[FFmpeg-trac] #8590(undetermined:closed): 'telecine=pattern' error for p24, soft telecined sources

[FFmpeg]

#8590: 'telecine=pattern' error for p24, soft telecined sources
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             Reporter:  markfilipak  |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:  invalid
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by pdr0):

 Replying to [comment:35 markfilipak]:
 >


 >
 > I do some technical writing. I'd appreciate your opinion of the
 following
 >
 > "Twitter is when finely textured areas such as ventilation grates, brick
 walls, and textured paper appear to rapidly flash on-off-on-off or to
 flash changing colors. Twitter can make an actor's face appear to pulsate
 during close-ups. Twitter is actually a milder case of combing, but over
 an area. For uniformly patterned surfaces, twitter can produce moire."
 >
 > I'm not sure that twitter applies to faces appearing to pulsate.


 The face part isn't a good example, because faces are more organic and
 have curved lines and tend to hide those types of artifacts with the
 exception of the eyelids (straight line).

 Twitter can be described in terms of sampling theory and nyquist theorem.
 It's aliasing artifacts, when viewed in motion. It boils down to
 undersampling. Essentially gaps in information, which are more easily
 identified in things such as straight lines , and that's what twitter
 usually refers to (lines, edges).  In layman' s terms it looks likes jaggy
 buzzing lines. (Of course you can get "jaggy buzzing lines" from other
 things too, such as compression artifacts, but twitter has a
 characteristic look)


 >
 > Meaning: The 24fps video you made, right? That's a good source for
 testing aspects of transcoding animations, but I wonder how applicable it
 is to analog movies. 5-5-5-5 seems to work wonderfully for movies. This
 brings up a bushel basket of issues.
 >


 Yes, it's a synthetic high contrast test, but it's still predictive of the
 issues you see on real content. Real content will typically also have
 motion blur, so the effect can be reduced somewhat

 Go test it out. I can see the combing when on trying this on a BD. Yes,
 certain scenes and types of content hide it well. On others it sticks out
 like a sore thumb.  You have a nice high quality progressive BD, and now
 there is combing artifacts, sometimes everywhere, across the whole screen,
 not just limited to a tiny "text" area. But it's there and you can see it.
 It's terrible in my opinion, even worse than blends. It's so distracting
 that it ruins the viewing experience - not a hyperbole.

 Some types of displays might have additional processing and decomb it, so
 you might not see it. My living room TV is 120Hz, but the computer monitor
 I'm testing this on is 60Hz and I have everything set to to play
 progressive, no processing. It looks bad. You said you hated the judder,
 so maybe it's an acceptable compromise for you



 > I'd like to contribute but have been frustrated.

 Same. Frustrated at times too...

 1) Often programmers seem like a different breed....But there are many
 different types of people in the world. Learn to live with it.

 2) There is a certain decorum or way of expected behaviour on certain
 boards and forums. Observe and learn what is expected before you
 contribute

 3) Don't stop trying to contribute. That's how you improve open source
 projects.

 4) If you keep getting stonewalled, try a different approach, frame it
 slightly differently, or provide more facts and evidence, try to build a
 more convincing case.

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Ticket URL: <https://trac.ffmpeg.org/ticket/8590#comment:36>
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