[FFmpeg-trac] #9617(avfilter:new): v360: rounding or +-1 errors

[FFmpeg]

#9617: v360: rounding or +-1 errors
-------------------------------------+-------------------------------------
             Reporter:  Michael      |                     Type:  defect
  Koch                               |
               Status:  new          |                 Priority:  normal
            Component:  avfilter     |                  Version:  git-
                                     |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I tested the v360 filter with all 36 combinations of these input/output
 formats: equirectangular, flat, fisheye, dfisheye, cylindrical and ball.
 The command lines are below.

 I found the following problems:

 eq2ball: in column y=0 there are 8 black pixels but 9 blue pixels, same
 problem in column y=179
 eq2fish: unsymmetric behaviour in x and y axes, pixel 0,37 is red but
 pixel 37,0 is black
 eq2dfish: the right circle has larger diameter than the left circle

 fish2eq: the vertical line in the center is between x=88 and x=89, it
 should be wetween x=89 and x=90
 fish2flat: that's clearly visible
 fish2ball: the vertical line in the center is between x=88 and x=89, it
 should be wetween x=89 and x=90, same problem also for the horizontal line
 fish2cyl: the vertical line in the center is between x=87 and x=88, it
 should be wetween x=89 and x=90

 dfish2eq: error at right edge
 dfish2dfish: unsymmetric behaviour in left circle
 dfish2cyl: error at 44,22 and right edege
 dfish2ball: that's clearly unsymmetric

 flat2eq: unsymmetric behaviour, compare rows y=15 and y=74
 flat2fish: unsymmetric behaviour, compare rows y=15 and y=74
 flat2dfish: unsymmetric behaviour, compare rows y=15 and y=74
 flat2cyl: unsymmetric behaviour, compare rows y=0 and y=44
 flat2ball: unsymmetric behaviour, compare row y=45 with row y=134, same
 problem also for columns x=45 and x=135

 cyl2ball: unsymmetric behaviour, pixel 81,43 is black but pixel 81,135 is
 magenta
 cyl2dfish: the right circle has larger diameter than the left circle
 cyl2fish: unsymmetric behaviour, pixel 77,29 is red but pixel 77,151 is
 black


 Here are the command lines for the test images and all 36 combinations:

 ffmpeg -f lavfi -i color=black:s=180x90 -lavfi
 geq=r='255*mod(trunc(4*X/W),2)':g='255*trunc(2*X/W)':b='255*trunc(2*Y/H)'
 -frames 1 -y test.png
 ffmpeg -i test.png -lavfi crop=90:90 -y test2.png

 ffmpeg -i test.png -lavfi v360=e:e:h_fov=360:v_fov=180:interp=near -y
 eq2eq.png
 ffmpeg -i test.png -lavfi
 v360=e:flat:h_fov=120:v_fov=120:interp=near -y eq2flat.png
 ffmpeg -i test.png -lavfi v360=e:fisheye:interp=near -y eq2fish.png
 ffmpeg -i test.png -lavfi v360=e:dfisheye:h_fov=180:v_fov=180:interp=near
 -y eq2dfish.png
 ffmpeg -i test.png -lavfi
 v360=e:cylindrical:h_fov=360:v_fov=120:interp=near -y eq2cyl.png
 ffmpeg -i test.png -lavfi v360=e:ball:h_fov=180:v_fov=180:interp=near -y
 eq2ball.png

 ffmpeg -i test.png -lavfi
 v360=flat:e:ih_fov=120:iv_fov=120:h_fov=360:v_fov=180:interp=near -y
 flat2eq.png
 ffmpeg -i test.png -lavfi
 v360=flat:flat:ih_fov=120:iv_fov=120:h_fov=120:v_fov=120:interp=near -y
 flat2flat.png
 ffmpeg -i test.png -lavfi
 v360=flat:fisheye:ih_fov=120:iv_fov=120:interp=near -y flat2fish.png
 ffmpeg -i test.png -lavfi
 v360=flat:dfisheye:ih_fov=120:iv_fov=120:interp=near -y flat2dfish.png
 ffmpeg -i test.png -lavfi
 v360=flat:cylindrical:ih_fov=120:iv_fov=120:h_fov=360:v_fov=120:interp=near
 -y flat2cyl.png
 ffmpeg -i test.png -lavfi v360=flat:ball:ih_fov=120:iv_fov=120:interp=near
 -y flat2ball.png

