[FFmpeg-user] DOWN CONVERSION ISSUE: From MXF (1080i AVC Intra) - MBAFF "interlacing" to DVCPRO

[Iban Garcia]

2012/3/26 Tim Nicholson <nichot20 at yahoo.com>

> On 26/03/12 15:29, Iban Garcia wrote:
> > Exact!!
> >
> > But the issue *has been solved* using next:
> >  -vf "scale=720:576:interl=1,fieldorder=tff" -vcodec dvvideo
> >
>
> Ahh, the difference between scale=720:576:1 and scale=720:576:interl=1 !!
>
> I think the documentation is unclear on the fact that for width and height
> you
> just specify an expression, but for interlace you need to specify the
> parameter
> as well.
>
> *But* your command, as above is setting the output field order to tff when
> DV is
> bff so you will get motion judder. I really think you should use:-
>
> ...vf "setfield=1, scale=720:576:interl=1, fieldorder=bff"...
>
> or:-
>
> -vf "setfield=0, scale=720:576:interl=1"...
> if your source is already bottom field first (unlikely).
>
> Umm... it is strange, because if I use
-vf "setfield=1, scale=720:576:interl=1, fieldorder=bff"
I get incorrect field order when playing (motion judder)
The only way I have got the video correctly played is using "tff" instead
of "bff".


>
> > I think ffmpeg should "detect" the interlaced without "interl=1" option.
> >
>
> That option has nothing to do with detection, its how the scaling filter
> should
> work.
>
> ffmpeg *can* detect interlace for which you set interl=-1 to let the filter
> decide automatically how to behave, however by default I believe it is set
> to 0,
> i.e off.
>
> *However* as I mentioned previously. MXF material seems to be always
> detected as
> progressive even when it is not. It is not just ffmpeg that makes this
> mistake.
> The way you detect interlace in MXF seems to be different to most other
> formats.
> Hence the forcing of the interlace flag by setfield, followed by telling
> the
> scaler to use interlaced scaling.
>
> Understood. Thanks Tim.


> > Many thanks, Tim!!!
> >
> >
> > 2012/3/26 Tim Nicholson <nichot20 at yahoo.com>
> >
> >> On 26/03/12 11:34, Iban Garcia wrote:
> >>> Umm... it does not work for me. The output.dv is still "progressive"
> >>> (de-interlaced): both fields of output.dv file are equal. The
> interlacing
> >>> has been lost...
> >>>
> >>
> >> OK so something is not working as it should. I have had a look at some
> of
> >> my
> >> H264 10bit interlaced material and that is also behaving as you
> describe.
> >> The
> >> source is definitely interlaced, as can be seen from the interlace
> >> artifacts in
> >> a resized ffplay window. But the output is a blend of the two fields.
> >>
> >> I will try and get some more details and then raise a bug report.
> >>
> >>> I have download and installed "ffmbc". I am doing some test now with
> it.
> >>> But, by the moment, all of the tests has the same "de-interlaced"
> >> output...
> >>> :-(((
> >>>
> >>>
> >>> 2012/3/26 Tim Nicholson <nichot20 at yahoo.com>
> >>>
> >>>> On 25/03/12 15:43, Iban Garcia wrote:
> >>>>> Hi,
> >>>>>
> >>>>> I have taken from git the last version of ffmpeg. And I have made
> next
> >>>>> test. The output.dv fields are not interlaced. The interlaced
> >> information
> >>>>> has been lost in the process.
> >>>>>
> >>>>> # ffmpeg -y -threads 8 -i input.mxf -s 720x576 -pix_fmt yuv411p
> -aspect
> >>>>> 16:9 -an -r 25 -vf "setfield=1, fieldorder=bff" output.dv
> >>>>
> >>>>> [..]
> >>>>
> >>>>> sws_param:
> >>>>> [fieldorder @ 0x646e80] output field order: bff
> >>>>> [scale @ 0x6283a0] w:1920 h:1080 fmt:yuv422p10le sar:1/1 -> w:720
> h:576
> >>>>> fmt:yuv411p sar:64/45 flags:0x4
> >>>>>
> >>>>
> >>>> As your source is HD and you wish to output SD, you should really
> scale
> >> the
> >>>> material properly using the "scale" filter with interlacing turned on.
> >>>>
> >>>> Something like:-
> >>>>
> >>>> ffmpeg -y -threads 8 -i input.mxf \
> >>>> -vf "setfield=1, scale=720:576:1, fieldorder=bff" \
> >>>> -pix_fmt yuv411p -aspect 16:9 -an -r 25 output.dv
> >>>>
> >>>> --
> >>>> Tim
> >>>> _______________________________________________
> >>
> >> --
> >> Tim
> >> _______________________________________________
> >> ffmpeg-user mailing list
> >> ffmpeg-user at ffmpeg.org
> >> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >>
> > _______________________________________________
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> >
>
>
> --
> Tim
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