[vlc-devel] IVTC and 4:2:0 chroma, again...

Juha Jeronen juha.jeronen at jyu.fi
Thu Apr 7 18:03:25 CEST 2011

Hi all,

Some more IVTC testing...

It seems the AltLine strategy is not the only one for telecining 4:2:0
chroma, but only the most common.

Usually this strategy removes the telecine correctly, but the second
half of Dirty Pair (the 1985 TV version, recently released on R1 DVD)
gets incorrect chroma in one output frame out of four - i.e. the frame
that has to be extracted from the telecine. In these frames, every other
chroma line comes from the next frame. This suggests that the correct
chroma lines are all located in the same frame, specifically probably
the one that comes earlier in the stream.

Curiously, the first half of the same series (it was released in two
sets) works correctly with AltLine, so it seems that someone
reconfigured their telecine equipment midway through :)

As for the filter, I think autodetecting this is right out, at least at
the moment. I suppose the chroma mode could be made configurable, like
it is for Phosphor.


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