GStreamer: link camera bin only when pipeline is paused

Task-id: QTBUG-122638
Pick-to: 6.5
Change-Id: I057a915394aba710d8eac94f98fed28c67822004
Reviewed-by: Mikko Hallamaa <mikko.hallamaa@qt.io>
Reviewed-by: Lars Sutterud <lars.sutterud@qt.io>
Reviewed-by: Jøger Hansegård <joger.hansegard@qt.io>
Reviewed-by: Artem Dyomin <artem.dyomin@qt.io>
(cherry picked from commit a4fab41303f67ccfae3716ad64ea354c8669998d)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
(cherry picked from commit c7b54e31c7da3c1e1b55d66efc9ee8ecaba27963)

1 files changed, 24 insertions, 22 deletions

diff --git a/src/plugins/multimedia/gstreamer/mediacapture/qgstreamermediacapture.cpp b/src/plugins/multimedia/gstreamer/mediacapture/qgstreamermediacapture.cpp
index 28b985fa2..6520272a6 100644
--- a/src/plugins/multimedia/gstreamer/mediacapture/qgstreamermediacapture.cpp
+++ b/src/plugins/multimedia/gstreamer/mediacapture/qgstreamermediacapture.cpp
@@ -89,36 +89,38 @@ void QGstreamerMediaCapture::setCamera(QPlatformCamera *camera)
     if (gstCamera == control)
         return;
 
-    if (gstCamera) {
-        unlinkTeeFromPad(gstVideoTee, encoderVideoSink);
-        unlinkTeeFromPad(gstVideoTee, imageCaptureSink);
+    gstPipeline.modifyPipelineWhileNotRunning([&] {
+        if (gstCamera) {
+            unlinkTeeFromPad(gstVideoTee, encoderVideoSink);
+            unlinkTeeFromPad(gstVideoTee, imageCaptureSink);
 
-        auto camera = gstCamera->gstElement();
+            auto camera = gstCamera->gstElement();
 
-        gstPipeline.stopAndRemoveElements(camera, gstVideoTee, gstVideoOutput->gstElement());
+            gstPipeline.stopAndRemoveElements(camera, gstVideoTee, gstVideoOutput->gstElement());
 
-        gstVideoTee = {};
-        gstCamera->setCaptureSession(nullptr);
-    }
+            gstVideoTee = {};
+            gstCamera->setCaptureSession(nullptr);
+        }
 
-    gstCamera = control;
-    if (gstCamera) {
-        QGstElement camera = gstCamera->gstElement();
-        gstVideoTee = QGstElement::createFromFactory("tee", "videotee");
-        gstVideoTee.set("allow-not-linked", true);
+        gstCamera = control;
+        if (gstCamera) {
+            QGstElement camera = gstCamera->gstElement();
+            gstVideoTee = QGstElement::createFromFactory("tee", "videotee");
+            gstVideoTee.set("allow-not-linked", true);
 
-        gstPipeline.add(gstVideoOutput->gstElement(), camera, gstVideoTee);
+            gstPipeline.add(gstVideoOutput->gstElement(), camera, gstVideoTee);
 
-        linkTeeToPad(gstVideoTee, encoderVideoSink);
-        linkTeeToPad(gstVideoTee, gstVideoOutput->gstElement().staticPad("sink"));
-        linkTeeToPad(gstVideoTee, imageCaptureSink);
+            linkTeeToPad(gstVideoTee, encoderVideoSink);
+            linkTeeToPad(gstVideoTee, gstVideoOutput->gstElement().staticPad("sink"));
+            linkTeeToPad(gstVideoTee, imageCaptureSink);
 
-        qLinkGstElements(camera, gstVideoTee);
+            qLinkGstElements(camera, gstVideoTee);
 
-        gstVideoOutput->gstElement().setState(GST_STATE_PLAYING);
-        gstVideoTee.setState(GST_STATE_PLAYING);
-        camera.setState(GST_STATE_PLAYING);
-    }
+            gstVideoOutput->gstElement().setState(GST_STATE_PLAYING);
+            gstVideoTee.setState(GST_STATE_PLAYING);
+            camera.setState(GST_STATE_PLAYING);
+        }
+    });
 
     gstPipeline.dumpGraph("camera");