Pass the remaining mediaplayerbackend autotests

* Add a notification mechanism to the pipeline so
the video output knows when QMediaPlayer is in
a stopped state (using QProperty), as we want the
pipeline to be in a paused state internally, but
not get preroll frames if we're in paused externally.

* Properly emit metadataChanged() signals, and ensure
we're in GST_STATE_PAUSED before trying a seek.

Change-Id: I1cad557e648f82909a63cba8d6144df8476524f5
Reviewed-by: Doris Verria <doris.verria@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

6 files changed, 93 insertions, 22 deletions

diff --git a/src/multimedia/platform/gstreamer/common/qgst_p.h b/src/multimedia/platform/gstreamer/common/qgst_p.h
index 0f42bab41..14fd2bd46 100644
--- a/src/multimedia/platform/gstreamer/common/qgst_p.h
+++ b/src/multimedia/platform/gstreamer/common/qgst_p.h
@@ -451,6 +451,15 @@ public:
 #endif
         return change == GST_STATE_CHANGE_SUCCESS;
     }
+    bool finishStateChange()
+    {
+        auto change = gst_element_get_state(element(), nullptr, nullptr, 10000*1e6 /*nano seconds*/);
+#ifndef QT_NO_DEBUG
+        if (change != GST_STATE_CHANGE_SUCCESS && change != GST_STATE_CHANGE_NO_PREROLL)
+            qWarning() << "Could finish change state of" << name();
+#endif
+        return change == GST_STATE_CHANGE_SUCCESS;
+    }
 
     void lockState(bool locked) { gst_element_set_locked_state(element(), locked); }
     bool isStateLocked() const { return gst_element_is_locked_state(element()); }
diff --git a/src/multimedia/platform/gstreamer/common/qgstpipeline.cpp b/src/multimedia/platform/gstreamer/common/qgstpipeline.cpp
index 40aab13b2..d3f75b612 100644
--- a/src/multimedia/platform/gstreamer/common/qgstpipeline.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstpipeline.cpp
@@ -43,6 +43,7 @@
 #include <QtCore/qlist.h>
 #include <QtCore/qabstracteventdispatcher.h>
 #include <QtCore/qcoreapplication.h>
+#include <QtCore/qproperty.h>
 
 #include "qgstpipeline_p.h"
 #include "qgstreamermessage_p.h"
@@ -52,7 +53,7 @@ QT_BEGIN_NAMESPACE
 class QGstPipelinePrivate : public QObject
 {
     Q_OBJECT
-    friend class QGstreamerBusHelperPrivate;
+public:
 
     int m_ref = 0;
     guint m_tag = 0;
@@ -61,8 +62,8 @@ class QGstPipelinePrivate : public QObject
     QMutex filterMutex;
     QList<QGstreamerSyncMessageFilter*> syncFilters;
     QList<QGstreamerBusMessageFilter*> busFilters;
+    QProperty<bool> inStoppedState;
 
-public:
     QGstPipelinePrivate(GstBus* bus, QObject* parent = 0);
     ~QGstPipelinePrivate();
 
@@ -130,7 +131,8 @@ private:
 
 QGstPipelinePrivate::QGstPipelinePrivate(GstBus* bus, QObject* parent)
   : QObject(parent),
-    m_bus(bus)
+    m_bus(bus),
+    inStoppedState(true)
 {
     gst_object_ref(GST_OBJECT(bus));
 
@@ -227,6 +229,11 @@ QGstPipeline::~QGstPipeline()
     d->deref();
 }
 
+QProperty<bool> *QGstPipeline::inStoppedState()
+{
+    return &d->inStoppedState;
+}
+
 void QGstPipeline::installMessageFilter(QGstreamerSyncMessageFilter *filter)
 {
     d->installMessageFilter(filter);
diff --git a/src/multimedia/platform/gstreamer/common/qgstpipeline_p.h b/src/multimedia/platform/gstreamer/common/qgstpipeline_p.h
index f6e7a7333..e3bc4164a 100644
--- a/src/multimedia/platform/gstreamer/common/qgstpipeline_p.h
+++ b/src/multimedia/platform/gstreamer/common/qgstpipeline_p.h
@@ -85,6 +85,13 @@ public:
     QGstPipeline(GstPipeline *p);
     ~QGstPipeline();
 
