[FFmpeg-user] Pullup filter is introducing chroma lag

[llee040]

> On Mar 8, 2022, at 11:32 AM, morgan holly via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
> 
> Hi,
> 
> I’m trying to remove telecine from a prores mov file using the pullup filter:
> 
> Source file:
> Video: prores (LT), top coded first (swapped)), 720x480, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
> 
> Command:
> ffmpeg -i pullup_test.mov -an -vf pullup -r 24000/1001 -pix_fmt yuv420p -y pullup_test1.mov
> 
> Result:
> Every fourth frame on the 23.976 output has chroma lag (3/2 removed from luma, but chroma is still interlaced). Dejudder doesn’t fix it and fieldmatch+decimate does worse things.
> 
> Test sources:
> I’ve seen the artifact on both live action and clean animation sources. I cannot share the sources but created a short example that can be used to recreate the issue:
> 
> Test source with 3/2:
> http://videopress.s3.amazonaws.com/misc/pullup_test.mov <http://videopress.s3.amazonaws.com/misc/pullup_test.mov>
> 
> Test pullup 23.976 output:
> http://videopress.s3.amazonaws.com/misc/pullup_test_1.mov <http://videopress.s3.amazonaws.com/misc/pullup_test_1.mov>
> 
> Thanks for any help!
> 

Not sure if this will help but it seemed to create slightly better output for your test movie when substituted for “pullup”:

detelecine=first_field=b:start_frame=0,yadif=deint=interlaced

ffmpeg -i pullup_test.mov -an -vf detelecine=first_field=b:start_frame=0,yadif=deint=interlaced -r 24000/1001 -pix_fmt yuv420p -y pullup_test1.mov

L. Lee