[FFmpeg-user] Detelecine: I got the right result from the wrong command?

[Richard Bartczak]

Am 17.05.25 um 06:03 schrieb Alex Xu:
> Hi everyone,
>
> I'm working to detelecine a video, attached here (12 MB, first 32 seconds
> truncated):
> https://www.mediafire.com/file/x4ly6moqb8ayfyy/detelecine_input.mkv/file
>
> I wasn't sure what was the right command to get the result I wanted so I
> looped over all possible combos like so:
>
> for i in 0 1 2 3 4; do
> for j in 23 2332; do
> ffmpeg -i detelecine_input.mkv -c:v libx264 -crf 18 -c:a aac -b:a 192k
> -pix_fmt yuv420p -vf "detelecine=start_frame=$i:pattern=$j"  $i$j.mkv;
> done
> done
>
> It was very clear which option was correct, since the correct option
> encoded the best and had a significantly smaller file size. I visually
> verified it too. In the source, every set of 5 frames had 3 clear frames
> and 2 interleaved frames. In the final output, it preserved those 3 clear
> frames and combines the 2 interleaved frames into 1, going from 30i to 24p.
>
> But I'm just not sure why the correct result was start_frame=3:pattern=2332.
>
> Examining the video, it seems pretty clear to me the pattern should be 23.
> Since it has two interleaved frames. I learned about 23 from
> https://en.wikipedia.org/wiki/Telecine#2:3_pulldown
>
> Could someone explain the gap in my knowledge?
>
> Alex
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If you want to get the progressive mode :

ffmpeg -i "interlacevideo.mkv" -vcodec libx264 -crf 18 -preset slow -vf 
yadif -c:a copy "progressivevideo.mkv"

Richard