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v360 ball 1 - animate yaw (with bash / zsh)

The v360 filter has many projection formats, here the "ball" format. Seems to be a fisheye format close to 300° FOV with an alpha mask option. No practical use for a panoramic photographer, but visually interesting.

Here I animate the equirectangular file by making 360 equirectangular images with 1° horizontal increase*. Starting from the left, position -180 to 180 (the yaw range in v360).

ffmpeg v360 filter

* to increase 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. Something like this: fusion_reactor



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

software carpentry Bash Shell course
Bash Shell Scripting exercises learn programming the hard way
Bash - Getting started with Bash
Introduction to Bash Shell Scripting, Flavio Copes
shellcheck is your friend when the shell is stubborn.

To make a batch script, use bash or zsh as follows (delete the comments if in zsh):

#!/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 (proRes422 or better) or .mxf (DNxHD/DNxHR) format:

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

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