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

FFmpeg trac at avcodec.org
Sat Oct 16 22:41:18 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:18 Elon Musk]:
 > That lerp with absolute rotation have nothing to do with this filter,
 iirc its happening in every app that use absolute rotations with lerp.
 >
 > Read for example https://answers.unity.com/questions/717637/how-do-you-
 smoothly-transitionlerp-into-a-new-rota.html

 I'm more than happy to accept the slight weirdness implied by
 interpolating and forcing in the absolute Euler angles as long as it's
 possible and there's a good match between the interactive and sendcmd
 versions, which this gets to without a doubt.

 I suppose an alternative to drop the absolute behaviour and have correct
 Quaternion controlled rotation and make this use pure relative would be to
 expose an additional property (alongside T,IT,N and the others) to the
 sendcmd expressions that allows it to work out how many frames are going
 to be emitted during the command interval so sendcmd scripts can use that
 as a divisor and emit the correct small slice of rotation each eval.

 I suppose that'd be more pleasing for allowing the internals to be a more
 pure Qauternion based rotation, but as I say I'm more than delighted with
 this being functional with this flag in place!
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Ticket URL: <https://trac.ffmpeg.org/ticket/9447#comment:19>
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