Video playback distorted

Hi, I’m running the latest (!7.1) version of Kodi on a Intel NUC. When I play back some videos via Kodi, the image is distorted – the left and right edges are stretched and the centre is squashed. I’ve tried various settings – I’ve turned HW decoding on and off and deinterlacing on & off. The videos are correct if I use the Windows video player. It doesn’t affect all videos – I’ve noticed it on M4V suffixed videos.

-Andrew