GStreamer: enable dynamic pipeline modification for capture session

Work in progress...

Change-Id: I4423745a9d229e509aa161cd6a0a28647f5579e9
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

13 files changed, 331 insertions, 275 deletions

diff --git a/src/multimedia/platform/gstreamer/common/qgst_p.h b/src/multimedia/platform/gstreamer/common/qgst_p.h
index 12eb123c0..0130ca00f 100644
--- a/src/multimedia/platform/gstreamer/common/qgst_p.h
+++ b/src/multimedia/platform/gstreamer/common/qgst_p.h
@@ -53,6 +53,7 @@
 
 #include <private/qtmultimediaglobal_p.h>
 
+#include <QSemaphore>
 #include <QtCore/qlist.h>
 
 #include <QtMultimedia/qaudioformat.h>
@@ -61,6 +62,8 @@
 #include <gst/gst.h>
 #include <gst/video/video-info.h>
 
+#include <functional>
+
 #if QT_CONFIG(gstreamer_photography)
 #define GST_USE_UNSTABLE_API
 #include <gst/interfaces/photography.h>
@@ -391,6 +394,24 @@ public:
         gst_pad_add_probe (pad(), type, Impl::callback, instance, nullptr);
     }
 
+    void doInIdleProbe(std::function<void()> work) {
+        struct CallbackData {
+            QSemaphore waitDone;
+            std::function<void()> work;
+        } cd;
+        cd.work = work;
+
+        auto callback= [](GstPad *, GstPadProbeInfo *, gpointer p) {
+            auto cd = reinterpret_cast<CallbackData*>(p);
+            cd->work();
+            cd->waitDone.release();
+            return GST_PAD_PROBE_REMOVE;
+        };
+
+        gst_pad_add_probe(pad(), GST_PAD_PROBE_TYPE_IDLE, callback, &cd, nullptr);
+        cd.waitDone.acquire();
+    }
+
     template<auto Member, typename T>
     void addEosProbe(T *instance) {
         struct Impl {
@@ -455,6 +476,8 @@ public:
     { gst_element_unlink(element(), next.element()); }
 
     QGstPad staticPad(const char *name) const { return QGstPad(gst_element_get_static_pad(element(), name), HasRef); }
+    QGstPad src() const { return staticPad("src"); }
+    QGstPad sink() const { return staticPad("sink"); }
     QGstPad getRequestPad(const char *name) const { return QGstPad(gst_element_get_request_pad(element(), name), HasRef); }
     void releaseRequestPad(const QGstPad &pad) const { return gst_element_release_request_pad(element(), pad.pad()); }
 
diff --git a/src/multimedia/platform/gstreamer/common/qgstreameraudioinput.cpp b/src/multimedia/platform/gstreamer/common/qgstreameraudioinput.cpp
index 2249b8b34..cd1233c1d 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreameraudioinput.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstreameraudioinput.cpp
@@ -100,11 +100,6 @@ void QGstreamerAudioInput::setMuted(bool muted)
     emit mutedChanged(muted);
 }
 
-void QGstreamerAudioInput::setPipeline(const QGstPipeline &pipeline)
-{
-    gstPipeline = pipeline;
-}
-
 void QGstreamerAudioInput::setAudioDevice(const QAudioDevice &device)
 {
     if (device == m_audioDevice)
@@ -112,24 +107,24 @@ void QGstreamerAudioInput::setAudioDevice(const QAudioDevice &device)
     qCDebug(qLcMediaAudioInput) << "setAudioInput" << device.description() << device.isNull();
     m_audioDevice = device;
 
-    gstPipeline.beginConfig();
-
     QGstElement newSrc;
     auto *deviceInfo = static_cast<const QGStreamerAudioDeviceInfo *>(m_audioDevice.handle());
     if (deviceInfo && deviceInfo->gstDevice)
-        newSrc = gst_device_create_element(deviceInfo->gstDevice , "audiosrc");
+        newSrc = gst_device_create_element(deviceInfo->gstDevice, "audiosrc");
 
     if (newSrc.isNull())
         newSrc = QGstElement("autoaudiosrc", "audiosrc");
 
+    // FIXME: most probably source can be disconnected outside of idle probe
+    audioSrc.staticPad("src").doInIdleProbe([&](){
+        audioSrc.unlink(audioVolume);
+    });
     audioSrc.setStateSync(GST_STATE_NULL);
     gstAudioInput.remove(audioSrc);
     audioSrc = newSrc;
     gstAudioInput.add(audioSrc);
     audioSrc.link(audioVolume);
     audioSrc.syncStateWithParent();
-
-    gstPipeline.endConfig();
 }
 
 QAudioDevice QGstreamerAudioInput::audioInput() const
diff --git a/src/multimedia/platform/gstreamer/common/qgstreameraudioinput_p.h b/src/multimedia/platform/gstreamer/common/qgstreameraudioinput_p.h
index b45f96b6c..a0e7d96ab 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreameraudioinput_p.h
+++ b/src/multimedia/platform/gstreamer/common/qgstreameraudioinput_p.h
@@ -83,8 +83,6 @@ public:
     void setVolume(float volume) override;
     void setMuted(bool muted) override;
 
-    void setPipeline(const QGstPipeline &pipeline);
-
     QGstElement gstElement() const { return gstAudioInput; }
 
 Q_SIGNALS:
@@ -98,7 +96,6 @@ private:
     QAudioDevice m_audioDevice;
 
     // Gst elements
-    QGstPipeline gstPipeline;
     QGstBin gstAudioInput;
 
     QGstElement audioSrc;
diff --git a/src/multimedia/platform/gstreamer/common/qgstreameraudiooutput.cpp b/src/multimedia/platform/gstreamer/common/qgstreameraudiooutput.cpp
index 5b7235735..6338c1ee0 100644
--- a/src/multimedia/platform/gstreamer/common/qgstreameraudiooutput.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstreameraudiooutput.cpp
@@ -97,11 +97,6 @@ void QGstreamerAudioOutput::setAudioDevice(const QAudioDevice &info)
     qCDebug(qLcMediaAudioOutput) << "setAudioOutput" << info.description() << info.isNull();
     m_audioOutput = info;
 