+    // This is needed to help us avoid sending QVideoFrames or audio buffers to the
+    // application while we're prerolling the pipeline.
+    // QMediaPlayer is still in a stopped state, while we put the gstreamer pipeline into a
+    // Paused state so that we can get the required metadata of the stream and also have a fast
+    // transition to play.
+    QProperty<bool> *inStoppedState();
+
     void installMessageFilter(QGstreamerSyncMessageFilter *filter);
     void removeMessageFilter(QGstreamerSyncMessageFilter *filter);
     void installMessageFilter(QGstreamerBusMessageFilter *filter);
diff --git a/src/multimedia/platform/gstreamer/common/qgstreamermediaplayer.cpp b/src/multimedia/platform/gstreamer/common/qgstreamermediaplayer.cpp
index b9e16359d..7f1e5d5ce 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreamermediaplayer.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstreamermediaplayer.cpp
@@ -39,7 +39,7 @@
 
 #include <private/qgstreamermediaplayer_p.h>
 #include <private/qgstreamervideorenderer_p.h>
-#include <private/qgstreamerbushelper_p.h>
+#include <private/qgstpipeline_p.h>
 #include <private/qgstreamermetadata_p.h>
 #include <private/qgstreamerformatinfo_p.h>
 #include <private/qgstreameraudiooutput_p.h>
@@ -156,17 +156,23 @@ void QGstreamerMediaPlayer::setPlaybackRate(qreal rate)
 
 void QGstreamerMediaPlayer::setPosition(qint64 pos)
 {
-    qCDebug(qLcMediaPlayer) << Q_FUNC_INFO << pos/1000.0;
+    qint64 currentPos = playerPipeline.position()/1e6;
+    if (pos == currentPos)
+        return;
+    playerPipeline.finishStateChange();
     playerPipeline.seek(pos*1e6, m_playbackRate);
+    qCDebug(qLcMediaPlayer) << Q_FUNC_INFO << pos << playerPipeline.position()/1e6;
     if (mediaStatus() == QMediaPlayer::EndOfMedia)
         mediaStatusChanged(QMediaPlayer::LoadedMedia);
+    positionChanged(pos);
 }
 
 void QGstreamerMediaPlayer::play()
 {
-    if (m_url.isEmpty())
+    if (state() == QMediaPlayer::PlayingState || m_url.isEmpty())
         return;
 
+    *playerPipeline.inStoppedState() = false;
     if (mediaStatus() == QMediaPlayer::EndOfMedia) {
         playerPipeline.seek(0, m_playbackRate);
         updatePosition();
@@ -176,16 +182,22 @@ void QGstreamerMediaPlayer::play()
     int ret = playerPipeline.setState(GST_STATE_PLAYING);
     if (ret == GST_STATE_CHANGE_FAILURE)
         qCDebug(qLcMediaPlayer) << "Unable to set the pipeline to the playing state.";
+    if (mediaStatus() == QMediaPlayer::LoadedMedia)
+        mediaStatusChanged(QMediaPlayer::BufferedMedia);
     emit stateChanged(QMediaPlayer::PlayingState);
     positionUpdateTimer.start(100);
 }
 
 void QGstreamerMediaPlayer::pause()
 {
-    if (m_url.isEmpty())
+    if (state() == QMediaPlayer::PausedState || m_url.isEmpty())
         return;
 
     positionUpdateTimer.stop();
+    if (*playerPipeline.inStoppedState()) {
+        *playerPipeline.inStoppedState() = false;
+        playerPipeline.seek(playerPipeline.position(), m_playbackRate);
+    }
     int ret = playerPipeline.setState(GST_STATE_PAUSED);
     if (ret == GST_STATE_CHANGE_FAILURE)
         qCDebug(qLcMediaPlayer) << "Unable to set the pipeline to the paused state.";
@@ -199,12 +211,15 @@ void QGstreamerMediaPlayer::pause()
 
