[FFmpeg-trac] #9316(undetermined:new): nnedi af mode causes flicker at top and bottom row

FFmpeg trac at avcodec.org
Sun Jul 4 16:40:50 EEST 2021


#9316: nnedi af mode causes flicker at top and bottom row
-------------------------------------+-------------------------------------
             Reporter:  Tom B        |                    Owner:  (none)
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Description changed by Tom B:

Old description:

> I'm using the following filter:
>
> -vf nnedi=weights.bin:all:af
>
> This generally works great, however, when converting 50i to 50p footage
> it causes a flicker at the top and bottom field in most frames.
>
> It seems that odd frames are simply black. It would be good if it used a
> bob/weave here as the result is distracting. yadif=1 produces worse
> results overall (e.g. scrolling text looks horrible) but does not produce
> this same flicker.
>
> This doesn't just happen on PAL videos like this with a black half row at
> the top/bottom. It happens on any video when `af` is specified.
>
> Using `a` mode works fine but obviously drops 50% of frames.

New description:

 I'm using the following filter:

 -vf nnedi=weights.bin:all:af

 This generally works great, however, when converting 50i to 50p footage it
 causes a flicker at the top and bottom field in most frames.

 It seems that odd frames are simply black. It would be good if it used a
 bob/weave here as the result is distracting. yadif=1 produces worse
 results overall (e.g. scrolling text looks horrible) but does not produce
 this same flicker.

 This doesn't just happen on PAL videos like this with a black half row at
 the top/bottom. It happens on any video when `af` is specified.

 Using `a` mode works fine but obviously drops 50% of frames.


 I hadn't realised that the attachment limit was 2.5mb on here. Here are
 the videos:

 Original video https://r.je/tmp/original.mkv

 -vf nnedi=weights.bin:all:af https://r.je/tmp/nnedi.mkv

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Ticket URL: <https://trac.ffmpeg.org/ticket/9316#comment:1>
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