[FFmpeg-user] Cutting out part of a video does not work

[Michael Koch]

Am 26.03.2021 um 09:55 schrieb Cecil Westerhof via ffmpeg-user:
> I want to publish a speech I gave during a Zoom meeting. But cutting
> it out does not work.
>
> When I use:
>      ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1190 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4
>
> The video starts just a bit to late. But when I use:
>      ffmpeg -y -i 2021-03-25ToastmastersClubAvond.mp4 -ss 1185 -to 1631 -acodec copy -vcodec copy -async 1 speech.mp4
>
> which is five seconds earlier. I get the same output.
>
> Am I doing something wrong?

Without re-encoding you can only cut at keyframes.
If you want to cut at exact times, you must remove -acodec copy and 
-vcodec copy

Michael