GST_TYPE_FRACTION_RANGE, 0, 1, INT_MAX, 1,
                    "width"    , GST_TYPE_INT_RANGE, 1, INT_MAX,
                    "height"   , GST_TYPE_INT_RANGE, 1, INT_MAX,
                    "format"   , GST_TYPE_FOURCC, qt_yuvColorLookup[index].fourcc,
                    NULL));
            continue;
        }

        const int count = sizeof(qt_rgbColorLookup) / sizeof(RgbFormat);

        for (int i = 0; i < count; ++i) {
            if (qt_rgbColorLookup[i].pixelFormat == format) {
                GstStructure *structure = gst_structure_new(
                        "video/x-raw-rgb",
                        "framerate" , GST_TYPE_FRACTION_RANGE, 0, 1, INT_MAX, 1,
                        "width"     , GST_TYPE_INT_RANGE, 1, INT_MAX,
                        "height"    , GST_TYPE_INT_RANGE, 1, INT_MAX,
                        "bpp"       , G_TYPE_INT, qt_rgbColorLookup[i].bitsPerPixel,
                        "depth"     , G_TYPE_INT, qt_rgbColorLookup[i].depth,
                        "endianness", G_TYPE_INT, qt_rgbColorLookup[i].endianness,
                        "red_mask"  , G_TYPE_INT, qt_rgbColorLookup[i].red,
                        "green_mask", G_TYPE_INT, qt_rgbColorLookup[i].green,
                        "blue_mask" , G_TYPE_INT, qt_rgbColorLookup[i].blue,
                        NULL);

                if (qt_rgbColorLookup[i].alpha != 0) {
                    gst_structure_set(
                            structure, "alpha_mask", G_TYPE_INT, qt_rgbColorLookup[i].alpha, NULL);
                }
                gst_caps_append_structure(caps, structure);
            }
        }
    }

    return caps;
}

gboolean QVideoSurfaceGstSink::set_caps(GstBaseSink *base, GstCaps *caps)
{
    VO_SINK(base);

#ifdef DEBUG_VIDEO_SURFACE_SINK
    qDebug() << "set_caps:";
    qDebug() << gst_caps_to_string(caps);
#endif

    if (!caps) {
        sink->delegate->stop();

        return TRUE;
    } else {
        int bytesPerLine = 0;
        QGstBufferPoolInterface *pool = sink->delegate->pool();
        QAbstractVideoBuffer::HandleType handleType =
                pool ? pool->handleType() : QAbstractVideoBuffer::NoHandle;

        QVideoSurfaceFormat format = formatForCaps(caps, &bytesPerLine, handleType);

        if (sink->delegate->isActive()) {
            QVideoSurfaceFormat surfaceFormst = sink->delegate->surfaceFormat();

            if (format.pixelFormat() == surfaceFormst.pixelFormat() &&
                format.frameSize() == surfaceFormst.frameSize())
                return TRUE;
            else
                sink->delegate->stop();
        }

        if (sink->lastRequestedCaps)
            gst_caps_unref(sink->lastRequestedCaps);
        sink->lastRequestedCaps = 0;

#ifdef DEBUG_VIDEO_SURFACE_SINK
        qDebug() << "Staring video surface, format:";
        qDebug() << format;
        qDebug() << "bytesPerLine:" << bytesPerLine;
#endif

        if (sink->delegate->start(format, bytesPerLine))
            return TRUE;
        else
            qWarning() << "Failed to start video surface";
    }

    return FALSE;
}

QVideoSurfaceFormat QVideoSurfaceGstSink::formatForCaps(GstCaps *caps, int *bytesPerLine, QAbstractVideoBuffer::HandleType handleType)
{
    const GstStructure *structure = gst_caps_get_structure(caps, 0);

    QVideoFrame::PixelFormat pixelFormat = QVideoFrame::Format_Invalid;
    int bitsPerPixel = 0;

