Optimize thumbnail extraction

[Petr Nejedly]

It seems that placing -ss in front of the input file makes it faster

http://www.php-code.net/2010/07/capturing-multiple-thumbnails-from-a-movie-using-ffmpeg/

[Illico]

Don't know if libavfilter option is better http://www.ffmpeg.org/libavfilter.html#thumbnail

ffmpeg -i in.avi -vf thumbnail,scale=120:120 -frames:v 1 out.png

[Petr Nejedly]

I looked at this, but think it's related to finding the best thumbnail, ie not just black frame for example. It might be even slower actually.