Public service announcement: To decode QR codes on your computer with your webcam, one option is to use the zxing gstreamer plugin (gst-plugins-bad on Arch) and then run this: gst-launch-1.0 --gst-debug=zxing:9 v4l2src ! videoconvert ! zxing ! videoconvert ! autovideosink You get a live preview and it prints to stdout once something has been decoded successfully.