[FFmpeg-user] Interlaced x264

[Andy Furniss]

Anatol wrote:
> Andy,
> U don't see 'weightp' warning, because I have 'weightp=0' at the end of the
> 'x264opts' list in my "monster" command line (its sometimes a fun to be a
> monster ...).

Oh OK

> The results with ffmpeg3 are the same (for monster and simple cmd-lines).
> In all cases the x264 gets the correct interlaced params - media info shows
> "interlaced=tff" in the 'Encoding settings', but the 'idet' test remains
> the same.
>
> But, it look like 'tinterlace' produces something more meaningful -
>
> [Parsed_idet_0 @ 0x1fdb060] Repeated Fields: Neither:   118 Top:     0
> Bottom:     2
> [Parsed_idet_0 @ 0x1fdb060] Single frame detection: TFF:   105 BFF:     2
> Progressive:     1 Undetermined:    12
> [Parsed_idet_0 @ 0x1fdb060] Multi frame detection: TFF:   120 BFF:     0
> Progressive:     0 Undetermined:     0
>
> But only with 'simple' cmd line:
>
> ffmpeg -threads 1 -i BBB_30sec.mp4 -c:v libx264 -vf
> "tinterlace,fieldorder=tff" -flags +ilme+ildct -threads 4  -y
> BBB_30sec_interlaced.ts

You need to use tinterlace properly to make interlaced.

https://www.ffmpeg.org/ffmpeg-filters.html#tinterlace

I don't know why you need fieldorder.

https://www.ffmpeg.org/ffmpeg-filters.html#fieldorder


> Do u know whether there are any quality or other issues with 'tinterlace'
> filter?

Carl Eugen is correct - you are basically breaking videos doing this.

Why do you need to make interlaced from progressive?

If you have good reason (and 50/60 fps source) then you also have to
be careful around chroma conversions and any scaling filters for which
may get auto inserted and break chroma (cause it to bleed between fields).

Having never done this myself I can't just give a working command line.