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

[Mark Filipak]

On 29/05/2025 00.30, Alex Xu wrote:
> I tried running your exact command and got the same result. Dropped frame
> 173 and a later duplicated frame.
> 
> I've attached 15 frames here of the results.
> 
> https://drive.google.com/drive/folders/139rjLqsxIuAO_3yzVNe4dD7-gI9YPRgn?usp=drive_link
> 
> I've attached 5 frames each of the original input, using detelecine, and
> using fieldmatch+decimate with your command.

Thanks for those pictures. They make this a little easier.

First, some preparation:

This section of detelecine is:
[Cd][Dd][Aa][Bb][Bc] -> [Cc][Dd][Aa][Bb]

 From input.mkv:
Frame 215 @ 7.174  =input-0001.png [Cd]
Frame 216 @ 7.207  =input-0002.png [Dd]
Frame 217 @ 7.241  =input-0003.png [Aa]
Frame 218 @ 7.274  =input-0004.png [Bb]
Frame 219 @ 7.307  =input-0005.png [Bc]

Now, the results:

ffmpeg^
  -i input.mkv^
  -vf fieldmatch,decimate^
  -c:a aac^
  -c:v libx264^
  output.mkv

Honestly, from the command line above, I'm getting
exactly what you got using 'detelecine'. Look:

Frame 172 @ 7.174  =detelecine1.png [Cc]
Frame 173 @ 7.215  =detelecine2.png [Dd]
Frame 174 @ 7.257  =detelecine3.png [Aa]
Frame 175 @ 7.299  =detelecine4.png [Bb]

No missing frame, no repeated frame.

I have no idea why your FFmpeg is different.