Source/WebCore/platform/graphics/gstreamer/mse/PlaybackPipeline.cpp

/*
 * Copyright (C) 2014, 2015 Sebastian Dröge <sebastian@centricular.com>
 * Copyright (C) 2016 Metrological Group B.V.
 * Copyright (C) 2016 Igalia S.L
 *
 * 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
 * aint with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#include "config.h"
#include "PlaybackPipeline.h"

#if ENABLE(VIDEO) && USE(GSTREAMER) && ENABLE(MEDIA_SOURCE)

#include "AudioTrackPrivateGStreamer.h"
#include "GStreamerCommon.h"
#include "MediaSampleGStreamer.h"
#include "MediaSample.h"
#include "SourceBufferPrivateGStreamer.h"
#include "VideoTrackPrivateGStreamer.h"

#include <gst/app/gstappsrc.h>
#include <gst/gst.h>
#include <wtf/MainThread.h>
#include <wtf/RefCounted.h>
#include <wtf/glib/GRefPtr.h>
#include <wtf/glib/GUniquePtr.h>
#include <wtf/text/AtomicString.h>

GST_DEBUG_CATEGORY_EXTERN(webkit_mse_debug);
#define GST_CAT_DEFAULT webkit_mse_debug

static Stream* getStreamByTrackId(WebKitMediaSrc*, AtomicString);
static Stream* getStreamBySourceBufferPrivate(WebKitMediaSrc*, WebCore::SourceBufferPrivateGStreamer*);

static Stream* getStreamByTrackId(WebKitMediaSrc* source, AtomicString trackIdString)
{
    // WebKitMediaSrc should be locked at this point.
    for (Stream* stream : source->priv->streams) {
        if (stream->type != WebCore::Invalid
            && ((stream->audioTrack && stream->audioTrack->id() == trackIdString)
                || (stream->videoTrack && stream->videoTrack->id() == trackIdString) ) ) {
            return stream;
        }
    }
    return nullptr;
}

static Stream* getStreamBySourceBufferPrivate(WebKitMediaSrc* source, WebCore::SourceBufferPrivateGStreamer* sourceBufferPrivate)
{
    for (Stream* stream : source->priv->streams) {
        if (stream->sourceBuffer == sourceBufferPrivate)
            return stream;
    }
    return nullptr;
}

// FIXME: Use gst_app_src_push_sample() instead when we switch to the appropriate GStreamer version.
static GstFlowReturn pushSample(GstAppSrc* appsrc, GstSample* sample)
{
    g_return_val_if_fail(GST_IS_SAMPLE(sample), GST_FLOW_ERROR);

    GstCaps* caps = gst_sample_get_caps(sample);
    if (caps)
        gst_app_src_set_caps(appsrc, caps);
    else
        GST_WARNING_OBJECT(appsrc, "received sample without caps");

    GstBuffer* buffer = gst_sample_get_buffer(sample);
    if (UNLIKELY(!buffer)) {
        GST_WARNING_OBJECT(appsrc, "received sample without buffer");
        return GST_FLOW_OK;
    }

    // gst_app_src_push_buffer() steals the reference, we need an additional one.
    return gst_app_src_push_buffer(appsrc, gst_buffer_ref(buffer));
}

namespace WebCore {

void PlaybackPipeline::setWebKitMediaSrc(WebKitMediaSrc* webKitMediaSrc)
{
    GST_DEBUG("webKitMediaSrc=%p", webKitMediaSrc);
    m_webKitMediaSrc = webKitMediaSrc;
}

WebKitMediaSrc* PlaybackPipeline::webKitMediaSrc()
{
    return m_webKitMediaSrc.get();
}

MediaSourcePrivate::AddStatus PlaybackPipeline::addSourceBuffer(RefPtr<SourceBufferPrivateGStreamer> sourceBufferPrivate)
{
    WebKitMediaSrcPrivate* priv = m_webKitMediaSrc->priv;

    if (priv->allTracksConfigured) {
        GST_ERROR_OBJECT(m_webKitMediaSrc.get(), "Adding new source buffers after first data not supported yet");
        return MediaSourcePrivate::NotSupported;
    }

    GST_DEBUG_OBJECT(m_webKitMediaSrc.get(), "State %d", int(GST_STATE(m_webKitMediaSrc.get())));

