GStreamer - Pipeline how to connect filesrc to qmlglsink - c++

Question

I'm new in the world of GStreamer, so I can't figure out how it works, and how to pair all GstElements.
I want to merge Video (mp4 for example, or any other video format) with qml (from Qt) as an overlay.
This example works perfectly fine.
GstElement *pipeline = gst_pipeline_new(NULL);
GstElement *src = gst_element_factory_make("videotestsrc",NULL);
GstElement *glupload = gst_element_factory_make("glupload",NULL);
GstElement *qmlglsink = gst_element_factory_make("qmlglsink",NULL);
g_assert(src && glupload && qmlglsink);
gst_bin_add_many(GST_BIN(pipeline), src, glupload, sink);
gst_element_link_many(src, glupload, sink, NULL);
But that example uses videotestsrc as Source, I would prefer to use something like filesrc.
I tried this code:
GstElement *pipeline = gst_pipeline_new (NULL);
GstElement *src = gst_element_factory_make ("filesrc", "file-source");
GstElement *parser = gst_element_factory_make("h264parse",NULL);
GstElement *decoder = gst_element_factory_make("avdec_h264",NULL);
GstElement *colors = gst_element_factory_make("glcolorconvert",NULL);
GstElement *glupload = gst_element_factory_make ("glupload", NULL);
GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);
g_assert (src && parser && decoder %% colors && glupload && sink);
g_object_set (G_OBJECT (src), "location", "file:///home/test.mp4", NULL);
gst_bin_add_many (GST_BIN (pipeline), src, parser, decoder, glupload, colors, sink, NULL);
gst_element_link_many (src, parser, decoder, glupload, colors, sink, NULL);
It compiles, but the output is just a black screen.
Since I'm not sure how the GStreamer pipeline works, I tried that.
First, get the file from memory with filesrc, then parse it with h265parse and decode it with avdec_h264. Then forward that (I guess raw uncompressed data) to glupload and make colors good with glcolorconvert, since qmlglsink uses RGBA, and avdec_h264 is I420. After colors, are adjusted forward it to qmlglsink to be displayed in qml.
I'm missing something, and I don't know how to pair GstElemnts, as I said I need to pair filesrc (any video format) and qmlglsink.

Answer 1

You can try like below
MediaPlayer{
id: playVideo
source: "gst-pipeline: filesrc location=/home/root/skim-debris.mp4 ! qtdemux ! avdec_h264 ! qtvideosink"
autoLoad: true
autoPlay: true
playbackRate: 1.0
loops: 10
}
VideoOutput {
anchors.fill: parent
source: playVideo
}

Answer 2

It is easier to use a bin or any of GStreamers auto-pluggers.
But the main issue here is that you try treating an MP4 file as H.264 stream. This cannot work this way. You need to demux media streams from your container.
E.g. the pipeline should be something like this:
gst-launch-1.0 filesrc location=/home/test.mp4 ! qtdemux ! \
h264parse ! avdec_h264 ! glupload ! glcolorconvert ! qmlglsink