-    gstPipeline.beginConfig();
-
-    audioSink.setStateSync(GST_STATE_NULL);
-    gstAudioOutput.remove(audioSink);
-
     QGstElement newSink;
     auto *deviceInfo = static_cast<const QGStreamerAudioDeviceInfo *>(m_audioOutput.handle());
     if (deviceInfo && deviceInfo->gstDevice)
@@ -110,12 +105,16 @@ void QGstreamerAudioOutput::setAudioDevice(const QAudioDevice &info)
     if (newSink.isNull())
         newSink = QGstElement("autoaudiosink", "audiosink");
 
-    audioSink = newSink;
-    gstAudioOutput.add(audioSink);
-    audioVolume.link(audioSink);
-    audioSink.syncStateWithParent();
+    audioVolume.staticPad("src").doInIdleProbe([&](){
+        audioVolume.unlink(audioSink);
+        gstAudioOutput.remove(audioSink);
+        gstAudioOutput.add(newSink);
+        newSink.syncStateWithParent();
+        audioVolume.link(newSink);
+    });
 
-    gstPipeline.endConfig();
+    audioSink.setStateSync(GST_STATE_NULL);
+    audioSink = newSink;
 }
 
 QT_END_NAMESPACE
diff --git a/src/multimedia/platform/gstreamer/common/qgstvideobuffer.cpp b/src/multimedia/platform/gstreamer/common/qgstvideobuffer.cpp
index b93cb9eac..878b4d410 100644
--- a/src/multimedia/platform/gstreamer/common/qgstvideobuffer.cpp
+++ b/src/multimedia/platform/gstreamer/common/qgstvideobuffer.cpp
@@ -88,16 +88,18 @@ QT_BEGIN_NAMESPACE
 QGstVideoBuffer::QGstVideoBuffer(GstBuffer *buffer, const GstVideoInfo &info, QGstreamerVideoSink *sink,
                                  const QVideoFrameFormat &frameFormat,
                                  QGstCaps::MemoryFormat format)
-    : QAbstractVideoBuffer((sink->rhi() && format != QGstCaps::CpuMemory) ?
-                            QVideoFrame::RhiTextureHandle : QVideoFrame::NoHandle, sink->rhi())
+    : QAbstractVideoBuffer((sink && sink->rhi() && format != QGstCaps::CpuMemory) ?
+                            QVideoFrame::RhiTextureHandle : QVideoFrame::NoHandle, sink ? sink->rhi() : nullptr)
     , memoryFormat(format)
     , m_frameFormat(frameFormat)
     , m_videoInfo(info)
     , m_buffer(buffer)
 {
     gst_buffer_ref(m_buffer);
-    eglDisplay = sink->eglDisplay();
-    eglImageTargetTexture2D = sink->eglImageTargetTexture2D();
+    if (sink) {
+        eglDisplay =  sink->eglDisplay();
+        eglImageTargetTexture2D = sink->eglImageTargetTexture2D();
+    }
 }
 
 QGstVideoBuffer::~QGstVideoBuffer()
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera.cpp b/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera.cpp
index b5ca6c881..1ee0244ef 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera.cpp
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera.cpp
@@ -53,16 +53,16 @@
 #include <QtCore/qdebug.h>
 
 QGstreamerCamera::QGstreamerCamera(QCamera *camera)
-    : QPlatformCamera(camera),
-      gstCameraBin("camerabin")
+        : QPlatformCamera(camera)
 {
     gstCamera = QGstElement("videotestsrc");
+    gstCapsFilter = QGstElement("capsfilter", "videoCapsFilter");
     gstDecode = QGstElement("identity");
     gstVideoConvert = QGstElement("videoconvert", "videoConvert");
     gstVideoScale = QGstElement("videoscale", "videoScale");
-    gstCameraBin.add(gstCamera, gstDecode, gstVideoConvert, gstVideoScale);
-    gstCamera.link(gstDecode, gstVideoConvert, gstVideoScale);
-
+    gstCameraBin = QGstBin("camerabin");
+    gstCameraBin.add(gstCamera, gstCapsFilter, gstDecode, gstVideoConvert, gstVideoScale);
+    gstCamera.link(gstCapsFilter, gstDecode, gstVideoConvert, gstVideoScale);
     gstCameraBin.addGhostPad(gstVideoScale, "src");
 }
 
@@ -97,88 +97,94 @@ void QGstreamerCamera::setCamera(const QCameraDevice &camera)
 {
     if (m_cameraDevice == camera)
         return;
-//    qDebug() << "setCamera" << camera;
+    qDebug() << "setCamera" << camera;
 
     m_cameraDevice = camera;
 
-    gstPipeline.beginConfig();
-
-    Q_ASSERT(!gstCamera.isNull());
-
-    gstCamera.setStateSync(GST_STATE_NULL);
-    gstCameraBin.remove(gstCamera);
-
+    QGstElement gstNewCamera;
     if (camera.isNull()) {
-        gstCamera = QGstElement("videotestsrc");
+        gstNewCamera = QGstElement("videotestsrc");
     } else {
         auto *devices = static_cast<QGstreamerMediaDevices *>(QGstreamerIntegration::instance()->devices());
         auto *device = devices->videoDevice(camera.id());
-        gstCamera = gst_device_create_element(device, "camerasrc");
+        gstNewCamera = gst_device_create_element(device, "camerasrc");
         QGstStructure properties = gst_device_get_properties(device);
         if (properties.name() == "v4l2deviceprovider")
             m_v4l2Device = QString::fromUtf8(properties["device.path"].toString());
     }
 
-    gstCameraBin.add(gstCamera);
-    // set the camera up with a decent format
-    setCameraFormatInternal({});
+    QCameraFormat f = findBestCameraFormat(camera);
+    auto caps = QGstMutableCaps::fromCameraFormat(f);
+    auto gstNewDecode = QGstElement(f.pixelFormat() == QVideoFrameFormat::Format_Jpeg ? "jpegdec" : "identity");
+
+    gstCamera.setStateSync(GST_STATE_NULL);
+    gstDecode.setStateSync(GST_STATE_NULL);
 