    Stream* stream = new Stream{ };
    stream->parent = m_webKitMediaSrc.get();
    stream->appsrc = gst_element_factory_make("appsrc", nullptr);
    stream->appsrcNeedDataFlag = false;
    stream->sourceBuffer = sourceBufferPrivate.get();

    // No track has been attached yet.
    stream->type = Invalid;
    stream->parser = nullptr;
    stream->caps = nullptr;
    stream->audioTrack = nullptr;
    stream->videoTrack = nullptr;
    stream->presentationSize = WebCore::FloatSize();
    stream->lastEnqueuedTime = MediaTime::invalidTime();

    gst_app_src_set_callbacks(GST_APP_SRC(stream->appsrc), &enabledAppsrcCallbacks, stream->parent, nullptr);
    gst_app_src_set_emit_signals(GST_APP_SRC(stream->appsrc), FALSE);
    gst_app_src_set_stream_type(GST_APP_SRC(stream->appsrc), GST_APP_STREAM_TYPE_SEEKABLE);

    gst_app_src_set_max_bytes(GST_APP_SRC(stream->appsrc), 2 * WTF::MB);
    g_object_set(G_OBJECT(stream->appsrc), "block", FALSE, "min-percent", 20, "format", GST_FORMAT_TIME, nullptr);

    GST_OBJECT_LOCK(m_webKitMediaSrc.get());
    priv->streams.append(stream);
    GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());

    gst_bin_add(GST_BIN(m_webKitMediaSrc.get()), stream->appsrc);
    gst_element_sync_state_with_parent(stream->appsrc);

    return MediaSourcePrivate::Ok;
}

void PlaybackPipeline::removeSourceBuffer(RefPtr<SourceBufferPrivateGStreamer> sourceBufferPrivate)
{
    ASSERT(WTF::isMainThread());

    GST_DEBUG_OBJECT(m_webKitMediaSrc.get(), "Element removed from MediaSource");
    GST_OBJECT_LOCK(m_webKitMediaSrc.get());
    WebKitMediaSrcPrivate* priv = m_webKitMediaSrc->priv;
    Stream* stream = getStreamBySourceBufferPrivate(m_webKitMediaSrc.get(), sourceBufferPrivate.get());
    if (stream)
        priv->streams.removeFirst(stream);
    GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());

    if (stream)
        webKitMediaSrcFreeStream(m_webKitMediaSrc.get(), stream);
}

void PlaybackPipeline::attachTrack(RefPtr<SourceBufferPrivateGStreamer> sourceBufferPrivate, RefPtr<TrackPrivateBase> trackPrivate, GstCaps* caps)
{
    WebKitMediaSrc* webKitMediaSrc = m_webKitMediaSrc.get();

    GST_OBJECT_LOCK(webKitMediaSrc);
    Stream* stream = getStreamBySourceBufferPrivate(webKitMediaSrc, sourceBufferPrivate.get());
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    ASSERT(stream);

    GST_OBJECT_LOCK(webKitMediaSrc);
    unsigned padId = stream->parent->priv->numberOfPads;
    stream->parent->priv->numberOfPads++;
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    const char* mediaType = capsMediaType(caps);
    GST_DEBUG_OBJECT(webKitMediaSrc, "Configured track %s: appsrc=%s, padId=%u, mediaType=%s", trackPrivate->id().string().utf8().data(), GST_ELEMENT_NAME(stream->appsrc), padId, mediaType);

    GUniquePtr<gchar> parserBinName(g_strdup_printf("streamparser%u", padId));

    if (areEncryptedCaps(caps)) {
        GST_DEBUG("It's encrypted content, parsers are not needed before decrypting the content");
    } else if (!g_strcmp0(mediaType, "video/x-h264")) {
        GRefPtr<GstCaps> filterCaps = adoptGRef(gst_caps_new_simple("video/x-h264", "alignment", G_TYPE_STRING, "au", nullptr));
        GstElement* capsfilter = gst_element_factory_make("capsfilter", nullptr);
        g_object_set(capsfilter, "caps", filterCaps.get(), nullptr);

        stream->parser = gst_bin_new(parserBinName.get());

        GstElement* parser = gst_element_factory_make("h264parse", nullptr);
        gst_bin_add_many(GST_BIN(stream->parser), parser, capsfilter, nullptr);
        gst_element_link_pads(parser, "src", capsfilter, "sink");

