ffmpeg -f image2 -pattern_type glob -framerate 2 -i epoch*.png ../foo.avi
https://superuser.com/questions/249101/how-can-i-combine-30-000-images-into-a-timelapse-movie
ffmpeg -framerate 1/5 -i *%03d.png -c:v libx264 -r 30 -pix_fmt yuv420p out.mp4
https://askubuntu.com/questions/745732/converting-png-files-to-a-movie
Lossless:
ffmpeg -i %06d.png -c:v libx264 -r 30 -preset slower -qp 0 output.mkv