user29391: I have several hours of CCTV footage that I'd like to reasonably quickly skim. If there was a way to take every say 60th frame from it and put together a video from those frames that would be perfect.
Is there a ffmpeg command that does that in one go? Or do I have to extract the frames first, and then encode a video from them?

user21133: See FFmpeg documentation regarding select filter https://ffmpeg.org/ffmpeg-filters.html#Examples-160, so to keep every 60th frame use -vf "select=not(mod(n\,60))"
And this has been already discussed with another example here Using select in ffmpeg to choose frames

29391: <p>I have several hours of CCTV footage that I'd like to reasonably quickly skim. If there was a way to take every say 60th frame from it and put together a video from those frames that would be perfect.</p>
<p>Is there a <code>ffmpeg</code> command that does that in one go? Or do I have to extract the frames first, and then encode a video from them?</p>
 21133: <p>See FFmpeg documentation regarding <code>select</code> filter <a href="https://ffmpeg.org/ffmpeg-filters.html#Examples-160" rel="nofollow noreferrer">https://ffmpeg.org/ffmpeg-filters.html#Examples-160</a>, so to keep every 60th frame use <code>-vf &quot;select=not(mod(n\,60))&quot;</code></p>
<p>And this has been already discussed with another example here <a href="https://video.stackexchange.com/questions/32756/using-select-in-ffmpeg-to-choose-frames">Using select in ffmpeg to choose frames</a></p>