        GRefPtr<GstPad> pad = adoptGRef(gst_element_get_static_pad(parser, "sink"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("sink", pad.get()));

        pad = adoptGRef(gst_element_get_static_pad(capsfilter, "src"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("src", pad.get()));
    } else if (!g_strcmp0(mediaType, "video/x-h265")) {
        GRefPtr<GstCaps> filterCaps = adoptGRef(gst_caps_new_simple("video/x-h265", "alignment", G_TYPE_STRING, "au", nullptr));
        GstElement* capsfilter = gst_element_factory_make("capsfilter", nullptr);
        g_object_set(capsfilter, "caps", filterCaps.get(), nullptr);

        stream->parser = gst_bin_new(parserBinName.get());

        GstElement* parser = gst_element_factory_make("h265parse", nullptr);
        gst_bin_add_many(GST_BIN(stream->parser), parser, capsfilter, nullptr);
        gst_element_link_pads(parser, "src", capsfilter, "sink");

        GRefPtr<GstPad> pad = adoptGRef(gst_element_get_static_pad(parser, "sink"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("sink", pad.get()));

        pad = adoptGRef(gst_element_get_static_pad(capsfilter, "src"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("src", pad.get()));
    } else if (!g_strcmp0(mediaType, "audio/mpeg")) {
        gint mpegversion = -1;
        GstStructure* structure = gst_caps_get_structure(caps, 0);
        gst_structure_get_int(structure, "mpegversion", &mpegversion);

        GstElement* parser = nullptr;
        if (mpegversion == 1)
            parser = gst_element_factory_make("mpegaudioparse", nullptr);
        else if (mpegversion == 2 || mpegversion == 4)
            parser = gst_element_factory_make("aacparse", nullptr);
        else
            ASSERT_NOT_REACHED();

        stream->parser = gst_bin_new(parserBinName.get());
        gst_bin_add(GST_BIN(stream->parser), parser);

        GRefPtr<GstPad> pad = adoptGRef(gst_element_get_static_pad(parser, "sink"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("sink", pad.get()));

        pad = adoptGRef(gst_element_get_static_pad(parser, "src"));
        gst_element_add_pad(stream->parser, gst_ghost_pad_new("src", pad.get()));
    } else if (!g_strcmp0(mediaType, "video/x-vp8")
        || !g_strcmp0(mediaType, "video/x-vp9")
        || !g_strcmp0(mediaType, "audio/x-opus")
        || !g_strcmp0(mediaType, "audio/x-vorbis"))
        stream->parser = nullptr;
    else {
        GST_ERROR_OBJECT(stream->parent, "Unsupported media format: %s", mediaType);
        return;
    }

    GST_OBJECT_LOCK(webKitMediaSrc);
    stream->type = Unknown;
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    GRefPtr<GstPad> sourcePad;
    if (stream->parser) {
        gst_bin_add(GST_BIN(stream->parent), stream->parser);
        gst_element_sync_state_with_parent(stream->parser);

        GRefPtr<GstPad> sinkPad = adoptGRef(gst_element_get_static_pad(stream->parser, "sink"));
        sourcePad = adoptGRef(gst_element_get_static_pad(stream->appsrc, "src"));
        gst_pad_link(sourcePad.get(), sinkPad.get());
        sourcePad = adoptGRef(gst_element_get_static_pad(stream->parser, "src"));
    } else {
        GST_DEBUG_OBJECT(m_webKitMediaSrc.get(), "Stream of type %s doesn't require a parser bin", mediaType);
        sourcePad = adoptGRef(gst_element_get_static_pad(stream->appsrc, "src"));
    }
    ASSERT(sourcePad);

    // FIXME: Is padId the best way to identify the Stream? What about trackId?
    g_object_set_data(G_OBJECT(sourcePad.get()), "padId", GINT_TO_POINTER(padId));
    webKitMediaSrcLinkParser(sourcePad.get(), caps, stream);

    ASSERT(stream->parent->priv->mediaPlayerPrivate);
    int signal = -1;