-    gstCamera.setState(GST_STATE_PAUSED);
+    gstCamera.unlink(gstCapsFilter);
+    gstCapsFilter.unlink(gstDecode);
+    gstDecode.unlink(gstVideoConvert);
 
-    gstPipeline.endConfig();
-    gstPipeline.dumpGraph("setCamera");
+    gstCameraBin.remove(gstCamera);
+    gstCameraBin.remove(gstDecode);
+
+    gstCapsFilter.set("caps", caps);
+
+    gstCameraBin.add(gstNewCamera, gstNewDecode);
+
+    gstNewDecode.link(gstVideoConvert);
+    gstCapsFilter.link(gstNewDecode);
+
+    if (!gstNewCamera.link(gstCapsFilter))
+        qWarning() << "linking camera failed" << gstCamera.name() << caps.toString();
+
+    // Start sending frames once pipeline is linked
+    // FIXME: put camera to READY state before linking to decoder as in the NULL state it does not know its true caps
+    gstCapsFilter.syncStateWithParent();
+    gstNewDecode.syncStateWithParent();
+    gstNewCamera.syncStateWithParent();
+
+    gstCamera = gstNewCamera;
+    gstDecode = gstNewDecode;
 
     updateCameraProperties();
 }
 
-void QGstreamerCamera::setCameraFormatInternal(const QCameraFormat &format)
+bool QGstreamerCamera::setCameraFormat(const QCameraFormat &format)
 {
+    if (!format.isNull() && !m_cameraDevice.videoFormats().contains(format))
+        return false;
+
+    qDebug() << "Set camera format";
+
     QCameraFormat f = format;
     if (f.isNull())
         f = findBestCameraFormat(m_cameraDevice);
 
-    // add jpeg decoder where required
-    gstDecode.setStateSync(GST_STATE_NULL);
-    gstCameraBin.remove(gstDecode);
+    auto caps = QGstMutableCaps::fromCameraFormat(f);
 
-    if (f.pixelFormat() == QVideoFrameFormat::Format_Jpeg) {
-//        qDebug() << "    enabling jpeg decoder";
-        gstDecode = QGstElement("jpegdec");
-    } else {
-//        qDebug() << "    camera delivers raw video";
-        gstDecode = QGstElement("identity");
-    }
-    gstCameraBin.add(gstDecode);
-    gstDecode.link(gstVideoConvert);
+    auto newGstDecode = QGstElement(f.pixelFormat() == QVideoFrameFormat::Format_Jpeg ? "jpegdec" : "identity");
+    gstCameraBin.add(newGstDecode);
+    newGstDecode.syncStateWithParent();
 
-    auto caps = QGstMutableCaps::fromCameraFormat(f);
-    if (!caps.isNull()) {
-        if (!gstCamera.linkFiltered(gstDecode, caps))
-            qWarning() << "linking filtered camera to decoder failed" << gstCamera.name() << gstDecode.name() << caps.toString();
-    } else {
-        if (!gstCamera.link(gstDecode))
-            qWarning() << "linking camera to decoder failed" << gstCamera.name() << gstDecode.name();
-    }
-}
+    gstCamera.staticPad("src").doInIdleProbe([&](){
+        gstCamera.unlink(gstCapsFilter);
+        gstCapsFilter.unlink(gstDecode);
+        gstDecode.unlink(gstVideoConvert);
 
-bool QGstreamerCamera::setCameraFormat(const QCameraFormat &format)
-{
-    if (!format.isNull() && !m_cameraDevice.videoFormats().contains(format))
-        return false;
-    gstPipeline.beginConfig();
-    setCameraFormatInternal(format);
-    gstPipeline.endConfig();
-    return true;
-}
+        gstCapsFilter.set("caps", caps);
 
-void QGstreamerCamera::setCaptureSession(QPlatformMediaCaptureSession *session)
-{
-    QGstreamerMediaCapture *captureSession = static_cast<QGstreamerMediaCapture *>(session);
-    if (m_session == captureSession)
-        return;
+        newGstDecode.link(gstVideoConvert);
+        gstCapsFilter.link(newGstDecode);
+        if (!gstCamera.link(gstCapsFilter))
+            qWarning() << "linking filtered camera to decoder failed" << gstCamera.name() << caps.toString();
+    });
 
-    m_session = captureSession;
-    gstPipeline = m_session ? m_session->pipeline() : QGstPipeline();
+    gstDecode.setStateSync(GST_STATE_NULL);
+    gstCameraBin.remove(gstDecode);
+
+    gstDecode = newGstDecode;
+
+    return true;
 }
 
 void QGstreamerCamera::updateCameraProperties()
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera_p.h b/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera_p.h
index 51037119e..94f2f8678 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera_p.h
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamercamera_p.h
@@ -71,9 +71,6 @@ public:
 
     void setCamera(const QCameraDevice &camera) override;
     bool setCameraFormat(const QCameraFormat &format) override;
-    void setCameraFormatInternal(const QCameraFormat &format);
-
-    void setCaptureSession(QPlatformMediaCaptureSession *session) override;
 
     QGstElement gstElement() const { return gstCameraBin.element(); }
 #if QT_CONFIG(gstreamer_photography)
@@ -123,14 +120,11 @@ private:
     int v4l2FileDescriptor = -1;
 #endif
 
-    QGstreamerMediaCapture *m_session = nullptr;
-
     QCameraDevice m_cameraDevice;
 
-    QGstPipeline gstPipeline;
-
     QGstBin gstCameraBin;
     QGstElement gstCamera;
+    QGstElement gstCapsFilter;
     QGstElement gstDecode;
     QGstElement gstVideoConvert;
     QGstElement gstVideoScale;
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture.cpp b/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture.cpp
index f4434e549..2d943def2 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture.cpp
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture.cpp
@@ -74,10 +74,13 @@ QGstreamerImageCapture::QGstreamerImageCapture(QImageCapture *parent)
     encoder = QGstElement("jpegenc", "jpegEncoder");
     muxer = QGstElement("jifmux", "jpegMuxer");
     sink = QGstElement("fakesink","imageCaptureSink");
+    // imageCaptureSink do not wait for a preroll buffer when going READY -> PAUSED
+    // as no buffer will arrive until capture() is called
+    sink.set("async", false);
+
     bin.add(queue, videoConvert, encoder, muxer, sink);
     queue.link(videoConvert, encoder, muxer, sink);
     bin.addGhostPad(queue, "sink");
-    bin.lockState(true);
 
     addProbeToPad(queue.staticPad("src").pad(), false);
 
