Truncate a video using mencoder or ffmpeg - Truncar un vídeo usando mencoder o ffmpeg

Here are two methods of truncate a video, using mencoder and ffmpeg. Choose your preferred one:

$ mencoder -ss [start] -endpos [duration] -oac copy -ovc copy [inputfile] -o [outputfile]

$ ffmpeg -vcodec copy -acodec copy -i [inputfile] -ss [start] -t [duration] [outputfile]