[FFmpeg-user] -pix_fmt yuv420p and deinterlacing

Carl Eugen Hoyos ceffmpeg at gmail.com
Sun Feb 26 13:19:08 EET 2017

2017-02-26 12:11 GMT+01:00 Katherine Frances <knfrances at gmail.com>:
> Thanks again, Andy.
> So if I understand correctly:
>    1.  *-vf scale=interl=1* registers to libx264 that the input is
>    interlaced and to be 'aware' of that in future operations.

No, the option is meant to tell the scale filter that it has to
adapt its operations for interlaced content.

> *yadif*, of course, does the actual deinterlacing.


>    2. If used in the same script, *scale* must precede *yadif. *Although it
>    seems rather redundant.

I would suggest the opposite since giving yadif more information could
help. There may be a performance trade-off though.

>    3. If deinterlacing with *yadif*, *yadif* should precede chroma
>    downsampling

Same reasoning as above.

> (via *-pix_fmt yuv420p*)

You should not use a (non-trivial) filter-chain and -pix_fmt since
iirc, the output (the filter order) is not defined. (But it is a bad idea

"Scaling" and "Chroma-downsampling" are the same insofar as
they are both done by the scale filter.

Did you already tell us if the content you see is actually interlaced?

As said, please find out what top-posting means and avoid it

Carl Eugen

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