[FFmpeg-devel] IVTC Using fieldmatch and decimate filters

[Steve Boyer]

Hey all,

I'm trying to encode a video, but not having luck doing a proper IVTC. I
have compiled from source this afternoon as outlined on
https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu. Using the command:

ffmpeg -i 4.17.vob -map 0:1 -map 0:3 -vf crop=704:480:10:0 -vf
fieldmatch,decimate -c:v libx264 -preset veryfast -level 41 -crf 22 -c:a
libfdk_aac -t 360 4.17.mp4

I result in a proper IVTC'ed video stream, but the video seems to go at an
incorrect framerate (although running "ffmpeg -i 4.17.mp4" shows it at a
23.976 fps). I did other versions (using -vf fieldmatch, -vf yadif, -vf
pullup,fps=24000/1001, or -vf pullup -r 24000/1001) and the audio track
remains in sync with the video consistently. Adding the decimate filter in
to the mix seems to make the video play faster than the audio leading to
the desynchronization. I see that https://trac.ffmpeg.org/ticket/3019 has
this as fixed, but I'm still experiencing it.

Honestly, a good IVTC solution is the ONLY thing I miss from Windows.

I can provide samples if requested, just let me know which commands to run.

Steven Boyer