[FFmpeg-user] FFMpeg problem using fieldmatch and decimate filters to IVTC

[Nicholas Robbins]

> On Tuesday, May 6, 2014 2:47 PM, Steve Boyer <steveboyer85 at gmail.com> wrote:

> > Nicholas,
> 
> Thanks for looking at the sample files. I knew that the source material
> switched back and forth between interlaced video, FILM, and funky
> combinations of the two throughout each episode as you outlined. It didn't
> click that the correct source frame rate would vary in these scenes - which
> is starting to make sense that if a portion is made to be played at ~30
> FPS, has a frame removed and shift the video stream, and played at ~24 FPS,
> it would introduce the AV desync and quickly become noticeable. It simply
> didn't occur to me! Sounds like either pullup, fieldmatch+yadif, or even
> just yadif the whole thing without a framerate conversion would give me a
> good encode without any AV desync.
> 
> I use MoboPlayer on Android and am going to try out another player soon. I
> don't think they do VFR, but since the shows are authored to NTSC DVD
> standards to a CFR of ~30 FPS (telecined ~24 fps and NTSC interlaced), it
> shouldn't be a problem.


Yeah, if you care enough, working out what combination the producers would be the first step to work out what filters to use. If you want to just throw something at it, you could try:

-vf pullup,dejudder,idet,yadif=mode=1:deint=interlaced,fps=60000/1001

remove the fps if your player can play VFR video. Otherwise change that number to the highest CFR your player can play. It doesn't change the file size that much.

> I noticed the ffprobe seemed to look quite strange as well. Mplayer and
> other players think that the vob files are something stupid-short like a
> minute as well. I ripped the files from the DVDs using dvdbackup and then
> ran "cat *.VOB > 4.18.vob" to join the two together. If you have a
> suggestion on a better method, I'm all ears.

I've spent time doing the exact same thing (well for my STB not my phone.) I've got what I have working up at https://github.com/Nicias/dvd_scripts

First I run either dvd-rip.sh (which uses makemkv) or piecewise-rip which uses a combination of mplayer, ffmpeg, mkvmerge, etal. This produces a bunch of mkv's in a holding folder. I then run report.sh on them. All of this happens automatically actually upon dvd insertion.

Then I look at the fps's reported by report.sh and visual inspection (the visual inspection is very brief if it is a series I am familiar with.) to determine what mix of fps, telecine, interlaced, etc. this file is. Then I use relink rename the files appropriately to indicate what treatement they should get, so something like   

Babylon.5.1993.S01E20.b5.mkv
Hero.2002.film.nostrip.mkv
Oceans.11.1960.film.mkv

When I have a bunch built up, usually a whole season or two, then I run transcode.sh on the batch of them. 

Feel free to use those scipts, but no guarantee they will work or won't burn down your house, blah blah blah.


> Thanks for taking the time to put me back in my place!

No problem, just paying it forward.


Nicholas