@@ -87,8 +90,7 @@ QGstreamerImageCapture::QGstreamerImageCapture(QImageCapture *parent)
 
 QGstreamerImageCapture::~QGstreamerImageCapture()
 {
-    if (m_session)
-        m_session->releaseVideoPad(videoSrcPad);
+    bin.setStateSync(GST_STATE_NULL);
 }
 
 bool QGstreamerImageCapture::isReadyForCapture() const
@@ -149,10 +151,6 @@ int QGstreamerImageCapture::doCapture(const QString &fileName)
     // let one image pass the pipeline
     passImage = true;
 
-    link();
-
-    gstPipeline.dumpGraph("captureImage");
-
     emit readyForCaptureChanged(false);
     return m_lastId;
 }
@@ -217,22 +215,12 @@ void QGstreamerImageCapture::setCaptureSession(QPlatformMediaCaptureSession *ses
         pendingImages.clear();
         passImage = false;
         cameraActive = false;
-        gstPipeline.beginConfig();
-        bin.setStateSync(GST_STATE_NULL);
-        gstPipeline.remove(bin);
-        gstPipeline.endConfig();
-        gstPipeline = {};
     }
 
     m_session = captureSession;
     if (!m_session)
         return;
 
-    gstPipeline = captureSession->pipeline();
-    gstPipeline.beginConfig();
-    gstPipeline.add(bin);
-    bin.setStateSync(GST_STATE_READY);
-    gstPipeline.endConfig();
     connect(m_session, &QPlatformMediaCaptureSession::cameraChanged, this, &QGstreamerImageCapture::onCameraChanged);
     onCameraChanged();
 }
@@ -265,14 +253,14 @@ gboolean QGstreamerImageCapture::saveImageFilter(GstElement *element,
     Q_UNUSED(pad);
     QGstreamerImageCapture *capture = static_cast<QGstreamerImageCapture *>(appdata);
 
+    capture->passImage = false;
+
     if (capture->pendingImages.isEmpty()) {
-        capture->unlink();
         return true;
     }
 
     auto imageData = capture->pendingImages.dequeue();
     if (imageData.filename.isEmpty()) {
-        capture->unlink();
         return true;
     }
 
@@ -294,41 +282,9 @@ gboolean QGstreamerImageCapture::saveImageFilter(GstElement *element,
                            Q_ARG(QString, imageData.filename));
     }
 
-    capture->unlink();
-
     return TRUE;
 }
 
-void QGstreamerImageCapture::unlink()
-{
-    return;
-    if (passImage)
-        return;
-    if (gstPipeline.isNull())
-        return;
-    gstPipeline.beginConfig();
-    videoSrcPad.unlinkPeer();
-    m_session->releaseVideoPad(videoSrcPad);
-    videoSrcPad = {};
-    bin.setStateSync(GST_STATE_READY);
-    bin.lockState(true);
-    gstPipeline.endConfig();
-}
-
-void QGstreamerImageCapture::link()
-{
-    if (!(m_session && m_session->camera()))
-        return;
-    if (!bin.staticPad("sink").peer().isNull() || gstPipeline.isNull())
-        return;
-    gstPipeline.beginConfig();
-    videoSrcPad = m_session->getVideoPad();
-    videoSrcPad.link(bin.staticPad("sink"));
-    bin.lockState(false);
-    bin.setState(GST_STATE_PAUSED);
-    gstPipeline.endConfig();
-}
-
 QImageEncoderSettings QGstreamerImageCapture::imageSettings() const
 {
     return m_settings;
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture_p.h b/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture_p.h
index 50d1d9a7b..a0f5d1a0b 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture_p.h
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamerimagecapture_p.h
@@ -68,7 +68,7 @@ class QGstreamerImageCapture : public QPlatformImageCapture, private QGstreamerB
 {
     Q_OBJECT
 public:
-    QGstreamerImageCapture(QImageCapture *parent/*, const QGstPipeline &pipeline*/);
+    QGstreamerImageCapture(QImageCapture *parent);
     virtual ~QGstreamerImageCapture();
 
     bool isReadyForCapture() const override;
@@ -91,8 +91,6 @@ public Q_SLOTS:
 private:
     int doCapture(const QString &fileName);
     static gboolean saveImageFilter(GstElement *element, GstBuffer *buffer, GstPad *pad, void *appdata);
-    void link();
-    void unlink();
 
     QGstreamerMediaCapture *m_session = nullptr;
     int m_lastId = 0;
@@ -106,7 +104,6 @@ private:
 
     QQueue<PendingImage> pendingImages;
 
-    QGstPipeline gstPipeline;
     QGstBin bin;
     QGstElement queue;
     QGstElement videoConvert;
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture.cpp b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture.cpp
index ad043ba51..478eb1c0a 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture.cpp
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture.cpp
@@ -53,6 +53,28 @@ QT_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(qLcMediaCapture, "qt.multimedia.capture")
 
+
+static void linkTeeToPad(QGstElement tee, QGstPad sink)
+{
+    if (tee.isNull() || sink.isNull())
+        return;
+
+    auto source = tee.getRequestPad("src_%u");
+    source.link(sink);
+}
+
+static void unlinkTeeFromPad(QGstElement tee, QGstPad sink)
+{
+    if (tee.isNull() || sink.isNull())
+        return;
+
+    auto source = sink.peer();
+    source.unlink(sink);
+
+    tee.releaseRequestPad(source);
+}
+
+
 QGstreamerMediaCapture::QGstreamerMediaCapture()
     : gstPipeline("pipeline")
 {
@@ -60,8 +82,48 @@ QGstreamerMediaCapture::QGstreamerMediaCapture()
     gstVideoOutput->setIsPreview();
     gstVideoOutput->setPipeline(gstPipeline);
 