    QSize size;
    gst_structure_get_int(structure, "width", &size.rwidth());
    gst_structure_get_int(structure, "height", &size.rheight());

    if (qstrcmp(gst_structure_get_name(structure), "video/x-raw-yuv") == 0) {
        guint32 fourcc = 0;
        gst_structure_get_fourcc(structure, "format", &fourcc);

        int index = indexOfYuvColor(fourcc);
        if (index != -1) {
            pixelFormat = qt_yuvColorLookup[index].pixelFormat;
            bitsPerPixel = qt_yuvColorLookup[index].bitsPerPixel;
        }
    } else if (qstrcmp(gst_structure_get_name(structure), "video/x-raw-rgb") == 0) {
        int depth = 0;
        int endianness = 0;
        int red = 0;
        int green = 0;
        int blue = 0;
        int alpha = 0;

        gst_structure_get_int(structure, "bpp", &bitsPerPixel);
        gst_structure_get_int(structure, "depth", &depth);
        gst_structure_get_int(structure, "endianness", &endianness);
        gst_structure_get_int(structure, "red_mask", &red);
        gst_structure_get_int(structure, "green_mask", &green);
        gst_structure_get_int(structure, "blue_mask", &blue);
        gst_structure_get_int(structure, "alpha_mask", &alpha);

        int index = indexOfRgbColor(bitsPerPixel, depth, endianness, red, green, blue, alpha);

        if (index != -1)
            pixelFormat = qt_rgbColorLookup[index].pixelFormat;
    }

    if (pixelFormat != QVideoFrame::Format_Invalid) {
        QVideoSurfaceFormat format(size, pixelFormat, handleType);

        QPair<int, int> rate;
        gst_structure_get_fraction(structure, "framerate", &rate.first, &rate.second);

        if (rate.second)
            format.setFrameRate(qreal(rate.first)/rate.second);

        gint aspectNum = 0;
        gint aspectDenum = 0;
        if (gst_structure_get_fraction(
                structure, "pixel-aspect-ratio", &aspectNum, &aspectDenum)) {
            if (aspectDenum > 0)
                format.setPixelAspectRatio(aspectNum, aspectDenum);
        }

        if (bytesPerLine)
            *bytesPerLine = ((size.width() * bitsPerPixel / 8) + 3) & ~3;

        return format;
    }

    return QVideoSurfaceFormat();
}

void QVideoSurfaceGstSink::setFrameTimeStamps(QVideoFrame *frame, GstBuffer *buffer)
{
    qint64 startTime = GST_BUFFER_TIMESTAMP(buffer);
    if (startTime >= 0) {
        frame->setStartTime(startTime/G_GINT64_CONSTANT (1000000));

        qint64 duration = GST_BUFFER_DURATION(buffer);
        if (duration >= 0)
            frame->setEndTime((startTime + duration)/G_GINT64_CONSTANT (1000000));
    }
}

void QVideoSurfaceGstSink::handleShowPrerollChange(GObject *o, GParamSpec *p, gpointer d)
{
    Q_UNUSED(o);
    Q_UNUSED(p);
    QVideoSurfaceGstSink *sink = reinterpret_cast<QVideoSurfaceGstSink *>(d);

    gboolean value = true; // "show-preroll-frame" property is true by default
    g_object_get(G_OBJECT(sink), "show-preroll-frame", &value, NULL);

    GstBuffer *buffer = sink->delegate->lastPrerolledBuffer();
    // Render the stored prerolled buffer if requested.
    // e.g. player is in stopped mode, then seek operation is requested,
    // surface now stores a prerolled frame, but doesn't display it until
    // "show-preroll-frame" property is set to "true"
    // when switching to pause or playing state.
    if (value && buffer) {
        sink->delegate->render(buffer);
        sink->delegate->setLastPrerolledBuffer(0);
    }
}

GstFlowReturn QVideoSurfaceGstSink::buffer_alloc(
        GstBaseSink *base, guint64 offset, guint size, GstCaps *caps, GstBuffer **buffer)
{
    VO_SINK(base);

    Q_UNUSED(offset);
    Q_UNUSED(size);

    if (!buffer)
        return GST_FLOW_ERROR;

    *buffer = NULL;

    if (!sink->delegate->pool())
        return GST_FLOW_OK;

    QMutexLocker poolLock(sink->delegate->poolMutex());
    QGstBufferPoolInterface *pool = sink->delegate->pool();

    if (!pool)
        return GST_FLOW_OK;

    if (sink->lastRequestedCaps && gst_caps_is_equal(sink->lastRequestedCaps, caps)) {
        //qDebug() << "reusing last caps";
        *buffer = GST_BUFFER(pool->takeBuffer(*sink->lastSurfaceFormat, sink->lastBufferCaps));
        return GST_FLOW_OK;
    }

    if (sink->delegate->supportedPixelFormats(pool->handleType()).isEmpty()) {
        //qDebug() << "sink doesn't support native pool buffers, skip buffers allocation";
        return GST_FLOW_OK;
    }

    poolLock.unlock();

