[FFmpeg-user] V360 filter

[Michael Koch]

Am 11.09.2019 um 13:13 schrieb Michael Koch:
> Paul,
>
>>> I think the field of view isn't correct in the stereographic output.
>>>
>>> Here is a script for making really nice test images, for measuring 
>>> field
>>> of view:
>> Well spotted, thanks, should be fixed.
>
> The field of view of the stereographic output isn't correct. Here are 
> a few examples:
> set in command line / measured in output image
> 60° / 74°
> 120° / 135°
> 180° / 180°
> 240° / 212°
> 300° / 236°
> 360° / 274°

Make this correction:

new_fov = 180 * tan(fov/4)

where fov the the field of view you get from the command line, and 
fov_new is the value that you use for the filter.
You must exclude values too close to 360°, because 360° stereographic 
projection is impossible.

Michael