 void QGstreamerMediaPlayer::stop()
 {
+    if (state() == QMediaPlayer::StoppedState)
+        return;
     stopOrEOS(false);
 }
 
 void QGstreamerMediaPlayer::stopOrEOS(bool eos)
 {
     positionUpdateTimer.stop();
+    *playerPipeline.inStoppedState() = true;
     bool ret = playerPipeline.setStateSync(GST_STATE_PAUSED);
     if (!ret)
         qCDebug(qLcMediaPlayer) << "Unable to set the pipeline to the stopped state.";
@@ -517,8 +532,6 @@ void QGstreamerMediaPlayer::setMedia(const QUrl &content, QIODevice *stream)
 
     m_url = content;
     m_stream = stream;
-    m_metaData.clear();
-    m_duration = 0;
 
     if (!src.isNull())
         playerPipeline.remove(src);
@@ -528,13 +541,22 @@ void QGstreamerMediaPlayer::setMedia(const QUrl &content, QIODevice *stream)
     decoder = QGstElement();
     removeAllOutputs();
 
-    if (content.isEmpty()) {
-        stateChanged(QMediaPlayer::StoppedState);
+    if (m_duration != 0) {
+        m_duration = 0;
+        durationChanged(0);
+    }
+    stateChanged(QMediaPlayer::StoppedState);
+    if (position() != 0)
         positionChanged(0);
-        mediaStatusChanged(QMediaPlayer::NoMedia);
-        return;
+    mediaStatusChanged(QMediaPlayer::NoMedia);
+    if (!m_metaData.isEmpty()) {
+        m_metaData.clear();
+        metaDataChanged();
     }
 
+    if (content.isEmpty())
+        return;
+
     if (m_stream) {
         if (!m_appSrc)
             m_appSrc = new QGstAppSrc(this);
@@ -621,8 +643,10 @@ static QGstStructure endOfChain(const QGstStructure &s)
 void QGstreamerMediaPlayer::parseStreamsAndMetadata()
 {
     qCDebug(qLcMediaPlayer) << "============== parse topology ============";
-    if (topology.isNull())
+    if (topology.isNull()) {
+        qCDebug(qLcMediaPlayer) << "    null topology";
         return;
+    }
     auto caps = topology["caps"].toCaps();
     auto structure = caps.at(0);
     auto fileFormat = QGstreamerFormatInfo::fileFormatForCaps(structure);
@@ -641,8 +665,11 @@ void QGstreamerMediaPlayer::parseStreamsAndMetadata()
 
     auto demux = endOfChain(topology);
     auto next = demux["next"];
-    if (!next.isList())
+    if (!next.isList()) {
+        qCDebug(qLcMediaPlayer) << "    no additional streams";
+        emit metaDataChanged();
         return;
+    }
 
     // collect stream info
     int size = next.listSize();
@@ -669,13 +696,13 @@ void QGstreamerMediaPlayer::parseStreamsAndMetadata()
     }
 
     QGstPad sinkPad = inputSelector[VideoStream].getObject("active-pad");
-    if (sinkPad.isNull())
-        return;
-    bool hasTags = g_object_class_find_property (G_OBJECT_GET_CLASS (sinkPad.object()), "tags") != NULL;
+    if (!sinkPad.isNull()) {
+        bool hasTags = g_object_class_find_property (G_OBJECT_GET_CLASS (sinkPad.object()), "tags") != NULL;
 
