Notes

This is very basic script for generating a thumbnail from FFMPEG using a UNIX script.

#! /bin/bash
ffmpeg -i video.MTS -s sqcif -f image2 -vframes 1 thumb.jpg

Line 1 specifies the shell to be used to run the script.
Line 2 is the command to run FFMPEG.

-i videoFile.MTS denotes the input video

-s sqcif is the size which is actually 128×96. sqcif could be replaced by 128×96 if one desired.  It’s simply a preset in a collection of 29 or so preset video dimensions in FFMPEG.

-f image2 is the format and in this case it’s set to image2 which is a JPG.

-vframes 1 is the total number of frames

thumb.jpg is the filename for the output image.