+    // Use system clock to drive all elements in the pipeline. Otherwise,
+    // the clock is sourced from the elements (e.g. from an audio source).
+    // Since the elements are added and removed dynamically the clock would
+    // also change causing lost of synchronization in the pipeline.
+    gst_pipeline_use_clock(gstPipeline.pipeline(), gst_system_clock_obtain());
+
+    // This is the recording pipeline with only live sources, thus the pipeline
+    // will be always in the playing state.
     gstPipeline.setState(GST_STATE_PLAYING);
 
+    // TODO: remove this debug before final commit
+    // Four basic elements of the capture session showing the current position and state
+    // All presented position should show similar progress.
+    heartbeat.setInterval(1000);
+    heartbeat.start();
+    QObject::connect(&heartbeat, &QTimer::timeout, [this]() {
+        if (!gstPipeline.isNull()) {
+            gint64 current = -1;
+            gst_element_query_position(gstPipeline.element(),GST_FORMAT_TIME, &current);
+            qDebug() << "Pipeline  " <<  current / 1000000 << gstPipeline.state();
+//            auto name = QString::number(current).toLocal8Bit().data();
+//            gstPipeline.dumpGraph(name);
+        }
+        if (gstAudioInput && !gstAudioInput->gstElement().isNull()) {
+            gint64 current = -1;
+            auto element = gstAudioInput->gstElement().element();
+            gst_element_query_position(element,GST_FORMAT_TIME, &current);
+            qDebug() << "Audio     " <<  current / 1000000 << gstAudioInput->gstElement().state();
+        }
+        if (gstCamera && !gstCamera->gstElement().isNull()) {
+            gint64 current = -1;
+            gst_element_query_position(gstCamera->gstElement().element(),GST_FORMAT_TIME, &current);
+            qDebug() << "Camera    " <<  current / 1000000 << gstCamera->gstElement().state();
+        }
+        auto encoder = !m_mediaEncoder ? QGstElement{} : m_mediaEncoder->getEncoder();
+        if (!encoder.isNull()) {
+            gint64 current = -1;
+            gst_element_query_position(encoder.element(),GST_FORMAT_TIME, &current);
+            qDebug() << "Encoder   " <<  current / 1000000 << encoder.state();
+        }
+    });
+
     gstPipeline.dumpGraph("initial");
 }
 
@@ -84,10 +146,10 @@ void QGstreamerMediaCapture::setCamera(QPlatformCamera *camera)
     if (gstCamera == control)
         return;
 
-    gstPipeline.beginConfig();
-
     if (gstCamera) {
-        gstCamera->setCaptureSession(nullptr);
+        unlinkTeeFromPad(gstVideoTee, encoderVideoSink);
+        unlinkTeeFromPad(gstVideoTee, imageCaptureSink);
+
         auto camera = gstCamera->gstElement();
         camera.setStateSync(GST_STATE_NULL);
         gstVideoTee.setStateSync(GST_STATE_NULL);
@@ -98,26 +160,31 @@ void QGstreamerMediaCapture::setCamera(QPlatformCamera *camera)
         gstPipeline.remove(gstVideoOutput->gstElement());
 
         gstVideoTee = {};
+        gstCamera->setCaptureSession(nullptr);
     }
 
     gstCamera = control;
     if (gstCamera) {
         QGstElement camera = gstCamera->gstElement();
         gstVideoTee = QGstElement("tee", "videotee");
+        gstVideoTee.set("allow-not-linked", true);
+
+        gstPipeline.add(gstVideoOutput->gstElement(), camera, gstVideoTee);
 
-        gstPipeline.add(camera, gstVideoTee, gstVideoOutput->gstElement());
-        auto pad = gstVideoTee.getRequestPad("src_%u");
-        pad.link(gstVideoOutput->gstElement().staticPad("sink"));
-        gstCamera->gstElement().link(gstVideoTee);
-        gstCamera->setCaptureSession(this);
+        linkTeeToPad(gstVideoTee, encoderVideoSink);
+        linkTeeToPad(gstVideoTee, gstVideoOutput->gstElement().staticPad("sink"));
+        linkTeeToPad(gstVideoTee, imageCaptureSink);
 
-        camera.setState(GST_STATE_PAUSED);
+        camera.link(gstVideoTee);
+
+        gstVideoOutput->gstElement().setState(GST_STATE_PLAYING);
+        gstVideoTee.setState(GST_STATE_PLAYING);
+        camera.setState(GST_STATE_PLAYING);
     }
 
-    gstPipeline.endConfig();
+    gstPipeline.dumpGraph("camera");
 
     emit cameraChanged();
-    gstPipeline.dumpGraph("camera");
 }
 
 QPlatformImageCapture *QGstreamerMediaCapture::imageCapture()
@@ -131,16 +198,25 @@ void QGstreamerMediaCapture::setImageCapture(QPlatformImageCapture *imageCapture
     if (m_imageCapture == control)
         return;
 
-    gstPipeline.beginConfig();
-
-    if (m_imageCapture)
+    if (m_imageCapture) {
+        unlinkTeeFromPad(gstVideoTee, imageCaptureSink);
+        m_imageCapture->gstElement().setStateSync(GST_STATE_NULL);
+        gstPipeline.remove(m_imageCapture->gstElement());
+        imageCaptureSink = {};
         m_imageCapture->setCaptureSession(nullptr);
+    }
 
     m_imageCapture = control;
-    if (m_imageCapture)
+    if (m_imageCapture) {
+        imageCaptureSink = m_imageCapture->gstElement().staticPad("sink");
+        m_imageCapture->gstElement().setState(GST_STATE_PLAYING);
+        gstPipeline.add(m_imageCapture->gstElement());
+        linkTeeToPad(gstVideoTee, imageCaptureSink);
         m_imageCapture->setCaptureSession(this);
+    }
+
+    gstPipeline.dumpGraph("imageCapture");
 
-    gstPipeline.endConfig();
     emit imageCaptureChanged();
 }
 
@@ -150,16 +226,12 @@ void QGstreamerMediaCapture::setMediaEncoder(QPlatformMediaEncoder *encoder)
     if (m_mediaEncoder == control)
         return;
 
