[MPlayer-dev-eng] New inverse-telecine filter
vektor at dumbterm.net
Fri Dec 5 00:20:41 CET 2003
Billy Biggs (vektor at dumbterm.net):
> I also won't believe you if you say that doing the progressive
> downscale on progressive content will be _higher_ quality. Keeping
> chroma from only one field seems like a bad, bad idea, given how NTSC
> encoding works. I bet that if you did a proper upsample converting each
> field to 4:2:2, then merged them, then downscaled using a good filter
> back to 4:2:0, you would get a higher quality image.
I think I can make this argument even stronger. Say I have a 4:2:2
frame and it IS progressive. Is it correct for me to DROP every second
scanline of chroma to get a 4:2:0 frame? No, it is not. I should
downsample using a higher order filter, even better, one that's actually
to spec for MPEG2's 4:2:0 format. Otherwise, I get aliasing.
So clearly, just looking at chroma from _one_ field and calling that
the chroma plane of a 4:2:0 image is never correct.
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