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v360 ball 1 - animate yaw

The v360 filter has many projection formats, here the "ball" format. No practical use for a panoramic photographer, but visually interesting. To make a flat video in ball format from an equirectangular file, I decided to make 360 equirectangular images with 1° horizontal increase*. Starting from the left, position -180 to 180 (the yaw range in v360).

ffmpeg v360 filter

* to vary the number of frames, I have to leave bash as it only accepts integers. I would use Black Magic Design's Fusion Studio with Reactor to directly make an intermediate movie in any length.



180e.jpg
Equirectangular input (as .tif), the Buddha hall, National Museum, Phnom Penh, 2007.

Introduction to Bash Shell Scripting, Flavio Copes
Bash - Getting started with Bash
shellcheck is your friend when the shell is stubborn

To make a batch, use bash or zsh as follows:

#!/bin/bash
yaw=-180# degrees, range -180 to 180. If you want to loop it, stop at 179.
frame=0# start from 0.
while [ $frame -lt 360 ]# (-lt = less than) loop from 0 to 359 frames, then stop.
do
ffmpeg -i a/input.tif -hide_banner -vf v360=input=e:output=e:yaw="$yaw" b/"$frame".jpg
yaw=$((yaw + 1))# increase yaw by one (integer).
frame=$((frame + 1))# increase image number.
done

Then, add 00 to image 1-9, add 0 to 10-99 for the next step (or use a file renamer):

a=1
for i in *.jpg; do
new=$(printf "%03d.jpg" ${a})
echo renaming ${i} ${new}
mv ${i} ${new}
let a=a+1
done

Make a high quality intermediate movie from the jpeg files in .mov or .mkv format:
(and with that movie you can make more experiments. Perhaps a version of "Little Planet",
ffmpeg -i proRes422.mov -vf v360=input=equirect:output=fisheye:h_fov=360:v_fov=360:pitch=-90 -y lplanet01.mov
It just rotates, it gets more interesting if you also animate pitch in the source movie.
Thanks Michael Koch, "2.120 Remap an equirectangular video to a "Little planet" video" see info

	pitch=
	 90  68  45
	 22   0 -22
	-45 -68 -90 

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