-    gstPipeline.setStateSync(GST_STATE_PAUSED);
-
     if (m_mediaEncoder)
         m_mediaEncoder->setCaptureSession(nullptr);
     m_mediaEncoder = control;
     if (m_mediaEncoder)
         m_mediaEncoder->setCaptureSession(this);
 
-    gstPipeline.setState(GST_STATE_PLAYING);
-
     emit encoderChanged();
     gstPipeline.dumpGraph("encoder");
 }
@@ -169,31 +241,82 @@ QPlatformMediaEncoder *QGstreamerMediaCapture::mediaEncoder()
     return m_mediaEncoder;
 }
 
+void QGstreamerMediaCapture::linkEncoder(QGstPad audioSink, QGstPad videoSink)
+{
+    if (!gstVideoTee.isNull() && !videoSink.isNull()) {
+        auto caps = gst_pad_get_current_caps(gstVideoTee.sink().pad());
+
+        encoderVideoCapsFilter = QGstElement("capsfilter", "encoderVideoCapsFilter");
+        encoderVideoCapsFilter.set("caps", QGstMutableCaps(caps));
+
+        gstPipeline.add(encoderVideoCapsFilter);
+
+        encoderVideoCapsFilter.src().link(videoSink);
+        linkTeeToPad(gstVideoTee, encoderVideoCapsFilter.sink());
+        encoderVideoCapsFilter.setState(GST_STATE_PLAYING);
+        encoderVideoSink = encoderVideoCapsFilter.sink();
+    }
+
+    if (!gstAudioTee.isNull() && !audioSink.isNull()) {
+        auto caps = gst_pad_get_current_caps(gstAudioTee.sink().pad());
+
+        encoderAudioCapsFilter = QGstElement("capsfilter", "encoderAudioCapsFilter");
+        encoderAudioCapsFilter.set("caps", QGstMutableCaps(caps));
+
+        gstPipeline.add(encoderAudioCapsFilter);
+
+        encoderAudioCapsFilter.src().link(audioSink);
+        linkTeeToPad(gstAudioTee, encoderAudioCapsFilter.sink());
+        encoderAudioCapsFilter.setState(GST_STATE_PLAYING);
+        encoderAudioSink = encoderAudioCapsFilter.sink();
+    }
+}
+
+void QGstreamerMediaCapture::unlinkEncoder()
+{
+    if (!encoderVideoCapsFilter.isNull()) {
+        encoderVideoCapsFilter.src().unlinkPeer();
+        unlinkTeeFromPad(gstVideoTee, encoderVideoCapsFilter.sink());
+        encoderVideoCapsFilter.setStateSync(GST_STATE_NULL);
+        gstPipeline.remove(encoderVideoCapsFilter);
+        encoderVideoCapsFilter = {};
+    }
+
+    if (!encoderAudioCapsFilter.isNull()) {
+        encoderAudioCapsFilter.src().unlinkPeer();
+        unlinkTeeFromPad(gstAudioTee, encoderAudioCapsFilter.sink());
+        encoderAudioCapsFilter.setStateSync(GST_STATE_NULL);
+        gstPipeline.remove(encoderAudioCapsFilter);
+        encoderAudioCapsFilter = {};
+    }
+
+    encoderAudioSink = {};
+    encoderVideoSink = {};
+}
+
 void QGstreamerMediaCapture::setAudioInput(QPlatformAudioInput *input)
 {
     if (gstAudioInput == input)
         return;
 
-    gstPipeline.beginConfig();
     if (gstAudioInput) {
-        gstAudioInput->gstElement().setStateSync(GST_STATE_NULL);
-        gstPipeline.remove(gstAudioInput->gstElement());
-        gstAudioInput->setPipeline({});
-        gstAudioTee.setStateSync(GST_STATE_NULL);
+        unlinkTeeFromPad(gstAudioTee, encoderAudioSink);
+
         if (gstAudioOutput) {
-            gstAudioOutputPad.unlinkPeer();
-            gstAudioTee.releaseRequestPad(gstAudioOutputPad);
-            gstAudioOutputPad = {};
+            unlinkTeeFromPad(gstAudioTee, gstAudioOutput->gstElement().staticPad("sink"));
             gstAudioOutput->gstElement().setStateSync(GST_STATE_NULL);
             gstPipeline.remove(gstAudioOutput->gstElement());
         }
+
+        gstAudioInput->gstElement().setStateSync(GST_STATE_NULL);
+        gstPipeline.remove(gstAudioInput->gstElement());
+        gstAudioTee.setStateSync(GST_STATE_NULL);
         gstPipeline.remove(gstAudioTee);
         gstAudioTee = {};
     }
 
     gstAudioInput = static_cast<QGstreamerAudioInput *>(input);
     if (gstAudioInput) {
-        gstAudioInput->setPipeline(gstPipeline);
         Q_ASSERT(gstAudioTee.isNull());
         gstAudioTee = QGstElement("tee", "audiotee");
         gstAudioTee.set("allow-not-linked", true);
@@ -202,12 +325,15 @@ void QGstreamerMediaCapture::setAudioInput(QPlatformAudioInput *input)
 
         if (gstAudioOutput) {
             gstPipeline.add(gstAudioOutput->gstElement());
-            gstAudioOutputPad = gstAudioTee.getRequestPad("src_%u");
-            gstAudioOutputPad.link(gstAudioOutput->gstElement().staticPad("sink"));
+            gstAudioOutput->gstElement().setState(GST_STATE_PLAYING);
+            linkTeeToPad(gstAudioTee, gstAudioOutput->gstElement().staticPad("sink"));
         }
-    }
 
-    gstPipeline.endConfig();
+        gstAudioTee.setState(GST_STATE_PLAYING);
+        gstAudioInput->gstElement().setStateSync(GST_STATE_PLAYING);
+
+        linkTeeToPad(gstAudioTee, encoderAudioSink);
+    }
 }
 
 void QGstreamerMediaCapture::setVideoPreview(QVideoSink *sink)
@@ -219,53 +345,20 @@ void QGstreamerMediaCapture::setAudioOutput(QPlatformAudioOutput *output)
 {
     if (gstAudioOutput == output)
         return;
-    gstPipeline.beginConfig();
 
