Title: How to remove a part of a video using ffmpeg
       Author: Solène
       Date: 02 October 2019
       Tags: ffmpeg
       Description: 
       
       If you want to remove parts of a video, you have to cut it into pieces
       and then
       merge the pieces, so you can avoid parts you don't want.
       
       The command is not obvious at all (like in all ffmpeg uses), I found
       some parts
       on differents areas of the Internet.
       
       Split in parts, we want to keep from 00:00:00 to 00:30:00 and 00:35:00
       to 00:45:00
       
           ffmpeg -i source_file.mp4 -ss 00:00:00 -t 00:30:00 -acodec copy
       -vcodec copy part1.mp4
           ffmpeg -i source_file.mp4 -ss 00:35:00 -t 00:10:00 -acodec copy
       -vcodec copy part2.mp4
       
       The -ss parameter tells ffmpeg where to start the video and -t
       parameter tells
       it about the duration.
       
       Then, merge the files into one file:
       
           printf "file %s\n" part1.mp4 part2.mp4 > file_list.txt
           ffmpeg -f concat -i file_list.txt -c copy result.mp4
       
       instead of printf you can write into file_list.txt the list of files
       like this:
       
           file /path/to/test1.mp4
           file /path/to/test2.mp4