gst-launch -- take a bunch of png files, flip them vertically, and stuff them into a theora file.

encode-pngs-theora.sh

#!/bin/bash
rm -r /tmp/frames
mkdir /tmp/frames
ln /home/zach/projects/Desulfurize/screenshots/*png /tmp/frames/

COUNTER=0
for FILE in `ls /tmp/frames`; do
   mv /tmp/frames/$FILE    /tmp/frames/`printf "%04d" $COUNTER`.png
   COUNTER=$(($COUNTER+1))
done

gst-launch multifilesrc location="/tmp/frames/%04d.png" index=0  \
   ! image/png,framerate=\(fraction\)5/1 !  \
   pngdec ! videorate ! videoflip method=5 ! ffmpegcolorspace ! \
   theoraenc quality=63 ! oggmux !  \
   filesink location="images.ogg"

# videorate after pngdec, or else only one frame makes it to filesink for some reason.
# theoraenc quality=63: maximum quality, hopefully lossless,
# videoflip method=5: vertical flip. PDL::IO::Pic saves images flipped vertically for some reason.
# ffmpegcolorspace: I don't actually know what this does. converts from YUV to RGB perhaps?