ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" -an output.mp4
http://superuser.com/questions/777938/ffmpeg-convert-a-video-to-a-timelapse?answertab=votes#tab-top
ffmpeg -i input.mp4 -filter:v "setpts=0.5*PTS" -an output.mp4
http://superuser.com/questions/777938/ffmpeg-convert-a-video-to-a-timelapse?answertab=votes#tab-top