[FFmpeg-user] stereo images conversion changes aspect ratio

[Tom Sparks]

I am converting a stereo images that top/bottom to left/right

I am using this command
./ffmpeg -i "elphelimg_2421643.jpg" -qscale 1 -vf 'mp=down3dright' "output.jpg"

here is the source imge
http://www.lightningridgecommunity.com/panorama/elphelimg_2421643.jpeg

here is the result image
http://www.lightningridgecommunity.com/panorama/output.jpg

As you can see the circle have changed into ovals, is there any way to stop this from happening?

--
tom_a_sparks "It's a nerdy thing I like to do"
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