[FFmpeg-user] Confusion about fieldmatch, decimate and framerate (now with yadif)

[Nicholas Robbins]

Ok, on my current sample. I checked the length and framecount using ffmpeg, getting: Frames: 169698 Duration: 1:34:19.29 for a frame rate of 29.97.

However, it reports to be 59.94. So I do 

 ffmpeg -i in.mkv -vf libx264 -crf 17 -preset veryfast -vf "fps=30000/10001,fieldmatch,decimate" out.mkv

In the encode, I get this quite a bit:  "Frame #328307 at 10954.5 is still interlaced" So I think, I should add in yadif=deint=interlaced as per http://ffmpeg.org/ffmpeg-filters.html#Examples-37 between the fieldmatch and the decimate. Like this:


 ffmpeg -i in.mkv -vf libx264 -crf 17 -preset veryfast -vf "fps=30000/10001,fieldmatch,yadif=deint=interlaced,decimate" out-2.mkv

However, the resulting file is visually the same. So I check with 

ffprobe -show_frames -select_streams v  out.mkv | grep interlaced_frame=1

and I get nothing. So all the frames are marked as non-interlaced. I guess fieldmatch doesn't mark the frames it can't deal with. It just leaves them where they are. Do I have any way to detect these frames and deinterlace them?