[FFmpeg-user] How to deinterlace strange interlacing

[Ulf Zibis]

Hi Christoph,

Am 03.04.21 um 00:42 schrieb Christoph Gerstbauer:
> Hello, forget my last mail. The original video is destroyed in the first place.
>
> If you SPLIT the fields from the original MPG you see PER FIELD interlacing artefacts. That is a sign that the original video from tape was not correctly DEINTERLACED (25i-> 50p -> 25p) when going into MPG format.
> You see in the picture TOP field and Bottom field of the MPG file.
> Normally NO interlacing lines should be in one FIELD.
I was thinking about an algorithm, which could work as follows:

1. Extract all 2nd lines from a frame
2. Rebuild planes
3. Intelligently filter or move the stripes horizontally
4. Merge the planes or create a stream with double frame rate to create a visually better video.
I was in hope, that such algorithm exists somewhere

> See attached file.
>
> So I guess the way of the signal was:
>
> 1. ) TAPE (I guess betacam or imx): Interlaced top field first (25i)
> 2.) digitized into file as PROGRESSIVE 25fps without handling the interlacing. (25p)
> 3.) ENCODING to MPG with a bottomfield first flag, but already destroyed fields.... (25"i"/p)
Seems probable.
> This can not be repaired.

Thanks for your thoughts,

-Ulf