Run this script in the folder where the .png images are stored. mencoder will create a avi video with the given framerate (fps).
mencoder mf://*.png -mf w=800:h=600:fps=25:type=png -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:trell -oac copy -o output.avi
This snippet has been viewed 26300 times.