Cropping a section of a video and saving it without reencoding is very simple, the example below shows how to use ffmpeg to cut out a section of video and then save it to a separate file.
This example will cut out a clip starting 12 minutes into the video and 13 minutes long.
4.4 Wed Mar 27 jason@Yog-Sothoth 0: $ ffmpeg -i 'Game.of.Thrones.S06E07.720p.HDTV.x264-AVS.mkv' -ss 00:12:00 -t 00:13:00 -c:v copy -c:a copy output.mkv |
This example cuts A clip 14 minutes into the video, 20 seconds long and saves it to a separate file.
4.4 Wed Mar 27 jason@Yog-Sothoth 0: $ ffmpeg -i 'Game.of.Thrones.S06E07.720p.HDTV.x264-AVS.mkv' -ss 00:14:00 -t 00:00:20 -c:v copy -c:a copy output.mkv |
The -ss 00:14:00 parameter tells ffmpeg when to start cutting the clip.
The -t 00:00:20 parameter tells ffmpeg how long the clip will be. In this case, it is 20 seconds.
This parameter: -c:v copy -c:a copy, tells fffmpeg to just copy the video format to the new clip and not to reencode it at all.
This is how easy it is to cut clips out of a video using the command line, this is pretty accurate and works very well for clipping out a vid for Youtube or video editing.