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

[Steve Boyer]

On Wed, May 7, 2014 at 6:37 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
>
>> -vf crop=704:480:10:0 -vf fieldmatch,decimate
>
> I always wonder if this is supposed to work (it
> apparently works, but I don't think you can protest
> if it breaks in the future), please only use one
> video filter chain per output file.

Just to shed some light, it indeed works.

> Just in case the following is not clear: ...

Right, fieldmatch is the actual reconstructing the progressive frames
(PPPII --> PPPPP), but leaves a total of 4 unique frames and a
duplicate frame for every 5 frames (by default). It in turn must be
used with -vf decimate or -vf fps or -r or some other filter to remove
the duplicate frame to achieve the 23.976 frame rate.

>> -vf pullup,fps=24000/1001
>
> This unfortunately does not work;-(
> (This is documented iirc.)

I've seen "-r is depreciated, use -vf fps=24000/1001," "-r works
fine," as well as "use -vf fps=fps=24000/1001." In my experience with
other encodes, -r seems to work best as well. I did have some problems
with this particular series where it would get all herky-jerky,
because ffmpeg was dropping a unique frame due to the editing method
of the series. (see below)

>> -vf pullup -r 24000/1001
>
> As said, this works fine here for the sample you
> uploaded.

I really should have provided a larger sample -- I can do that tonight
if you would like me to tonight (I'm at work and that box is powered
off ATM). Looking back at the sample.vob, it is entirely telecined.
With this particular series, they recorded on film and did editing and
special effects in NTSC, which lead to some weird frame-rate mixing.
This particular sample didn't include any of the funny mixing of the
two.

I encoded last night using:

-vf fieldmatch,yadif=deint=interlaced

and left the resulting video playing at the original framerate of
30000/1001. It stays in sync throughout the entire episode, and it
looked like all frames were all de-interlaced.

> Carl Eugen

Steve