ffmpeg -ss 00:10:00 -i input.mkv -t 60 -c:v libx264 -preset slow -crf 18 -c:a copy piece.mkv (adjust -ss start time, -t duration)
If you need help a piece yourself using h264 (e.g., with ffmpeg): outlander s03 h264
For Outlander S03 in , a correct example would be: ffmpeg -ss 00:10:00 -i input
If you mean (common in file sharing/torrents), a "proper" typically fixes a previous release's issue (sync, missing frames, bad audio). with ffmpeg): For Outlander S03 in