[FFmpeg-user] Dejudder

Mark Filipak markfilipak.windows+ffmpeg at gmail.com
Fri Feb 7 02:15:28 EET 2020

This is a most important filter. I thoroughly understand judder caused 
by hard-telecine. I understand pulldown. I simply seek clarification of 
the dejudder filter's behavior.

Re: https://ffmpeg.org/ffmpeg-filters.html#dejudder

"If the original source was partially telecined content then the output 
of pullup,dejudder will have a variable frame rate."

What does the author mean by "pullup,dejudder"? That is: Why did the 
author jamb the words together separated by a comma? What is the author 
trying to 'say'?
I suspect that "of pullup,dejudder" would best be left out of the text, 
but I can't know because the current text somewhat mystifies me due to 
errors in language usage.

"May change the recorded frame rate of the container."

Under what specific circumstances?
And (with tongue in cheek) how is the "recorded frame rate of the 
container" changed when the container is on a DVD-ROM? Should the 
sentence read: "Will change the frame rate of the output"?

"Aside from that change, this filter will not affect constant frame rate 

Does that mean,
1, That the dejudder filter is ignored for CFR video (and can thereby be 
specified universally and indiscriminately)? or
2, That dejudder is incapable of changing CFR video?

In other words, why wouldn't I simply always specify "dejudder"?

Is anyone interested in pictures that visually display what telecine & 
pulldown are and what what they do? I have such pictures. They're very 
helpful and work much better than words.

Is anyone interested in me acting as a critical editor for ffmpeg 
documentation? I would function like a book editor by suggesting textual 
changes to improve English language usage and meaning. Of course, all 
suggestions would be subject to approval by the original authors. This 
is a serious offer. My qualifications are as a documentarian and as an 
electronic hardware engineer (retired). Simply put, I'd be another pair 
of eyes, eyes that care.


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