[FFmpeg-user] Upscaling SD 4x3 to FullHD 16x9 - Aspect Ratio problem

[Dragan Randjelovic]

Here is an interesting article:

https://avpres.net/FFmpeg/SD_HD.html

as far as scaling and re-sampling algo goes I would invoke avisynth and try
thin raster  with

    Spline64Resize(1440,1080)

as it usually gives better Y-PSNR metric.

Try also sinc re-sampler and see if it suits your case. Once material is
with a lot of fractal details I get crisper results with it.

I would also consider colorspace matrix compensation for luma coefficients
like

colormatrix=bt601:bt709

and then your padding formula

pad=1920:1080:240:0

Re-interlacing  might not be necessary after all, even if it goes to
play-out.


Kind Regards.
.

On Fri, Jun 22, 2018 at 3:19 PM, Cley Faye <cleyfaye at gmail.com> wrote:

> Le ven. 22 juin 2018 à 15:10, Christoph Gerstbauer <
> christophgerstbauer at gmail.com> a écrit :
>
> > >
> > >
> > > ​The "-s" option is incorrect in your case. From the documentation:
> > > > As an output option, this inserts the scale video filter to the end
> of
> > > the corresponding filtergraph. Please use the scale filter directly to
> > > insert it at the beginning or some other place.​
> > >
> > > The scale video filter will take whatever ends up from your filter, and
> > > scale it without respect to aspect ratio.
> > > To do what you want, you probable have to use a complex filter, where
> you
> > > create a secondary black source and paste the output of your current
> > filter
> > > into it using the "overlay" filter.
> > >
> >
> > I understand
> > So i need to generate (after the cropping and deinterlacing to 720x576
> 50p)
> > a filter syntax (within the videofilter) which transforms the 720x576 4:3
> > content to a pillarbox 1050x576 quare pixel video (with black bars at
> > sides) -> and THIS one I can rescale to HD.
> > Correct?
> >
> > if yes, has anyone more experience with that?
> >
>
> ​Roughly. Look at the other answer; it basically does the pillarbox *after*
> the initlal rescale, which is probably a better idea.​
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