Make sure you have mencoder package installed first.  Changing framerate or splitting the video needs more I/O speed than CPU, so instead of using multiple cores (trough mencoder options), make sure that you have fast disks for reading and writing.

Change video frame rate without re-encoding. This example changes frame rate to 18fps. If your video has sound, you should use -nosound option or specify audio encoder using -oac option.

mencoder -fps 18 -ovc copy inputvideofile.avi -o outputvideofile_18fps.avi

Splitting video without re-encoding. This example copies first 9 minutes of video to outputfile.

mencoder -oac copy -ovc copy -endpos 09:00 inputfile.avi -o outputfile.avi

Splitting video without re-encoding. This example skips first 9 minutes (seeks into position 09:01) and then copies minute and a half of video to outputfile.

mencoder -oac copy -ovc copy -ss 09:01 -endpos 01:30 inputfile.avi -o outputfile.avi

Splitting video without re-encoding. This example skips first 15 minutes and then copies rest of the video to outputfile.

mencoder -oac copy -ovc copy -ss 15:00 inputfile.avi -o outputfile.avi

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