ffmpeg input from images stream out video
Couldn't wait! Figured it out:

I saved an image to the file out.png at a fixed frame rate from processing.

Created a fifo:

mkfifo fifo


Then in one terminal:

tail -f out.png  &gt; fifo


Then in another terminal:

cat fifo | ffmpeg  -f image2pipe -r 1 -i pipe:0 spo.mp4


Making sure to close tail first allowing ffmpeg to write the last bit of the file.