-    if (gstAudioOutput) {
+    if (gstAudioOutput && gstAudioInput) {
+        // If audio input is set, the output is in the pipeline
+        unlinkTeeFromPad(gstAudioTee, gstAudioOutput->gstElement().staticPad("sink"));
         gstAudioOutput->gstElement().setStateSync(GST_STATE_NULL);
-        if (!gstAudioTee.isNull()) {
-            gstAudioOutputPad.unlinkPeer();
-            gstAudioTee.releaseRequestPad(gstAudioOutputPad);
-            gstAudioOutputPad = {};
-            gstPipeline.remove(gstAudioOutput->gstElement());
-        }
-        gstAudioOutput->setPipeline({});
+        gstPipeline.remove(gstAudioOutput->gstElement());
     }
 
     gstAudioOutput = static_cast<QGstreamerAudioOutput *>(output);
-    if (gstAudioOutput) {
-        gstAudioOutput->setPipeline(gstPipeline);
-        if (!gstAudioTee.isNull()) {
-            gstPipeline.add(gstAudioOutput->gstElement());
-            gstAudioOutputPad = gstAudioTee.getRequestPad("src_%u");
-            gstAudioOutputPad.link(gstAudioOutput->gstElement().staticPad("sink"));
-        }
+    if (gstAudioOutput && gstAudioInput) {
+        gstPipeline.add(gstAudioOutput->gstElement());
+        gstAudioOutput->gstElement().setState(GST_STATE_PLAYING);
+        linkTeeToPad(gstAudioTee, gstAudioOutput->gstElement().staticPad("sink"));
     }
-
-    gstPipeline.endConfig();
-}
-
-
-QGstPad QGstreamerMediaCapture::getAudioPad() const
-{
-    return gstAudioTee.isNull() ? QGstPad() : gstAudioTee.getRequestPad("src_%u");
-}
-
-QGstPad QGstreamerMediaCapture::getVideoPad() const
-{
-    return gstVideoTee.isNull() ? QGstPad() : gstVideoTee.getRequestPad("src_%u");
-}
-
-void QGstreamerMediaCapture::releaseAudioPad(const QGstPad &pad) const
-{
-    if (!pad.isNull())
-        gstAudioTee.releaseRequestPad(pad);
-}
-
-void QGstreamerMediaCapture::releaseVideoPad(const QGstPad &pad) const
-{
-    if (!pad.isNull())
-        gstVideoTee.releaseRequestPad(pad);
 }
 
 QGstreamerVideoSink *QGstreamerMediaCapture::gstreamerVideoSink() const
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture_p.h b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture_p.h
index 542f82531..ed75a27d1 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture_p.h
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediacapture_p.h
@@ -57,6 +57,8 @@
 #include <private/qgst_p.h>
 #include <private/qgstpipeline_p.h>
 
+#include <qtimer.h>
+
 QT_BEGIN_NAMESPACE
 
 class QGstreamerCamera;
@@ -85,14 +87,13 @@ public:
     void setMediaEncoder(QPlatformMediaEncoder *encoder) override;
 
     void setAudioInput(QPlatformAudioInput *input) override;
+    QGstreamerAudioInput *audioInput() { return gstAudioInput; }
 
     void setVideoPreview(QVideoSink *sink) override;
     void setAudioOutput(QPlatformAudioOutput *output) override;
 
-    QGstPad getAudioPad() const;
-    QGstPad getVideoPad() const;
-    void releaseAudioPad(const QGstPad &pad) const;
-    void releaseVideoPad(const QGstPad &pad) const;
+    void linkEncoder(QGstPad audioSink, QGstPad videoSink);
+    void unlinkEncoder();
 
     QGstPipeline pipeline() const { return gstPipeline; }
 
@@ -102,14 +103,20 @@ private:
     friend QGstreamerMediaEncoder;
     // Gst elements
     QGstPipeline gstPipeline;
+    QTimer heartbeat;
 
     QGstreamerAudioInput *gstAudioInput = nullptr;
     QGstreamerCamera *gstCamera = nullptr;
 
     QGstElement gstAudioTee;
     QGstElement gstVideoTee;
+    QGstElement encoderVideoCapsFilter;
+    QGstElement encoderAudioCapsFilter;
+
+    QGstPad encoderAudioSink;
+    QGstPad encoderVideoSink;
+    QGstPad imageCaptureSink;
 
-    QGstPad gstAudioOutputPad;
     QGstreamerAudioOutput *gstAudioOutput = nullptr;
     QGstreamerVideoOutput *gstVideoOutput = nullptr;
 
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder.cpp b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder.cpp
index 7fba45341..54caca0d6 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder.cpp
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder.cpp
@@ -42,6 +42,7 @@
 #include "private/qgstreamerformatinfo_p.h"
 #include "private/qgstpipeline_p.h"
 #include "private/qgstreamermessage_p.h"
+#include "private/qplatformcamera_p.h"
 #include "qaudiodevice.h"
 #include "qmediastoragelocation_p.h"
 
@@ -123,6 +124,7 @@ bool QGstreamerMediaEncoder::processBusMessage(const QGstreamerMessage &message)
         error(QMediaRecorder::ResourceError, QString::fromUtf8(err->message));
         g_error_free(err);
         g_free(debug);
+        finalize();
     }
 
     if (GST_MESSAGE_SRC(gm) == gstEncoder.object()) {
@@ -283,6 +285,14 @@ void QGstreamerMediaEncoder::record(QMediaEncoderSettings &settings)
     if (!m_session || state() != QMediaRecorder::StoppedState)
         return;
 
+    const auto hasVideo = m_session->camera() && m_session->camera()->isActive();
+    const auto hasAudio = m_session->audioInput() != nullptr;
+
+    if (!hasVideo && !hasAudio) {
+        error(QMediaRecorder::ResourceError, QMediaRecorder::tr("No camera or audio input"));
+        return;
+    }
+
     const auto audioOnly = settings.videoCodec() == QMediaFormat::VideoCodec::Unspecified;
 
     auto primaryLocation = audioOnly ? QStandardPaths::MusicLocation : QStandardPaths::MoviesLocation;
@@ -294,10 +304,6 @@ void QGstreamerMediaEncoder::record(QMediaEncoderSettings &settings)
 
