https://www.youtube.com/playlist?list=PLhZFooxxjUJ8HMNnmO52vAUM5Pn0DB6ak
https://www.youtube.com/playlist?list=PLhZFooxxjUJ_bdNRSQgFQTxJiucl1yUdA

ffmpeg -ss 00:00:00 -t 00:49:12 -i 1.mp4 -sameq out1.mp4

ffmpeg -ss 00:00:00 -t 00:49:12 -i 1.mp4 -vcodec copy -acodec copy out1.mp4