@Lahearle Hi!
I did manage to achieve this by using OpenCV, but since I have to do a conversion to embed in Qt, it does takes some CPU.
By the way, I used to stream webcams (connected to USB) in the past with Qt, by using Phonon in that era (with PyQt5). A webcam also have a indefinite amount of time.
But the problem here is not that. The problem is that I need to set TCP transport for RTSP (I already exposed that the same happens in FFmpeg if I do no set TCP as transport).
So, the behavior in Qt or FFmpeg is the same (which the difference that with FFmpeg I can set TCP transport).
So I think this has nothing to do with "indefinite stream time".
As a side note, when using FFmpeg command line directly (without setting TCP transport), I got the same output as with Qt... So.