Watching GStreamer RTSP stream in QT6 Widget

MrHandSOme

I want to watch RTSP Stream in a widget in QT6, but although I specify it at the bottom of the code, it opens in a separate window called "Direct3D11 renderer", not on that qt app widget. If I delete all the elements in between, such as queue videoconvert, it works as I want, but this time there is a lot of delay.

    gst_init(nullptr, nullptr);
    
    GstElement *pipeline = gst_pipeline_new("video-pipeline");
    GstElement *rtspsrc = gst_element_factory_make("rtspsrc", "source");
    GstElement *queue = gst_element_factory_make("queue", "queue");
    GstElement *rtph264depay = gst_element_factory_make("rtph264depay", "depay");
    GstElement *h264parse = gst_element_factory_make("h264parse", "parse");
    GstElement *avdec_h264 = gst_element_factory_make("avdec_h264", "decoder");
    GstElement *videoconvert = gst_element_factory_make("videoconvert", "converter");
    GstElement *videoscale = gst_element_factory_make("videoscale", "scaler");
    GstElement *sink = gst_element_factory_make("autovideosink", "autovideosink");

    CHECK_ELEMENT(pipeline, "Pipeline");
    CHECK_ELEMENT(rtspsrc, "RTSP Source");
    CHECK_ELEMENT(queue, "Queue");
    CHECK_ELEMENT(rtph264depay, "RTP H264 Depayloader");
    CHECK_ELEMENT(h264parse, "H264 Parser");
    CHECK_ELEMENT(avdec_h264, "H264 Decoder");
    CHECK_ELEMENT(videoconvert, "Video Converter");
    CHECK_ELEMENT(videoscale, "Video Scaler");
    CHECK_ELEMENT(sink, "Video Sink");

    if (!pipeline || !rtspsrc || !queue || !rtph264depay || !h264parse || !avdec_h264 || !videoconvert || !videoscale || !sink) {
        return;
    }

    gst_bin_add_many(GST_BIN(pipeline), rtspsrc, queue, rtph264depay, h264parse, avdec_h264, videoconvert, videoscale, sink, nullptr);

    if (!gst_element_link_many(queue, rtph264depay, h264parse, avdec_h264, videoconvert, videoscale, sink, nullptr)) {
        gst_object_unref(pipeline);
        return;
    }

    g_object_set(G_OBJECT(rtspsrc), "location", "rtsp://127.0.0.1:8554/", nullptr);
    g_object_set(G_OBJECT(rtspsrc), "latency", 100, nullptr);

    g_signal_connect(rtspsrc, "pad-added", G_CALLBACK(+[](GstElement *src, GstPad *new_pad, gpointer data) {
                         GstElement *queue = GST_ELEMENT(data);
                         GstPad *sink_pad = gst_element_get_static_pad(queue, "sink");
                         if (gst_pad_is_linked(sink_pad)) {
                             g_object_unref(sink_pad);
                             return;
                         }
                         gst_pad_link(new_pad, sink_pad);
                         g_object_unref(sink_pad);
                     }), queue);

    WId windowId = ui->widgetCamera->winId();
    GstVideoOverlay *overlay = GST_VIDEO_OVERLAY(sink);
    gst_video_overlay_set_window_handle(overlay, static_cast<guintptr>(windowId));

    gst_element_set_state(pipeline, GST_STATE_PLAYING);

I want to see how to play RTSP Stream on qt widget.

JoeCFD

You are using autovideosink. In order to display RTSP streaming in Qt widget or qml layout, you need to replace autovideosink with qml or widget sink.
QML sink example is here.
https://github.com/GStreamer/gst-plugins-good/tree/master/tests/examples/qt

Note that Qt sinks are created and maintained by gstreamer developers, not by Qt company. If you have any issue with Qt sinks, ask gstreamer guys.