    GST_OBJECT_LOCK(webKitMediaSrc);
    if (doCapsHaveType(caps, GST_AUDIO_CAPS_TYPE_PREFIX)) {
        stream->type = Audio;
        stream->parent->priv->numberOfAudioStreams++;
        signal = SIGNAL_AUDIO_CHANGED;
        stream->audioTrack = RefPtr<WebCore::AudioTrackPrivateGStreamer>(static_cast<WebCore::AudioTrackPrivateGStreamer*>(trackPrivate.get()));
    } else if (doCapsHaveType(caps, GST_VIDEO_CAPS_TYPE_PREFIX)) {
        stream->type = Video;
        stream->parent->priv->numberOfVideoStreams++;
        signal = SIGNAL_VIDEO_CHANGED;
        stream->videoTrack = RefPtr<WebCore::VideoTrackPrivateGStreamer>(static_cast<WebCore::VideoTrackPrivateGStreamer*>(trackPrivate.get()));
    } else if (doCapsHaveType(caps, GST_TEXT_CAPS_TYPE_PREFIX)) {
        stream->type = Text;
        stream->parent->priv->numberOfTextStreams++;
        signal = SIGNAL_TEXT_CHANGED;

        // FIXME: Support text tracks.
    }
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    if (signal != -1)
        g_signal_emit(G_OBJECT(stream->parent), webKitMediaSrcSignals[signal], 0, nullptr);
}

void PlaybackPipeline::reattachTrack(RefPtr<SourceBufferPrivateGStreamer> sourceBufferPrivate, RefPtr<TrackPrivateBase> trackPrivate, GstCaps* caps)
{
    GST_DEBUG("Re-attaching track");

    // FIXME: Maybe remove this method. Now the caps change is managed by gst_appsrc_push_sample() in enqueueSample()
    // and flushAndEnqueueNonDisplayingSamples().

    WebKitMediaSrc* webKitMediaSrc = m_webKitMediaSrc.get();

    GST_OBJECT_LOCK(webKitMediaSrc);
    Stream* stream = getStreamBySourceBufferPrivate(webKitMediaSrc, sourceBufferPrivate.get());
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    ASSERT(stream && stream->type != Invalid);

    int signal = -1;

    GST_OBJECT_LOCK(webKitMediaSrc);
    if (doCapsHaveType(caps, GST_AUDIO_CAPS_TYPE_PREFIX)) {
        ASSERT(stream->type == Audio);
        signal = SIGNAL_AUDIO_CHANGED;
        stream->audioTrack = RefPtr<WebCore::AudioTrackPrivateGStreamer>(static_cast<WebCore::AudioTrackPrivateGStreamer*>(trackPrivate.get()));
    } else if (doCapsHaveType(caps, GST_VIDEO_CAPS_TYPE_PREFIX)) {
        ASSERT(stream->type == Video);
        signal = SIGNAL_VIDEO_CHANGED;
        stream->videoTrack = RefPtr<WebCore::VideoTrackPrivateGStreamer>(static_cast<WebCore::VideoTrackPrivateGStreamer*>(trackPrivate.get()));
    } else if (doCapsHaveType(caps, GST_TEXT_CAPS_TYPE_PREFIX)) {
        ASSERT(stream->type == Text);
        signal = SIGNAL_TEXT_CHANGED;

        // FIXME: Support text tracks.
    }
    GST_OBJECT_UNLOCK(webKitMediaSrc);

    if (signal != -1)
        g_signal_emit(G_OBJECT(stream->parent), webKitMediaSrcSignals[signal], 0, nullptr);
}

void PlaybackPipeline::notifyDurationChanged()
{
    gst_element_post_message(GST_ELEMENT(m_webKitMediaSrc.get()), gst_message_new_duration_changed(GST_OBJECT(m_webKitMediaSrc.get())));
    // WebKitMediaSrc will ask MediaPlayerPrivateGStreamerMSE for the new duration later, when somebody asks for it.
}

void PlaybackPipeline::markEndOfStream(MediaSourcePrivate::EndOfStreamStatus)
{
    WebKitMediaSrcPrivate* priv = m_webKitMediaSrc->priv;

    GST_DEBUG_OBJECT(m_webKitMediaSrc.get(), "Have EOS");