 ffmpeg -i test2.png -lavfi v360=fisheye:e:interp=near -y fish2eq.png
 ffmpeg -i test2.png -lavfi
 v360=fisheye:flat:h_fov=120:v_fov=120:interp=near -y fish2flat.png
 ffmpeg -i test2.png -lavfi v360=fisheye:fisheye:interp=near -y
 fish2fish.png
 ffmpeg -i test2.png -lavfi v360=fisheye:dfisheye:interp=near -y
 fish2dfish.png
 ffmpeg -i test2.png -lavfi
 v360=fisheye:cylindrical:h_fov=120:v_fov=120:interp=near -y fish2cyl.png
 ffmpeg -i test2.png -lavfi v360=fisheye:ball:interp=near -y fish2ball.png

 ffmpeg -i test.png -lavfi v360=dfisheye:e:interp=near -y dfish2eq.png
 ffmpeg -i test.png -lavfi
 v360=dfisheye:flat:h_fov=120:v_fov=120:interp=near -y dfish2flat.png
 ffmpeg -i test.png -lavfi v360=dfisheye:fisheye:interp=near -y
 dfish2fish.png
 ffmpeg -i test.png -lavfi v360=dfisheye:dfisheye:interp=near -y
 dfish2dfish.png
 ffmpeg -i test.png -lavfi
 v360=dfisheye:cylindrical:h_fov=360:v_fov=120:interp=near -y dfish2cyl.png
 ffmpeg -i test.png -lavfi v360=dfisheye:ball:interp=near -y dfish2ball.png

 ffmpeg -i test.png -lavfi
 v360=cylindrical:e:ih_fov=360:iv_fov=120:interp=near -y cyl2eq.png
 ffmpeg -i test.png -lavfi
 v360=cylindrical:flat:ih_fov=360:iv_fov=120:h_fov=120:v_fov=120:interp=near
 -y cyl2flat.png
 ffmpeg -i test.png -lavfi
 v360=cylindrical:fisheye:ih_fov=360:iv_fov=120:w=180:h=180:interp=near -y
 cyl2fish.png
 ffmpeg -i test.png -lavfi
 v360=cylindrical:dfisheye:ih_fov=360:iv_fov=120:w=180:h=90:interp=near -y
 cyl2dfish.png
 ffmpeg -i test.png -lavfi
 v360=cylindrical:cylindrical:ih_fov=360:iv_fov=120:h_fov=360:v_fov=120:interp=near
 -y cyl2cyl.png
 ffmpeg -i test.png -lavfi
 v360=cylindrical:ball:ih_fov=360:iv_fov=120:w=180:h=180:interp=near -y
 cyl2ball.png

 ffmpeg -i test2.png -lavfi v360=ball:e:interp=near -y ball2eq.png
 ffmpeg -i test2.png -lavfi v360=ball:flat:h_fov=120:v_fov=120:interp=near
 -y ball2flat.png
 ffmpeg -i test2.png -lavfi v360=ball:fisheye:interp=near -y ball2fish.png
 ffmpeg -i test2.png -lavfi v360=ball:dfisheye:interp=near -y
 ball2dfish.png
 ffmpeg -i test2.png -lavfi
 v360=ball:cylindrical:h_fov=360:v_fov=120:interp=near -y ball2cyl.png
 ffmpeg -i test2.png -lavfi v360=ball:ball:interp=near -y ball2ball.png
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Ticket URL: <https://trac.ffmpeg.org/ticket/9617>
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