FFmpeg cheat sheet
Recent -to. -c copy copies the first video, audio, and subtitle bitstream from the input to the output file without re-encoding them. This wont harm the quality and make the command run within seconds. With re-encoding: -c copy option, ffmpeg will automatically re-encode the output video and audio according to the format you chose. For high quality video and audio, read the x264 Encoding Guide and the AAC Encoding Guide, respectively. For example: ffmpeg -ss [start] -i in.mp4 -t [duration] -c...
Source: github.com