башизмы

for 1 to 28
for i in $(seq 1 28) ; do echo $i ; done 

cut video fragment
ffmpeg -i input.mp4 -acodec copy -vcodec copy -ss 00:17:00 -t 00:02:00 output.mp4

double video speed

mencoder -speed 2 -o output.avi -ovc lavc -nosound input.mp4