    GST_OBJECT_LOCK(m_webKitMediaSrc.get());
    bool allTracksConfigured = priv->allTracksConfigured;
    if (!allTracksConfigured)
        priv->allTracksConfigured = true;
    GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());

    if (!allTracksConfigured) {
        gst_element_no_more_pads(GST_ELEMENT(m_webKitMediaSrc.get()));
        webKitMediaSrcDoAsyncDone(m_webKitMediaSrc.get());
    }

    Vector<GstAppSrc*> appsrcs;

    GST_OBJECT_LOCK(m_webKitMediaSrc.get());
    for (Stream* stream : priv->streams) {
        if (stream->appsrc)
            appsrcs.append(GST_APP_SRC(stream->appsrc));
    }
    GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());

    for (GstAppSrc* appsrc : appsrcs)
        gst_app_src_end_of_stream(appsrc);
}

GstPadProbeReturn segmentFixerProbe(GstPad*, GstPadProbeInfo* info, gpointer)
{
    GstEvent* event = GST_EVENT(info->data);

    if (GST_EVENT_TYPE(event) != GST_EVENT_SEGMENT)
        return GST_PAD_PROBE_OK;

    GstSegment* segment = nullptr;
    gst_event_parse_segment(event, const_cast<const GstSegment**>(&segment));

    GST_TRACE("Fixed segment base time from %" GST_TIME_FORMAT " to %" GST_TIME_FORMAT,
        GST_TIME_ARGS(segment->base), GST_TIME_ARGS(segment->start));

    segment->base = segment->start;
    segment->flags = static_cast<GstSegmentFlags>(0);

    return GST_PAD_PROBE_REMOVE;
}

void PlaybackPipeline::flush(AtomicString trackId)
{
    ASSERT(WTF::isMainThread());

    GST_DEBUG("flush: trackId=%s", trackId.string().utf8().data());

    GST_OBJECT_LOCK(m_webKitMediaSrc.get());
    Stream* stream = getStreamByTrackId(m_webKitMediaSrc.get(), trackId);

    if (!stream) {
        GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());
        return;
    }

    stream->lastEnqueuedTime = MediaTime::invalidTime();
    GstElement* appsrc = stream->appsrc;
    GST_OBJECT_UNLOCK(m_webKitMediaSrc.get());

    if (!appsrc)
        return;

    gint64 position = GST_CLOCK_TIME_NONE;
    GRefPtr<GstQuery> query = adoptGRef(gst_query_new_position(GST_FORMAT_TIME));
    if (gst_element_query(pipeline(), query.get()))
        gst_query_parse_position(query.get(), 0, &position);

    GST_TRACE("Position: %" GST_TIME_FORMAT, GST_TIME_ARGS(position));

    if (static_cast<guint64>(position) == GST_CLOCK_TIME_NONE) {
        GST_TRACE("Can't determine position, avoiding flush");
        return;
    }

    double rate;
    GstFormat format;
    gint64 start = GST_CLOCK_TIME_NONE;
    gint64 stop = GST_CLOCK_TIME_NONE;

    query = adoptGRef(gst_query_new_segment(GST_FORMAT_TIME));
    if (gst_element_query(pipeline(), query.get()))
        gst_query_parse_segment(query.get(), &rate, &format, &start, &stop);

    GST_TRACE("segment: [%" GST_TIME_FORMAT ", %" GST_TIME_FORMAT "], rate: %f",
        GST_TIME_ARGS(start), GST_TIME_ARGS(stop), rate);

    if (!gst_element_send_event(GST_ELEMENT(appsrc), gst_event_new_flush_start())) {
        GST_WARNING("Failed to send flush-start event for trackId=%s", trackId.string().utf8().data());
        return;
    }

    if (!gst_element_send_event(GST_ELEMENT(appsrc), gst_event_new_flush_stop(false))) {
        GST_WARNING("Failed to send flush-stop event for trackId=%s", trackId.string().utf8().data());
        return;
    }

    if (static_cast<guint64>(position) == GST_CLOCK_TIME_NONE || static_cast<guint64>(start) == GST_CLOCK_TIME_NONE)
        return;

    GUniquePtr<GstSegment> segment(gst_segment_new());
    gst_segment_init(segment.get(), GST_FORMAT_TIME);
    gst_segment_do_seek(segment.get(), rate, GST_FORMAT_TIME, GST_SEEK_FLAG_NONE,
        GST_SEEK_TYPE_SET, position, GST_SEEK_TYPE_SET, stop, nullptr);

