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

Nik Armstrong nik.a at smpstaff.org
Sun Dec 17 21:44:36 EET 2023

On 2023-12-16 15:01, Erik Dobberkau wrote:
> 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 But again, that’s a guess which may (also) be outdated, since I last 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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Thanks Erik. Much appreciated.

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