Rotate webcam video in empathy

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http://askubuntu.com – I have a Lenovo x220 Tablet laptop with a built-in webcam, which is shown by lsusb as a Chicony Electronics Co., Ltd device (device id 04f2:b217). The uvcvideo kernel module is used as a driver for it. The webcam is working out-of-the-box under Ubuntu 12.04 (very nice!), but the video is upside-down (for example in Empathy and when I open /dev/video0 with vlc). So how can I rotate the webcam video by 180° degrees? I would prefer an application-independent solution, because for example Empathy seems to have no settings for this. (HowTos)