[FFmpeg-devel] Vignette filter limitations...

[Paul B Mahol]

On 8/27/17, Evert Vorster <evorster at gmail.com> wrote:
> Hi there.

Hi,

>
> I have asked this question on the ffmpeg-users list, but it's been oddly
> quiet on this front.
>
> I am trying to create a ffmpeg command line that re-maps and stitches
> together footage from the Samsung Gear 360 camera. The basic methodoly can
> be applied to any 360 view camera. The reason I am doing this is that the
> software that is available to do this is closed source and extremely
> expensive. For a hobbiest, this is a bad situation.
>
> First thing I do, is to load a specially crafted series of frames in Hugin,
> and perfectly map the lenses.
> Then I make the remap files that the ffmpeg remap filter uses with nona -c.
> I hand craft a alpha map to do the blending between the lenses, and the
> results are really good.
>
> Unfortunately I have a real problem with vignetting.
> The vignette filter in ffmpeg seems to have some room for improvement.
> In Ffmpeg there is only one variable, and the x,y center. This allows for
> only one type of vignetting correction with the "backward" option set.
>
> In Hugin (and the panotools) the lens is described with 3 variables, and an
> x,y center. This enables the vignetting strength to be described as a
> custom curve.
>
> If you are curious about the project, this is the github page, with
> examples.
> https://github.com/evertvorster/dualfisheye2equirectangular_ffmpeg_remap
> There are example .pto files, that when loaded in Hugin show the lens
> chataristics of the Samsung Gear 360 lenses, and some sample footage to
> test on.
>
> How difficult would it be to port the panotools' vignetting correcting
> filter into ffmpeg?

How it is actually named?