[FFmpeg-user] Wanted: Fields-to-frames filter that does not add cosmetics

[Mark Filipak (ffmpeg)]

On 2021-03-05 10:35, pdr0 wrote:
> Mark Filipak (ffmpeg) wrote
>> 'yadif=mode=send_field' is one way to convert fields to frames at the same
>> frame size and twice the
>> FR. It does it by repeating fields, but it also adds cosmetics -- it is,
>> after all, a motion
>> interpolation filter.
>>
>> I seek a fields-to-frames filter that does not add cosmetics. In my
>> pursuit, I look for such a
>> filter every time I peruse the filter docs for anything. I've yet to find
>> such a filter.
>>
>> Do you know of a fields-to-frames filter that does not add cosmetics?
> 
> Yadif is not a motion interpolation filter

Okay, not motion interpolation. My bad. I remember "motion adaptive" being used to describe what 
yadif does. And there's this: http://avisynth.nl/index.php/Yadif
"...by Michael Niedermayer. It check pixels of previous, current and next frames to re-create the 
missed field by some local adaptive method (edge-directed interpolation) and uses spatial check to 
prevent most artifacts."

I need line doubling that, as its bottom field, simply duplicates the top field.

[A+b] ==> [A+A]   ...if a [b+b] frame is also produced, I'll throw it away.

I know of several ways to do it with a series of filters but they take extra time. A simple, 
dedicated line double would be fast and just what I need.

The filter will be applied to a single frame that's isolated via modulo selection.