How to extract one frame of a video every N seconds to an image?

It's very simple with ffmpeg, and it can output one frame every N seconds without extra scripting. To export as an image sequence just use or similar as the output. The bit is converted to a zero-padded integer digits long - the example I gave gets output as , , etc.. You can use lots of still image formats, png, jpeg, tga, whatever (see for a full list). Ok so now we know how to export the movie as a sequence of images, but say we don't want to export every single frame? The trick is to simply…