Windows are displayed separately when embedding video stream into gtk4

[mytruong12]

I tried to integrate a video stream from a webcam and display it on the GTK4 application window. But the video window is displayed separately. How can I fix this error?

static void setup_video_pipeline(GtkWidget *video_area) {
    GstElement *video_source, *video_convert, *video_sink;

    video_source = gst_element_factory_make("v4l2src", "video_source");
    video_convert = gst_element_factory_make("videoconvert", "video_convert");

    #ifdef GDK_WINDOWING_X11
    video_sink = gst_element_factory_make("xvimagesink", "video_sink");
    #endif
    #ifdef GDK_WINDOWING_WAYLAND
    video_sink = gst_element_factory_make("waylandsink", "video_sink");
    #endif

    if (!video_source || !video_convert || !video_sink) {
        g_printerr("Failed to create one or more GStreamer elements:\n");
        if (video_source) gst_object_unref(video_source);
        if (video_convert) gst_object_unref(video_convert);
        if (video_sink) gst_object_unref(video_sink);
        return;
    }

    pipeline = gst_pipeline_new("video_pipeline");
    gst_bin_add_many(GST_BIN(pipeline), video_source, video_convert, video_sink, NULL);

    if (!gst_element_link_many(video_source, video_convert, video_sink, NULL)) {
        g_printerr("Elements could not be linked.\n");
        gst_object_unref(pipeline);
        pipeline = NULL;
        return;
    }

    #ifdef GDK_WINDOWING_X11
    if (GDK_IS_X11_DISPLAY(gdk_display_get_default())) {
        video_window_handle = GDK_SURFACE_XID(gtk_native_get_surface(gtk_widget_get_native(video_area)));
    }
    #endif

    #ifdef GDK_WINDOWING_WAYLAND
    if (GDK_IS_WAYLAND_DISPLAY(gdk_display_get_default())) {
        video_window_handle = (guintptr) gdk_wayland_surface_get_wl_surface(gtk_native_get_surface(gtk_widget_get_native(video_area)));
    }
    #endif

    if (video_window_handle) {
        gst_video_overlay_set_window_handle(GST_VIDEO_OVERLAY(video_sink), video_window_handle);
        gst_element_set_state(pipeline, GST_STATE_PLAYING);
    } else {
        g_printerr("Failed to set video window handle.\n");
    }

    gst_element_set_state(pipeline, GST_STATE_PLAYING);
}

static void realize_cb(GtkWidget *widget, gpointer data) {
    setup_video_pipeline(widget);  
}