Nasty artefacts on resolution changes in MediaPlayer with GStreamer pipeline

[SebastianM]

Hi,
in MediaPlayer I setup gst-pipeline and display it in VideoOutput item.
Depending on items size - 320x240 up to 1028x762 - IP Camera changes size of streamed content.
Still - before IP Camera change streamed resolution - for 1-2-3 sec VideoOutput display lower resolution on bigger item. Which looks bad.

mediaPlayer.source = "gst-pipeline: udpsrc port=123123 ! jpegparse ! jpegdec ! qtvideosink sync=false"

I would like to use some flag/property and cover VideoOutput with some image or animation till stream is stable.
I tried to use MediaPlayer.status or MediaPlayer.metaData to identify when higher resolution is present in stream. But no use. Status Buffered doesn't mean that video stream is high resolution.
MetaData are empty. I count the most on resolution field.

How else can I confirm that MediaPlayer plays high resolution video feed?