[FFmpeg-user] Specific interlacing issue

[Ivo Noorlander]

Hi there

I run into an issue with the interlaced output of concatenated sources. 

ffmpeg -i colours.mov -vf telecine=pattern=223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322223222232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323,setfield=tff "-r" "30000/1001" "-pix_fmt" "yuv422p10le" "-c:v" "prores_ks" "-profile:v" "3" "-vendor" "apl0" "-flags" "+ilme+ildct" -top 1 -an colours_pulldown.mov

This command creates a 29.97i version of a 25p source with pulldown that keeps the same length in 29.97. When a cut lands on the split frame, the top field is the shot before the cut and the bottom field the shot after the cut as checked by
ffmpeg -ss 0.3003 -i colours_pulldown.mov -frames 1 -vf field=top top.png;ffmpeg -ss 0.3003 -i colours_pulldown.mov -frames 1 -vf field=bottom bottom.png

However when another source processed before the pulldown, the resulting output has interleaved fields. The cuts that are on the split frame now have lines from one another which shows as colour casts, as can be seen when extracting the top.png and bottom.png.

The command for concatenating the sources was

ffmpeg -f lavfi -i smptebars=s=1920x1080:r=60000/1001:d=5 -i colours.mov -filter_complex "[0]interlace[int];[int]setfield=tff[v1];[1]telecine=pattern=223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322223222232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323223232232322323[telecine];[telecine]setfield=tff[v2];[v1][v2]concat=n=2:v=1:a=0[v]" -map "[v]" -pix_fmt yuv422p10le -r 30000/1001 -c:v prores_ks -profile:v 3 -vendor apl0 -flags +ilme+ildct -top 1 -an -y colours_pulldown.mov

Adding the -field_order tt command does not change this.

Is this a prores_ks issue or am I not understanding interlacing correcty?

Hope you can help

Thanks
Ivo