[FFmpeg-devel] [PATCH]lavfi/telecine: Mark telecined frames as interlaced

[Kieran Kunhya]

On Sun, 12 Apr 2020 at 14:41, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> Am So., 12. Apr. 2020 um 15:16 Uhr schrieb Paul B Mahol <onemda at gmail.com
> >:
> >
> > On 4/12/20, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> > > Am So., 12. Apr. 2020 um 15:00 Uhr schrieb Paul B Mahol <
> onemda at gmail.com>:
> > >>
> > >> On 4/12/20, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> > >> > Am So., 12. Apr. 2020 um 11:35 Uhr schrieb Paul B Mahol
> > >> > <onemda at gmail.com>:
> > >> >>
> > >> >> On 4/12/20, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> > >> >> > Am So., 12. Apr. 2020 um 10:38 Uhr schrieb Paul B Mahol
> > >> >> > <onemda at gmail.com>:
> > >> >> >>
> > >> >> >> On 4/11/20, Paul B Mahol <onemda at gmail.com> wrote:
> > >> >> >> > On 4/11/20, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> > >> >> >> >> Am Sa., 11. Apr. 2020 um 15:10 Uhr schrieb Paul B Mahol
> > >> >> >> >> <onemda at gmail.com>:
> > >> >> >> >>>
> > >> >> >> >>> On 4/11/20, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> > >> >> >> >>> > Am So., 5. Apr. 2020 um 02:05 Uhr schrieb Carl Eugen Hoyos
> > >> >> >> >>> > <ceffmpeg at gmail.com>:
> > >> >> >> >>> >>
> > >> >> >> >>> >> Am So., 5. Apr. 2020 um 01:02 Uhr schrieb Carl Eugen
> Hoyos
> > >> >> >> >>> >> <ceffmpeg at gmail.com>:
> > >> >> >> >>> >> >
> > >> >> >> >>> >> > Am Sa., 4. Apr. 2020 um 00:44 Uhr schrieb Carl Eugen
> Hoyos
> > >> >> >> >>> >> > <ceffmpeg at gmail.com>:
> > >> >> >> >>> >> > >
> > >> >> >> >>> >> > > Am Sa., 4. Apr. 2020 um 00:40 Uhr schrieb James Almer
> > >> >> >> >>> >> > > <jamrial at gmail.com>:
> > >> >> >> >>> >> > > >
> > >> >> >> >>> >> > > > On 4/3/2020 6:37 PM, Carl Eugen Hoyos wrote:
> > >> >> >> >>> >> > > > > Am Fr., 3. Apr. 2020 um 23:19 Uhr schrieb Carl
> Eugen
> > >> >> >> >>> >> > > > > Hoyos
> > >> >> >> >>> >> > > > > <ceffmpeg at gmail.com>:
> > >> >> >> >>> >> > > > >
> > >> >> >> >>> >> > > > >> Attached patch marks actually telecined frames
> as
> > >> >> >> >>> >> > > > >> interlaced,
> > >> >> >> >>> >> > > > >> other frames as progressive.
> > >> >> >> >>> >> > > > >
> > >> >> >> >>> >> > > > > New patch with changes to fate attached.
> > >> >> >> >>> >> > > > >
> > >> >> >> >>> >> > > > > Please comment, Carl Eugen
> > >> >> >> >>> >> > > >
> > >> >> >> >>> >> > > > Those yadif tests look wrong. The patch shouldn't
> > >> >> >> >>> >> > > > affect
> > >> >> >> >>> >> > > > them.
> > >> >> >> >>> >> > >
> > >> >> >> >>> >> > > Clearly, thank you!
> > >> >> >> >>> >> > >
> > >> >> >> >>> >> > > New patch attached, it should now only change the
> > >> >> >> >>> >> > > telecined
> > >> >> >> >>> >> > > frames and leave the other frames as they are, the
> > >> >> >> >>> >> > > setfield
> > >> >> >> >>> >> > > filter can be used to force a progressive setting for
> > >> >> >> >>> >> > > them.
> > >> >> >> >>> >> >
> > >> >> >> >>> >> > New patch attached that also sets top_field_first
> > >> >> >> >>> >>
> > >> >> >> >>> >> Which had the effect that fate is correct again, new
> patch
> > >> >> >> >>> >> attached.
> > >> >> >> >>> >
> > >> >> >> >>> > Patch applied.
> > >> >> >> >>> >
> > >> >> >> >>>
> > >> >> >> >>> This was never approved by me.
> > >> >> >> >>
> > >> >> >> >> You reviewed it on irc and correctly pointed out the missing
> > >> >> >> >> bits.
> > >> >> >> >
> > >> >> >> > Lies, I was against that idea from start.
> > >> >> >> >
> > >> >> >> >>
> > >> >> >> >>> So revert it ASAP!
> > >> >> >> >>
> > >> >> >> >> What should be changed about it?
> > >> >> >> >
> > >> >> >> > Return of code as it was before this pointless change.
> > >> >> >> > I see no good out of it.
> > >> >> >>
> > >> >> >> I gonna revert this ASAP!
> > >> >> >
> > >> >> > Could you explain why it is wrong to mark interlaced frames
> > >> >> > as interlaced?
> > >> >>
> > >> >> The frames are not interlaced.
> > >> >
> > >> > Using the usual 3:2 telecine, the filter outputs two progressive
> > >> > frames, followed by three interlaced frames, the patch should
> > >> > mark the interlaced frames as interlaced and I believe it does.
> > >>
> > >> You are very ignorant or very stupid or both.
> > >
> > > Apparently yes because ...
> > >
> > >> Interlaced frames are frames produced by interlacing.
> > >> Telecine is not interlacing.
> > >
> > > ... to the best of my knowledge, the telecine process outputs
> > > interlaced (and non-interlaced) frames, so I do not understand
> > > your argumentation, please elaborate.
> >
> > Interlacing usually destroys half of data, telecine never does that.
>
> There are cameras that output interlaced content, they do not
> destroy any data (the "missing" data never existed).
>
> I don't think your definition is ideal, a more useful definition is that
> the fields of one frame originate from different points in time.
>
> > Claiming frames are interlaced will just confuse confused users more.
>
> I was more thinking of encoders, they will be less confused with the
> patch.
>
> > >> >> I thought you knew that interlacing destroys half of data.
> > >> >> Telecine does not destroys data.
> > >> >
> > >> > Telecine duplicates some data, leading to interlaced frames.
> > >> > A (perfect) detecine process can remove the duplicated data
> > >> > (and the interlaced frames).
>

You both seem to misunderstand, confusing the structure of the frame with
the transport.

Telecine is a method of taking progressive content (e.g film) and
displaying it on an interlaced device (e.g CRT)
By definition it converts progressive structured frames to interlaced
transport.
This means that all output frames are interlaced (otherwise a CRT would not
be able to play it).
It might so happen that some (or all) frames still retain a progressive
structure but this is orthogonal to the conversion that has taken place.

Regards,
Kieran Kunhya