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