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

[FFmpeg]

#8590: 'telecine=pattern' error for p24, soft telecined sources
-------------------------------------+-------------------------------------
             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            |
-------------------------------------+-------------------------------------

Comment (by pdr0):

 Replying to [comment:8 markfilipak]:
 >
 >
 > Well, Richard, you can see it for yourself.
 > ffmpeg -i IN.M2TS -vf "telecine=pattern=5555,bwdif=mode=send_frame"
 -avoid_negative_ts 1 -c:v libx265 -crf 20 -preset medium -c:a copy -c:s
 copy OUT.MKV
 >
 > It works wonderfully for BD content, but not soft-telecined DVD content
 due to the design of 'telecine'.
 >
 > With 2-3-2-3 pull-down, 2 of 5 frames are combed and the combed frames
 adjoin.
 > With 5-5-5-5 pull-down, only 2 of 10 frames are combed and the combed
 frames are separated by 4 progressive frames.
 >
 > In other words, there's no noticable judder and decombing is not needed
 due to the 1/60th second duration of the combed frame.
 >
 > In other words, 'telecine=pattern=5555' works as advertised for BDs, but
 not for DVDs. Now, why would that be, eh?




 I tested this on a native 24.0p blu ray

 The end result is hardcoding duplicate frames in a progressive 3:2
 pattern. The output file fps is 60.0 CFR. There is no combing when
 examining the elementary output stream.

 Examine the actual file (actual encoded frames),  and their
 timecodes(timestamps). The average frame display time is 16-17ms (it
 fluctuates between 16,17 because of container timebase rounding), because
 it's 60.0 CFR. (1/60 = ~16.6667 ms per frame)

 There is no visual cadence difference between this and doing nothing on a
 60Hz display. You are just encoding 2.5x more frames for nothing (slower,
 lower quality at a given bitrate)


 I repeated it on a native 23.976p blu ray. Same thing, no combing, 3:2
 progressive repeats. Just 59.94 instead of 60.0

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Ticket URL: <https://trac.ffmpeg.org/ticket/8590#comment:11>
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