Dump keyframes of a livestream I'm trying to create a "highlights" gallery for an event that's been livestreamed (say an Apple product launch keynote or similar H264 stream) - is there a way using FFMPEG to dump all the keyframes / a frame every 5 seconds into a folder as images? I can then curate the most interesting ones. 

I'd think that keyframes are a better bet because they'd represent a scene or camera angle change, which would correspond to "interestingness", but are there any other better ways to do this?
Basic form is

ffmpeg -i livestream -vf select=key -vsync 0 -q:v 1 snaps%d.jpg