Thank you Graeme and jys for the detailed responses.
The ffmpeg command that jys provided works well:
ffmpeg -i input.mov \
-vf 'lenscorrection=k2=0.006:k1=-0.18' \
output.mov
(I found by trial and error that a k2 value of 0.006 produces slightly better
results)
jys, could you please elaborate on how you obtained your k1 and k2 values?
Graeme, if a GoPro user opts to edit their footage with ffmpeg + lensfun
instead of GoPro Studio, chances are they’re open to unreasonable suggestions
anyway. In this context, if the end is better quality, any means is justified;
so I do encourage you to update the documentation accordingly :-)
Ariel
> On 17 Mar 2019, at 1:37 pm, Graeme Leese <gnl...@gmail.com> wrote:
>
>
>
> On Sat, 16 Mar 2019, 22:28 jys, <junkyardspar...@yepmail.net
> <mailto:junkyardspar...@yepmail.net>> wrote:
> [...] either because the Hero 6 has a different lens, or because the video is
> already partially corrected (is that what "linear mode" does?)
>
> Googling suggests that the lenses are the same in the 5 and 6 (from a sample
> of one reviewer), so my guess is the data will work for non-linear mode.
>
> I would just use the "lenscorrection" filter:
>
> This seems like a good solution for now. Would it make sense to add a
> calibration for linear mode for the future? I know that we don't normally add
> data for pre-corrected things, but we also don't have a good way of
> communicating to GoPro users that you get better quality by not using linear
> mode if you're going to use lensfun to correct it afterwards. (And I don't
> know whether that's a reasonable suggestion anyway).
>
> Graeme
>
>
> On Sat, Mar 16, 2019, at 12:17, Ariel Elkin wrote:
> > Hello,
> >
> > I’d like to use lensfun to do lens correction on footage from a GoPro HERO
> > 6.
> >
> > Here’s a snapshot from the footage:
> > https://i.imgur.com/0STHMkD.jpg <https://i.imgur.com/0STHMkD.jpg>
> >
> > Even though the footage was shot in linear mode, you can still see as a
> > result of the fisheye lens distortion: the window frame on the left
> > appears curved.
> >
> > Given this sample syntax from the ffmpeg documentation:
> > ffmpeg -i input.mov -vf lensfun=make=Canon:model="Canon EOS
> > 100D":lens_model="Canon EF-S 18-55mm f/3.5-5.6 IS
> > STM":focal_length=18:aperture=8 -c:v h264 -b:v 8000k output.mov
> >
> > I’m not clear what values I should put for make, model, lens_model,
> > focal_length, and aperture. On lensfun lens list I see GoPro and
> > fixed_lens but how exactly should I use that with ffmpeg?
> >
> > Thanks
> >https://www.fastmail.com/mail/traffic.lensfun/?u=156841ae
> ><https://www.fastmail.com/mail/traffic.lensfun/?u=156841ae>
> > Ariel
>
>
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