    GRefPtr<GstPad> sinkPad = adoptGRef(gst_element_get_static_pad(appsrc, "src"));
    GRefPtr<GstPad> srcPad = sinkPad ? adoptGRef(gst_pad_get_peer(sinkPad.get())) : nullptr;
    if (srcPad)
        gst_pad_add_probe(srcPad.get(), GST_PAD_PROBE_TYPE_EVENT_DOWNSTREAM, segmentFixerProbe, nullptr, nullptr);

    GST_TRACE("Sending new seamless segment: [%" GST_TIME_FORMAT ", %" GST_TIME_FORMAT "], rate: %f",
        GST_TIME_ARGS(segment->start), GST_TIME_ARGS(segment->stop), segment->rate);

    if (!gst_base_src_new_seamless_segment(GST_BASE_SRC(appsrc), segment->start, segment->stop, segment->start)) {
        GST_WARNING("Failed to send seamless segment event for trackId=%s", trackId.string().utf8().data());
        return;
    }

    GST_DEBUG("trackId=%s flushed", trackId.string().utf8().data());
}

void PlaybackPipeline::enqueueSample(Ref<MediaSample>&& mediaSample)
{
    ASSERT(WTF::isMainThread());

    AtomicString trackId = mediaSample->trackID();

    GST_TRACE("enqueing sample trackId=%s PTS=%f presentationSize=%.0fx%.0f at %" GST_TIME_FORMAT " duration: %" GST_TIME_FORMAT,
        trackId.string().utf8().data(), mediaSample->presentationTime().toFloat(),
        mediaSample->presentationSize().width(), mediaSample->presentationSize().height(),
        GST_TIME_ARGS(WebCore::toGstClockTime(mediaSample->presentationTime())),
        GST_TIME_ARGS(WebCore::toGstClockTime(mediaSample->duration())));

    // No need to lock to access the Stream here because the only chance of conflict with this read and with the usage
    // of the sample fields done in this method would be the deletion of the stream. However, that operation can only
    // happen in the main thread, but we're already there. Therefore there's no conflict and locking would only cause
    // a performance penalty on the readers working in other threads.
    Stream* stream = getStreamByTrackId(m_webKitMediaSrc.get(), trackId);

    if (!stream) {
        GST_WARNING("No stream!");
        return;
    }

    if (!stream->sourceBuffer->isReadyForMoreSamples(trackId)) {
        GST_DEBUG("enqueueSample: skip adding new sample for trackId=%s, SB is not ready yet", trackId.string().utf8().data());
        return;
    }

    // This field doesn't change after creation, no need to lock.
    GstElement* appsrc = stream->appsrc;

    // Only modified by the main thread, no need to lock.
    MediaTime lastEnqueuedTime = stream->lastEnqueuedTime;

    ASSERT(mediaSample->platformSample().type == PlatformSample::GStreamerSampleType);
    GRefPtr<GstSample> gstSample = mediaSample->platformSample().sample.gstSample;
    if (gstSample && gst_sample_get_buffer(gstSample.get())) {
        GstBuffer* buffer = gst_sample_get_buffer(gstSample.get());
        lastEnqueuedTime = mediaSample->presentationTime();

        GST_BUFFER_FLAG_UNSET(buffer, GST_BUFFER_FLAG_DECODE_ONLY);
        pushSample(GST_APP_SRC(appsrc), gstSample.get());
        // gst_app_src_push_sample() uses transfer-none for gstSample.

        stream->lastEnqueuedTime = lastEnqueuedTime;
    }
}

void PlaybackPipeline::allSamplesInTrackEnqueued(const AtomicString& trackId)
{
    Stream* stream = getStreamByTrackId(m_webKitMediaSrc.get(), trackId);
    gst_app_src_end_of_stream(GST_APP_SRC(stream->appsrc));
}

GstElement* PlaybackPipeline::pipeline()
{
    if (!m_webKitMediaSrc || !GST_ELEMENT_PARENT(GST_ELEMENT(m_webKitMediaSrc.get())))
        return nullptr;

    return GST_ELEMENT_PARENT(GST_ELEMENT_PARENT(GST_ELEMENT(m_webKitMediaSrc.get())));
}

} // namespace WebCore.

#endif // USE(GSTREAMER)