Splitting video in multiple episodes with ffmpeg

Question

I need to cut one video into multiple pieces with ffmpeg.

When I cut just one episode

ffmpeg -i 001.mp4 -vcodec copy -acodec copy -ss 00:00:00.000 -t 00:00:25.500 -strict -2 out1.mp4

or

ffmpeg -i 001.mp4 -vcodec copy -acodec copy -ss 00:00:25.500 -t 00:00:33.750 -strict -2 out2.mp4

my video is cut instantaneously.

But when I chain markers where I'd like to cut

ffmpeg -i 001.mp4 -vcodec copy -acodec copy -ss 00:00:00.000 -t 00:00:25.500 -strict -2 out1.mp4 -ss 00:00:25.500 -t 00:00:33.750 -strict -2 out2.mp4

it still works, but it takes considerably more time (about 10 sec), and I see the same output as when I convert something.

Is something wrong with my ffmpeg-command, or it is better to execute ffmpeg-commands one by one?

Answer 1

ffmpeg is probably re-encoding out2.mp4 because you did not include your copy options for your second output:

ffmpeg -i 001.mp4 -codec copy -t 00:00:25.5 out1.mp4 -codec copy -ss 00:00:25.5 -t 00:00:33.75 out2.mp4

• -strict -2 is not required in this case. If you are re-encoding, and no other AAC encoders are available, then ffmpeg will use -codec:a aac which requires -strict -2 (or the alias -strict experimental which I prefer).

• -codec copy will copy all streams of each type if present. For MP4 that usually just means audio and video, but other containers can have subtitles or even a data stream.

• You do not need to use -ss if the value is 0.