[FFmpeg-user] Problem in v360?

[Michael Koch]

Am 23.10.2020 um 18:46 schrieb Michael Koch:
> Am 23.10.2020 um 17:19 schrieb Michael Koch:
>> Hello,
>>
>> It seems there is a problem in the v360 filter. This command line 
>> doesn't rotate the correct point to the image center. The default 
>> rotation order should be yaw pitch roll, which means after the 
>> rotation the point with azimut 180° and height +45° should be in the 
>> center. It is nearby, but not in the center. Tested with latest 
>> Windows build, 2 days old.
>>
>> ffmpeg -i equirectangular_test.png -vf v360=e:e:yaw=-90:pitch=45 -y 
>> out.png
>
> If the rotation is only yaw or only pitch or only roll, then it's 
> working fine. But all rotations around two or more axes fail.

I'm not sure, but the problem might be in the function 
multiply_quaternion() in vf_v360.c
Please compare the signs with this Wikipedia article:
https://en.wikipedia.org/wiki/Quaternion#Hamilton_product

Michael