[FFmpeg-user] simple bob -- How?

Paul B Mahol onemda at gmail.com
Tue Dec 29 11:28:15 EET 2020


On Tue, Dec 29, 2020 at 10:13 AM Mark Filipak (ffmpeg) <markfilipak at bog.us>
wrote:

> On 12/29/2020 04:04 AM, Paul B Mahol wrote:
> > On Tue, Dec 29, 2020 at 9:56 AM Mark Filipak (ffmpeg) <
> markfilipak at bog.us>
> > wrote:
> >
> >> On 12/29/2020 03:41 AM, Paul B Mahol wrote:
> >>> On Tue, Dec 29, 2020 at 5:51 AM Mark Filipak (ffmpeg) <
> >> markfilipak at bog.us>
> >>> wrote:
> >>>
> >>>> I seek a way to do simple bob (i.e. repeat fields at 2xFPS) with no
> >> other
> >>>> filtering. Can you help me?
> >>>>
> >>>> I suppose I could do something like this:
> >>>> -filter_complex
> >>>>
> >>>>
> >>
> "split[s1][s2],[s1]separatefields[A1][a1],[s2]separatefields[A2][a2],[A1][A2]weave[Ao],[a1][a2]weave[ao],[Ao][ao]merge"
> >>>> (Kindly forgive any mistakes -- I haven't done anything like this in a
> >>>> couple of months.)
> >>>> But I thought I'd ask here for an easier way.
> >>>>
> >>>> These gave pretty good results. They're listed from best to worst:
> >>>> bwdif
> >>>> yadif=send_field_nospatial
> >>>> yadif=send_field
> >>>>
> >>>> However, I suspect that, in addition to mechanical frame changes,
> >> they're
> >>>> also making some
> >>>> (unwanted) cosmetic changes.
> >>>>
> >>>> Based on what's written in the documention, these seemed promising:
> >>>> separatefields,doubleweave
> >>>> separatefields,tinterlace=mergex2
> >>>>
> >>>> But they produced surprising and undesired results.
> >>>>
> >>>> Optional Reading:
> >>>>
> >>>> I also tried this:
> >>>>
> >>>> separatefields,select=eq(mod(n,4),0)+eq(mod(n,4),3),weave
> >>>>
> >>>> It's not what I actually want, but I tried it because it doesn't make
> >>>> sense to me -- weave together
> >>>> fields N%4==0 and N%4==3? (Really? Modulo-4? fields 0 & 3?) -- so,
> >> because
> >>>> it doesn't make sense to
> >>>> me, I thought I might learn something interesting. So, what happened?
> >>>> "Conversion failed!" is what
> >>>> happened. Why it's cited as an example (
> >>>> https://ffmpeg.org/ffmpeg-filters.html#Examples-121) in the
> >>>> documentation is a mystery to me.
> >>>>
> >>>
> >>> After so much time you still struggle a lot, buy some GUI tools and be
> >>> happy ever after.
> >>
> >> You're not helping, Paul.
> >>
> >
> > I'm helping you so you can help yourself.
> >
> >
> >>
> >>> You probably missing \ to escape every , inside expressions.
> >>
> >> I'm running in Windows.
> >>
> >
> > That is not important. Either escape ',' inside expressions or do not ask
> > for help if you gonna ignore help.
>
> Ah! "inside expressions". Sorry. Yes, I '\,' inside expressions. I'm not
> using any expressions.
>

Looks like there is very big language/logic gap between us.

Try this:

"separatefields,select=eq(mod(n\,4)\,0)+eq(mod(n\,4)\,3),weave"



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