QmlGlSink BlackScreen on Rtsp Display

FLavenN

When i try to build & run the example down below i see the videotestsrc in my qml. But i can not do the same for a rtsp stream. Only thing that i get is a black screen ? Any help would be appreciated.

Here is the example : https://github.com/GStreamer/gst-plugins-good/tree/1.18/tests/examples/qt/qmlsink

And here is a part of my code :

    GstElement *pipeline = gst_pipeline_new(NULL);
    GstElement *src = gst_element_factory_make("rtspsrc",NULL);
    GstElement *rtph264depay = gst_element_factory_make("rtph264depay",NULL);
    GstElement *h264parse = gst_element_factory_make("h264parse",NULL);
    //GstElement *encoder = gst_element_factory_make("x264enc",NULL);
    GstElement *decoder = gst_element_factory_make("avdec_h264",NULL);
    GstElement *glupload = gst_element_factory_make("glupload",NULL);
    GstElement *glcolorconvert = gst_element_factory_make("glcolorconvert",NULL);
    GstElement *qmlglsink = gst_element_factory_make("qmlglsink",NULL);

    g_assert(src  && rtph264depay && h264parse && decoder && glupload &&  glcolorconvert && qmlglsink);

    g_object_set(G_OBJECT(src), "location", "rtsp://localhost:9300/" , NULL);
    gst_bin_add_many(GST_BIN(pipeline), src, rtph264depay,h264parse,decoder,glupload,  glcolorconvert , qmlglsink , NULL );
    gst_element_link_many(src,  rtph264depay,h264parse,decoder,glupload,  glcolorconvert , qmlglsink , NULL);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    QQuickItem *videoItem;
    QQuickWindow *rootObject;

    /* find and set the videoItem on the sink */
    rootObject = static_cast<QQuickWindow *> (engine.rootObjects().first());
    videoItem = rootObject->findChild<QQuickItem *> ("videoItem");
    g_assert (videoItem);
    g_object_set(qmlglsink , "widget", videoItem, NULL);

    rootObject->scheduleRenderJob (new SetPlaying (pipeline),
                                   QQuickWindow::BeforeSynchronizingStage);

    ret = app.exec();

SGaist

Hi and welcome to devnet,

Beside the QML sink, are you sure the rest of the pipeline is correct ?

FLavenN

Yes i guess so i've tried other pipelines that works correctly. But what i've noticed when i use decodebin i get black screen.

FLavenN

@SGaist When i use some pipeline like this :

gst-launch-1.0 filesrc location=C:/Users/X/Desktop/Stabil.mp4 ! decodebin ! glupload ! glcolorconvert ! glimagesink

It works but when i convert this to my code i guess the decodebin what makes it looks like a black screen.

And here is my code for a pipeline like this :

    GstElement *pipeline = gst_pipeline_new (NULL);
    GstElement *src = gst_element_factory_make ("filesrc", NULL);
    GstElement *decoder = gst_element_factory_make("decodebin",NULL);
    GstElement *glupload = gst_element_factory_make ("glupload", NULL);
    GstElement *glcolorconvert = gst_element_factory_make("glcolorconvert",NULL);
    /* the plugin must be loaded before loading the qml file to register the
         * GstGLVideoItem qml item */
    GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);
    g_object_set(G_OBJECT(src), "location", "C:/Users/X/Desktop/Stabil.mp4" , NULL);
    g_assert (src &&  decoder &&  glupload && glcolorconvert &&  sink);

    gst_bin_add_many (GST_BIN (pipeline), src, decoder , glupload,  glcolorconvert , sink, NULL);
    gst_element_link_pads(src, "src", decoder, "sink");
    gst_element_link_many (src,  decoder , glupload, glcolorconvert , sink, NULL);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    QQuickItem *videoItem;
    QQuickWindow *rootObject;

    /* find and set the videoItem on the sink */
    rootObject = static_cast<QQuickWindow *> (engine.rootObjects().first());
    videoItem = rootObject->findChild<QQuickItem *> ("videoItem");
    g_assert (videoItem);
    g_object_set(sink , "widget", videoItem, NULL);

    rootObject->scheduleRenderJob (new SetPlaying (pipeline),
                                   QQuickWindow::BeforeSynchronizingStage);

    ret = app.exec();

nishithaa

Please verify which is the decoder element used by decodebin. If you had installed vaapi plugins, then decodebin takes that element by default , and not avdec_h264. vaapi decoder output cannot be directly linked to qmlsink