[MEncoder-users] Trying to fully understand de-interlacing.

[Andy Furniss]

Peter wrote:

> Only one person downloaded the files so far, I'd be interested to know
> if this person thought it was a good test for deinterlacing, because I
> 'designed' it to be that.

It seems OK, but then I don't know what I am talking about :-)

One suggestion from my experiments ripping PAL SD camcorder tapes 
(though I was actually keeping interlacing) is -

Have two saturated colours side by side on a horizontally moving object, 
that way you can tell if the 4:2:0 colour space is being correctly 
treated as interlaced, if for example you had other filters before the 
de-interlace.

As I said, when I did it I wanted to keep the interlacing so I examined 
weaved frames (You can't use xv for this as it only does progressive, 
use -vo x11).

IIRC yadif will assume interlaced chroma - but I found when testing 
4:2:2 (though pointless for PAL) that it only accepted 4:2:0, in which 
cads it became important to specify  -vf scale=-1:-1:1 (for the s/w 
4:2:2 to 4:2:0) to avoid sharp vertical edges between saturated colours 
being blurred after deinterlacing.

I admit that's a bit of an artificial case, but when working with 
interlaced material, it's always worth remembering to "tell" 
filters/codecs as 4:2:0 colour needs to be handles per field rather than 
per frame.