Hi Hans, I just rebuilt latest v4l-utils master and unfortunately found a problem with qv4l2. I run it on my target devices with X forwarding and after commit 56175f62bef28490 ("qv4l2: fix CaptureWin::setWindowSize() if there are multiple screens") I get a segmentation fault when I try to start a capture. When the windows that displays the capture is suppose to pop-up it crashes as it tries to dereference a nullptr. I bisected the problem to the mentioned commit and the change - QScreen *screen = QGuiApplication::screenAt(mapToGlobal({width() / 2, 0})); + QScreen *screen = window()->windowHandle()->screen(); After the change window()->windowHandle() returns a nullptr for me and then I die. -- Regards, Niklas Söderlund