[theora-dev] Analogue artifact estimation

[Daniel B. Miller]

hi --

Interesting points you bring up.  Realistically, theora is going to be
focused more on the definition of the bitstream and issues of
audio/video integration into the OGG format.  Advanced thoughts about
new codec ideas might be well received at the tarkin list
http://www.xiph.org/ogg/vmail.html.

Not to discourage you from thinking about these things as they relate to
VP3;  however it's important to note that our primary objective
will be to define the bitstream before tackling major improvements in the
encoder.

 ___  Dan Miller
(++,) CTO and founder, On2 Technologies

On Wed, 28 Aug 2002 jbradford at dial.pipex.com wrote:

> Hi List,
>
> Just batting a few ideas around here, but would it be possible to
> include in to the codec, estimation for common video artifacts that
> occur in the analogue world?
>
> For example, anything that's gone through a composite stage will
> likely have dot-crawl and false colour - if we can recognise this
> effect in the encoder, we can treat it as a special case.
>
> Other artifacts that come to mind are:
>
> * 3-2 Pull down
>
> * 30/25 and 25/30 FPS conversion artifacts
>
> * Dropouts, (both noisy, a-la VHS, and solid bars, a-la BetaSP, (which
> I believe halves the chroma resolution - can we possibly take this in
> to account as well?) )
>
> * Stobe effect of a CRT filmed by a different scan-rate camera
>
> * Colour changes in multi-layered painted cel animation, (where a
> character is, say, talking, and they repeatedly add and remove a cel
> from the top layer, their face flashes bright and dark :-) )
>
> Infact, existing video compression codecs do a *terrible* job of
> encoding hand painted animation, especially anime, despite claims by
> well known studios that it is not an issue.  Good motion estimation to
> compensate for poor registration of animation would be worth
> investigating.
>
> I think that the problem with all codecs to date is that they are
> designed to compress perfect material originating directly from a
> camera.  In my opinion, the above *analogue* artifacts are what give
> the digital codecs a hard time.
>
> I'd be very interested on any comments on these points.
>
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