As a last desperate attempt, I tried installing the player software from Astrometa (TVRplayer) and... it works. The picture is fine in TVRplayer, no more video glitches.
I don't know why, maybe this software includes some driver level hacks that make it work with this device.

In ProgDVB and VLC it ...

I know they need more signal, I've used several USB DVB-T devices on my PC in the past, usually very cheap ones too. But I've never seen anything like this. The way this one behaves is not normal.

Do you have good signal on same device in other software?
I tried in VLC now and it's even worse than in ProgDVB. The picture freezes all the time.


You can check signal quality in ProgDVB -> File->Input traffic->packet lost

It shows a constant loss ("Minimal lost"). After a few minutes it ...

I bought this Chinese USB DVB-T tuner: https://linuxtv.org/wiki/index.php/Astrometa_DVB-T2

The problem is that when I watch DVB-T channels in ProgDVB I get glitches, as if the signal/reception was bad (smeared, blocky picture). But the signal is fine. Even if the signal is 100% it still glitches ...