[FFmpeg-trac] #10912(undetermined:new): d_fov and h_fov not working well when converting equirectangular to rectilinear (v360)

[FFmpeg]

#10912: d_fov and h_fov not working well when converting equirectangular to
rectilinear (v360)
-------------------------------------+-------------------------------------
             Reporter:  0kajuna0     |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  git-master   |               Resolution:
             Keywords:  v360,        |               Blocked By:
  equirect, rectilinear              |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Comment (by claude):

 I ran into this problem too, when using ffmpeg to turn an equirectangular
 panorama into a set of rectilinear snapshots, which I then reconstructed
 into an equirectangular panoram with Hugin.

 {{{
 ffmpeg -i in.tif \
 -vf
 "v360=input=equirect:output=rectilinear:d_fov=68.84:w=640:h=360:yaw=$Y:pitch=$P:roll=$R"
 \
 out.png
 }}}

 (with `$Y $P $R` set to many pseudorandom choices) can be reconstructed to
 a panorama using Hugin (setting HFOV 60 for its input), where `68.84 =
 sqrt(60^2 + (60/640*360)^2)` without any glitches, but recombining the
 outputs from

 {{{
 ffmpeg -i in.tif \
 -vf
 "v360=input=equirect:output=rectilinear:h_fov=60:w=640:h=360:yaw=$Y:pitch=$P:roll=$R"
 \
 out.png
 }}}

 results in weird errors / mismatched overlap / seams.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10912#comment:2>
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