[FFmpeg-trac] #9447(avfilter:closed): avfilter/vf_v360 interprets commands as relative rotation offsets

FFmpeg trac at avcodec.org
Wed Oct 20 23:19:59 EEST 2021


#9447: avfilter/vf_v360 interprets commands as relative rotation offsets
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             Reporter:  Saul Baker  |                    Owner:  (none)
                 Type:  defect      |                   Status:  closed
             Priority:  normal      |                Component:  avfilter
              Version:  git-master  |               Resolution:  invalid
             Keywords:  v360        |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by Saul Baker):

 Replying to [comment:33 Elon Musk]:
 > quaternion matrix is changed only when yaw/pitch/roll are not 0

 Perfectly correct that's '''precisely''' the issue, it's being reset to
 origin when reset_rot is set, and then the yaw,pitch,roll are being set to
 zero, and then it's applying the commands to update the yaw,pitch,roll
 with new values, if none of the commands in that command interval are
 changing the yaw/pitch/roll they stay at zero and as you rightly say: no
 update to the quaternion and it stays in it's reset state pointing at
 origin for that axis.

 For example with the command sequence:

 {{{
 0.0000-1.2622 [expr] v360 at 1 reset_rot '1', v360 at 1 pitch
 'lerp(-15.0000,-15.0000,TI)';
 1.2622-2.8044 [expr] v360 at 1 reset_rot '1', v360 at 1 pitch
 'lerp(-15.0000,15.0000,TI)';
 0.0000-3.6991 [expr] v360 at 1 reset_rot '1', v360 at 1 yaw
 'lerp(-20.0000,-20.0000,TI)';
 3.6991-4.9172 [expr] v360 at 1 reset_rot '1', v360 at 1 yaw
 'lerp(-20.0000,20.0000,TI)';
 }}}

 Produces the attached 'Pitch reset on subsequent yaw command' example
 where on execute of the yaw commands that don't mention the pitch the
 pitch is reset to origin  - however if the yaw/pitch/roll were not zeroed
 when {{{reset_rot!=0}}} the pitch would have retained its prior value
 correctly rotating to the previously specified command's angle of
 15degrees upwards even as it was lerping through the yaw sweep.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9447#comment:34>
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