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Re: Help with video editing with ffmpeg




For the record, here's the thread on ffmpeg-user mailing list:
http://ffmpeg.org/pipermail/ffmpeg-user/2019-March/043677.html

Gerardo




Il giorno mer 6 mar 2019 alle ore 11:48 Gerardo Ballabio
<gerardo.ballabio@xxxxxxxxx> ha scritto:
>
> I guess my question was too specific. I'll try asking directly on
> ffmpeg mailing list.
> Thanks
> Gerardo
>
>
> Il giorno dom 3 mar 2019 alle ore 18:16 Gerardo Ballabio
> <gerardo.ballabio@xxxxxxxxx> ha scritto:
> >
> > Hello all,
> > I have a video that was filmed under bad lighting conditions, the
> > background is too bright and people in the foreground are dark. I'm
> > trying to use ffmpeg to correct it. Please kindly help me.
> >
> > Here you can find a snippet:
> > https://drive.google.com/drive/folders/1aG04znyHdDio7cvgaQlovYTb8bX8NTLL?usp=sharing
> >
> > video1.mts is the original file. video2.mp4 was created by a friend of
> > mine using proprietary software on Windows. I've been trying to
> > reproduce that. video3.mts is the best result I obtained (see below)
> > but the contrast is still too high and the colors aren't quite right.
> >
> > I've tried several of ffmpeg's effects but maybe there are some better
> > ones that I missed?
> >
> > - "eq=brightness=..." turns black into grey and gives the video a
> > "foggy" look, no good
> > - "colorlevels=..." I tried many parameter sets but couldn't do much
> > better, in the end I concluded that probably linear scaling isn't good
> > enough and I need nonlinear
> > - "curves=..." was indeed better but when I stretched the curve beyond
> > a certain point I obtained distorted colors
> > - I tried "geq=..." too but it doesn't seem to work, I always get an
> > error like this:
> >
> > ffmpeg -i video1.mts -vf geq='r=r(X,Y):g=g(X,Y):b=b(X,Y)' video3.mts
> > [Parsed_geq_0 @ 0x55a01bb0aa60] [Eval @ 0x7ffd3d63afb0] Missing ')' or
> > too many args in 'r(X'
> > [AVFilterGraph @ 0x55a01bb09e80] Error initializing filter 'geq' with
> > args 'r=r(X'
> > Error opening filters!
> >
> > These are the commands that I used to produce video3.mts:
> >
> > ffmpeg -i video1.mts -vf colorlevels=romax=0.8:gomax=1.0:bomax=0.9 -b
> > 12M temp.mts
> > ffmpeg -i temp.mts -vf curves=r='0/0.05 0.1/0.25 1/0.8':g='0/0.05
> > 0.1/0.25 1/0.8':b='0/0.05 0.1/0.25 1/0.8' -b 12M video3.mts
> >
> > Thanks
> > Gerardo