[MPlayer-dev-eng] New inverse-telecine filter

Billy Biggs vektor at dumbterm.net
Thu Dec 4 22:26:16 CET 2003

Zoltan Hidvegi (mplayer at hzoli.2y.net):

> > > But what I'm saying is that if it did give interlaced chroma, than
> > > it would destroy the chroma of progressive frames, so encoding
> > > movies from TV would look bad.  There is no correct way to
> > > subsample mixed interlaced/progressive 4:2:2 into 4:2:0 without
> > > knowing what is interlaced and what is progressive.
> > 
> > I'm glad you phrased it this way because I think this is the subtext
> > I was reading in your emails, and this is what I disagree with.  How
> > does giving interlaced chroma all the time destroy the chroma of
> > progressive frames?  The process of converting from interlaced 4:2:0
> > to progressive 4:2:0 once you have determined that two consecutive
> > fields are from the same progressive frame should be a reasonably
> > straightforward filter.  I understand that you cannot just merge
> > them like you can with the luma, but it should not be very difficult
> > to do something intelligent.
> You are right, once you have 4:2:0, but to get 4:2:0 from 4:2:2, you
> have to scale the chroma, and scaling interlaced content is not the
> same as scaling progressive content.  Just try -vf scale on interlaced
> content, it'll be a mess, because -vf scale is designed for
> progressive scaling.  But the reverse is too, if you had an interlaced
> scaler, like il=d:d,scale,il=i:i (which is not really correct, since
> it would slightly shift the chroma), it will mess up your progressive
> frames, it'll probably add some interlace artifacts to the
> non-interlaced frames.

  Are you asking how to convert 4:2:2 to 4:2:0 ?  There are
specifications for this depending on what 4:2:0 standard you are going
to.  The MPEG2 spec has some details on the filter to use.

  Regarding interlaced vs progressive, given interlaced 4:2:2 content,
it is well defined how to get interlaced 4:2:0 from that.  Similarly for
progressive -> progressive, I am not sure what you rpoint is here.

  Maybe I am not so glad you phrased it like you did above since maybe
now we are talking about different things :)


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