I understand the problem. >Also note this important point from that page: "If you use -ss with -c:v copy, the resulting bitstream might end up being choppy, no

I understand the problem. >Also note this important point from that page: "If you use -ss with -c:v copy, the resulting bitstream might end up being choppy, not playable, or out of sync with the audio stream, since ffmpeg is forced to only use/split on i-frames." > This means you need to re-encode the video, even if you want to just copy it, or risk it being choppy and out of sync. You could try just -c copy first, but if the video sucks you'll need to re-do it. From the link. ----- edit: if it aids understanding, I think i-frame means "interpolated frame" i.e. frame that depends on the previous and next frames. edit2: and "-c:v copy" means don't transcode (or "recode" as you say) the video, but simply copy it.