[FFmpeg-user] join two video files portions

[Liam Condron-Farnos]

>and I got a Duration = N/A .  The problem is the file is opened and
recording from >webcam...
>In fact, when recording is stopped, I get correct duration.

Of course, ffprobe won't be able to get the duration of a file that is in
the process of being created. That information can't be known, because it
will be constantly changing. Or am I misunderstanding what you are asking
for?