-    GstTagList *tl = nullptr;
-    g_object_get(sinkPad.object(), "tags", &tl, nullptr);
-    qCDebug(qLcMediaPlayer) << "    tags=" << hasTags << (tl ? gst_tag_list_to_string(tl) : "(null)");
+        GstTagList *tl = nullptr;
+        g_object_get(sinkPad.object(), "tags", &tl, nullptr);
+        qCDebug(qLcMediaPlayer) << "    tags=" << hasTags << (tl ? gst_tag_list_to_string(tl) : "(null)");
+    }
 
 
     qCDebug(qLcMediaPlayer) << "============== end parse topology ============";
diff --git a/src/multimedia/platform/gstreamer/common/qgstreamervideooutput.cpp b/src/multimedia/platform/gstreamer/common/qgstreamervideooutput.cpp
index 57753f53d..f9bf9f6c2 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreamervideooutput.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstreamervideooutput.cpp
@@ -83,6 +83,12 @@ void QGstreamerVideoOutput::setVideoSink(QVideoSink *sink)
     sinkChanged();
 }
 
+void QGstreamerVideoOutput::setPipeline(const QGstPipeline &pipeline)
+{
+    gstPipeline = pipeline;
+    stoppedStateHandler = gstPipeline.inStoppedState()->onValueChanged(std::function([this]() {updatePrerollFrame();}));
+}
+
 void QGstreamerVideoOutput::setIsPreview()
 {
     // configures the queue to be fast and lightweight for camera preview
@@ -116,13 +122,24 @@ void QGstreamerVideoOutput::updateVideoSink(const QGstElement &sink)
     pad.addProbe<&QGstreamerVideoOutput::prepareVideoOutputChange>(this, GstPadProbeType(GST_PAD_PROBE_TYPE_BUFFER | GST_PAD_PROBE_TYPE_BLOCKING));
 }
 
+void QGstreamerVideoOutput::updatePrerollFrame()
+{
+    bool stopped = true;
+    if (!gstPipeline.isNull() && !*gstPipeline.inStoppedState())
+        stopped = false;
+    if (!isFakeSink)
+        videoSink.set("show-preroll-frame", !stopped);
+}
+
 void QGstreamerVideoOutput::sinkChanged()
 {
     QGstElement gstSink;
     if (m_videoWindow) {
         gstSink = m_videoWindow->gstSink();
+        isFakeSink = false;
     } else {
         gstSink = QGstElement("fakesink", "fakevideosink");
+        isFakeSink = true;
     }
     qDebug() << "sinkChanged" << gstSink.name();
     updateVideoSink(gstSink);
@@ -140,6 +157,7 @@ void QGstreamerVideoOutput::changeVideoOutput()
     videoSink.setState(GST_STATE_NULL);
     gstVideoOutput.remove(videoSink);
     videoSink = newVideoSink;
+    updatePrerollFrame();
     videoConvert.link(videoSink);
     GstEvent *event = gst_event_new_reconfigure();
     gst_element_send_event(videoSink.element(), event);
diff --git a/src/multimedia/platform/gstreamer/common/qgstreamervideooutput_p.h b/src/multimedia/platform/gstreamer/common/qgstreamervideooutput_p.h
index a8ed8960c..16ac73b78 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreamervideooutput_p.h
+++ b/src/multimedia/platform/gstreamer/common/qgstreamervideooutput_p.h
@@ -74,13 +74,14 @@ public:
 
     void setVideoSink(QVideoSink *sink);
 
-    void setPipeline(const QGstPipeline &pipeline) { gstPipeline = pipeline; }
+    void setPipeline(const QGstPipeline &pipeline);
 
     QGstElement gstElement() const { return gstVideoOutput; }
 
     void setIsPreview();
 
     void updateVideoSink(const QGstElement &sink);
+    void updatePrerollFrame();
 public slots:
     void sinkChanged();
     void changeVideoOutput();
@@ -90,6 +91,8 @@ private:
 
     QVideoSink *m_videoSink = nullptr;
     QPointer<QGstreamerVideoSink> m_videoWindow;
+    std::optional<QPropertyChangeHandler<std::function<void()>>> stoppedStateHandler;
+    bool isFakeSink = true;
 
     // Gst elements
     QGstPipeline gstPipeline;