     Q_ASSERT(!actualSink.isEmpty());
 
-    gstPipeline.dumpGraph("before-recording");
-
-    gstPipeline.beginConfig();
-
     gstEncoder = QGstElement("encodebin", "encodebin");
     auto *encodingProfile = createEncodingProfile(settings);
     g_object_set (gstEncoder.object(), "profile", encodingProfile, nullptr);
@@ -305,30 +311,33 @@ void QGstreamerMediaEncoder::record(QMediaEncoderSettings &settings)
 
     gstFileSink = QGstElement("filesink", "filesink");
     gstFileSink.set("location", QFile::encodeName(actualSink.toLocalFile()).constData());
+    gstFileSink.set("async", false);
 
-    gstPipeline.add(gstEncoder, gstFileSink);
-    gstEncoder.link(gstFileSink);
-
-    gstEncoder.setState(GST_STATE_PAUSED);
-    gstFileSink.setState(GST_STATE_PAUSED);
+    QGstPad audioSink = {};
+    QGstPad videoSink = {};
 
-    audioSrcPad = m_session->getAudioPad();
-    if (!audioSrcPad.isNull()) {
-        QGstPad audioPad = gstEncoder.getRequestPad("audio_%u");
-        audioPauseControl.installOn(audioPad);
-        audioSrcPad.link(audioPad);
+    if (hasAudio) {
+        audioSink = gstEncoder.getRequestPad("audio_%u");
+        if (audioSink.isNull())
+            qWarning() << "Unsupported audio codec";
+        else
+            audioPauseControl.installOn(audioSink);
     }
 
-    if (settings.videoCodec() != QMediaFormat::VideoCodec::Unspecified) {
-        videoSrcPad = m_session->getVideoPad();
-        if (!videoSrcPad.isNull()) {
-            QGstPad videoPad = gstEncoder.getRequestPad("video_%u");
-            videoPauseControl.installOn(videoPad);
-            videoSrcPad.link(videoPad);
-        }
+    if (hasVideo) {
+        videoSink = gstEncoder.getRequestPad("video_%u");
+        if (videoSink.isNull())
+            qWarning() << "Unsupported video codec";
+        else
+            videoPauseControl.installOn(videoSink);
     }
 
-    gstPipeline.endConfig();
+    gstPipeline.add(gstEncoder, gstFileSink);
+    gstEncoder.link(gstFileSink);
+    m_session->linkEncoder(audioSink, videoSink);
+
+    gstEncoder.syncStateWithParent();
+    gstFileSink.syncStateWithParent();
 
     m_duration.start();
     heartbeat.start();
@@ -344,8 +353,6 @@ void QGstreamerMediaEncoder::pause()
         return;
     heartbeat.stop();
     gstPipeline.dumpGraph("before-pause");
-    gstEncoder.setState(GST_STATE_PAUSED);
-
     stateChanged(QMediaRecorder::PausedState);
 }
 
@@ -355,7 +362,6 @@ void QGstreamerMediaEncoder::resume()
     if (!m_session || state() != QMediaRecorder::PausedState)
         return;
     heartbeat.start();
-    gstEncoder.setState(GST_STATE_PLAYING);
     stateChanged(QMediaRecorder::RecordingState);
 }
 
@@ -365,46 +371,29 @@ void QGstreamerMediaEncoder::stop()
         return;
     qCDebug(qLcMediaEncoder) << "stop";
 
-    gstPipeline.beginConfig();
-
-    if (!audioSrcPad.isNull()) {
-        audioSrcPad.unlinkPeer();
-        m_session->releaseAudioPad(audioSrcPad);
-        audioSrcPad = {};
-    }
-    if (!videoSrcPad.isNull()) {
-        videoSrcPad.unlinkPeer();
-        m_session->releaseVideoPad(videoSrcPad);
-        videoSrcPad = {};
-    }
-
-    gstPipeline.endConfig();
+    m_session->unlinkEncoder();
 
     //with live sources it's necessary to send EOS even to pipeline
     //before going to STOPPED state
     qCDebug(qLcMediaEncoder) << ">>>>>>>>>>>>> sending EOS";
-
     gstEncoder.sendEos();
-    stateChanged(QMediaRecorder::StoppedState);
 }
 
 void QGstreamerMediaEncoder::finalize()
 {
     if (!m_session || gstEncoder.isNull())
         return;
-    qCDebug(qLcMediaEncoder) << "finalize";
 
+    qCDebug(qLcMediaEncoder) << "finalize";
     heartbeat.stop();
 
-    // The filesink can only be used once, replace it with a new one
-    gstPipeline.beginConfig();
     gstEncoder.setState(GST_STATE_NULL);
     gstFileSink.setState(GST_STATE_NULL);
     gstPipeline.remove(gstEncoder);
     gstPipeline.remove(gstFileSink);
     gstFileSink = {};
     gstEncoder = {};
-    gstPipeline.endConfig();
+    stateChanged(QMediaRecorder::StoppedState);
 }
 
 void QGstreamerMediaEncoder::setMetaData(const QMediaMetaData &metaData)
diff --git a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder_p.h b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder_p.h
index 7570a939b..2c9b480ce 100644
--- a/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder_p.h
+++ b/src/multimedia/platform/gstreamer/mediacapture/qgstreamermediaencoder_p.h
@@ -86,6 +86,7 @@ public:
 
     void setCaptureSession(QPlatformMediaCaptureSession *session);
 
+    QGstElement getEncoder() { return gstEncoder; }
 private:
     bool processBusMessage(const QGstreamerMessage& message) override;
 public:
@@ -117,9 +118,6 @@ private:
     QGstPipeline gstPipeline;
     QGstBin gstEncoder;
     QGstElement gstFileSink;
-
-    QGstPad audioSrcPad;
-    QGstPad videoSrcPad;
 };
 
 QT_END_NAMESPACE