This
overview[
^] mentions the command
ffmpeg -f image2 -i image%d.jpg video.mpg
to convert images to video. It will be customizable to use arbitrary codecs, convert frame sizes, set frame rates and so on.
You will have to provide the images stored in a filesystem and adequatly named (with consequtive numbers in the filename).
Ignore this answer if your images are in memory instead of saved to a disk.