    GstCaps *intersection = gst_caps_intersect(get_caps(GST_BASE_SINK(sink)), caps);

    if (gst_caps_is_empty (intersection)) {
        gst_caps_unref(intersection);
        return GST_FLOW_NOT_NEGOTIATED;
    }

    if (sink->delegate->isActive()) {
        //if format was changed, restart the surface
        QVideoSurfaceFormat format = formatForCaps(intersection);
        QVideoSurfaceFormat surfaceFormat = sink->delegate->surfaceFormat();

        if (format.pixelFormat() != surfaceFormat.pixelFormat() ||
            format.frameSize() != surfaceFormat.frameSize()) {
#ifdef DEBUG_VIDEO_SURFACE_SINK
            qDebug() << "new format requested, restart video surface";
#endif
            sink->delegate->stop();
        }
    }

    if (!sink->delegate->isActive()) {
        int bytesPerLine = 0;
        QGstBufferPoolInterface *pool = sink->delegate->pool();
        QAbstractVideoBuffer::HandleType handleType =
                pool ? pool->handleType() : QAbstractVideoBuffer::NoHandle;

        QVideoSurfaceFormat format = formatForCaps(intersection, &bytesPerLine, handleType);

        if (!sink->delegate->start(format, bytesPerLine)) {
            qWarning() << "failed to start video surface";
            return GST_FLOW_NOT_NEGOTIATED;
        }
    }

    poolLock.relock();
    pool = sink->delegate->pool();

    QVideoSurfaceFormat surfaceFormat = sink->delegate->surfaceFormat();

    if (!pool->isFormatSupported(surfaceFormat)) {
        //qDebug() << "sink doesn't support native pool format, skip custom buffers allocation";
        return GST_FLOW_OK;
    }

    if (sink->lastRequestedCaps)
        gst_caps_unref(sink->lastRequestedCaps);
    sink->lastRequestedCaps = caps;
    gst_caps_ref(sink->lastRequestedCaps);

    if (sink->lastBufferCaps)
        gst_caps_unref(sink->lastBufferCaps);
    sink->lastBufferCaps = intersection;
    gst_caps_ref(sink->lastBufferCaps);

    *sink->lastSurfaceFormat = surfaceFormat;

    *buffer =  GST_BUFFER(pool->takeBuffer(surfaceFormat, intersection));

    return GST_FLOW_OK;
}

gboolean QVideoSurfaceGstSink::start(GstBaseSink *base)
{
    Q_UNUSED(base);

    return TRUE;
}

gboolean QVideoSurfaceGstSink::stop(GstBaseSink *base)
{
    VO_SINK(base);
    sink->delegate->clearPoolBuffers();

    return TRUE;
}

gboolean QVideoSurfaceGstSink::unlock(GstBaseSink *base)
{
    Q_UNUSED(base);

    return TRUE;
}

gboolean QVideoSurfaceGstSink::event(GstBaseSink *base, GstEvent *event)
{
    // discard prerolled frame
    if (event->type == GST_EVENT_FLUSH_START) {
        VO_SINK(base);
        sink->delegate->setLastPrerolledBuffer(0);
    }

    return TRUE;
}

GstFlowReturn QVideoSurfaceGstSink::preroll(GstBaseSink *base, GstBuffer *buffer)
{
    VO_SINK(base);

    gboolean value = true; // "show-preroll-frame" property is true by default
    g_object_get(G_OBJECT(base), "show-preroll-frame", &value, NULL);
    if (value) {
        sink->delegate->setLastPrerolledBuffer(0); // discard prerolled buffer
        return sink->delegate->render(buffer); // display frame
    }

    // otherwise keep a reference to the buffer to display it later
    sink->delegate->setLastPrerolledBuffer(buffer);
    return GST_FLOW_OK;
}

GstFlowReturn QVideoSurfaceGstSink::render(GstBaseSink *base, GstBuffer *buffer)
{
    VO_SINK(base);
    sink->delegate->setLastPrerolledBuffer(0); // discard prerolled buffer
    return sink->delegate->render(buffer);
}

QT_END_NAMESPACE