I have an MKV video, and want to cut the first 3 seconds. I tried with FFmpeg:
ffmpeg -i /input.mkv -ss 00:00:3.0 -c copy -t 00:09:58.0 output.mkv
But the result (when played in VLC) is that there are 5 seconds blank video with the original sound, and after that, the video shows.
I think it has something to do with a missing keyframe at the beginning. So I tried:
ffmpeg -i /input.mkv -ss 00:00:3.0 -c copy -t 00:09:58.0 -force_key_frames 00:00:00.000 output.mkv
But this has no effect - same result.
How can I cut a video properly so that it begins exactly where cut?