While investigating the circumstances of http://avidemux.org/smif/index.php/topic,17008.0.html (http://avidemux.org/smif/index.php/topic,17008.0.html), I played with a Qt4 build of Avidemux and saw that German umlauts like in "Videodatei wählen..." for avidemux/common/gui_main.cpp:340 in the title bar of the filepicker are displayed as garbage. This problem doesn't exist on Qt5.
Does Qt4 need some special utf-8 treatment?
Qt4 is being obsoleted (in general, not by me)
Not sure it's worth the time