[FFmpeg-user] ffmpeg and use of the ildct flag in progressive encoding

Erik Dobberkau erik.dobberkau at gmail.com
Sun Dec 17 01:01:24 EET 2023

The ildct flag appears only to be making the output file "think" it is
> interlaced, when it is, in fact, progressive. It does not seem to be doing
> anything to change the footage (quality-wise and it's still progressive).
> Since someone other than myself set the flag on this command, I am trying
> to figure out what effect, if any, taking it off will do to the output.
IIRC, it only has an effect when you are creating an interlaced output
using -top 1, (and from here on I‘m guessing) it might instruct the encoder
or an automatically inserted filter to apply the DCT in a different fashion
compared to a progressive input.
But again, that’s a guess which may (also) be outdated, since I last did
these kinds of transcodes quite a while ago.
Good luck.

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