A convenience when doing these tests is to apply the "Downsample" filter to the timeline track and set it, in H and W, to at least the value 40. This will immediately show whether the pixel shape is square or rectangular, and, in the latter case, whether it is stretched vertically or horizontally. There is also to mention the "Auto aspect ratio" option in Set Format. It always returns the pixel (PAR) to the square shape by changing the DAR. If you leave the Auto checked box, every time we make a change it is reset to the square pixel. Auto, however, turns off if you set one of the presets and you have to re-enable it manually. Crop or sometimes pad (letterbox) is unavoidable when we impose a different aspect ratio from the starting one. I'm running tests with Terje's sample (thanks!) and getting the same results as him. I honestly don't understand the difference in rendering between CinGG and ffmpeg. In Cingg the initial SAR (actually the PAR) goes from 4:3 (=1.333) to 64:45 (=1.422). However, 1,422 is the correct value (for CinGG), to see Raffaella Traniello's guide: http://www.g-raffa.eu/Cinelerra/HOWTO/anamorphic.html I still have to make a new build with Andrew's last 2 patches (for DV 16:9) to see if anything changes.