Is there a fisheye or dual fisheye to equirectangular filter for ffmpeg?

Question

Or a way to do it with an existing filter? So that you could take in video from a fisheye or dual fisheye camera (such as the Ricoh Theta) and directly output equirectangular,

Answer 1

In the latest ffmpeg, you can do this to convert fisheye video to equirectangular now

ffmpeg -y -i in.mp4 -vf v360=dfisheye:e:yaw=-90 -c:v libx265 -b:v 40000k -bufsize 5000k -preset ultrafast -c:a copy out.mp4

Docs: https://ffmpeg.org/ffmpeg-filters.html#v360

Answer 2

The Remap filter does just this:

This filter copies pixel by pixel a source frame to a target frame. It remaps the pixels to a new x,y destination based on two files ymap/xmap.

Basic command syntax is

ffmpeg -i fisheye_grid_input.jpg -i fisheye_grid_xmap.pgm -i fisheye_grid_ymap.pgm -filter_complex remap out.png 

Also included at that link are the mapping files for

Ricoh Theta S camera: input files for resolution 1920x960(1080)