[Coco] CoCo3 Video Player Version 2 Demo

[John W. Linville]

On Fri, Apr 15, 2011 at 04:23:32PM -0500, Roger Taylor wrote:
> At 12:54 PM 4/15/2011, you wrote:
> >This is a demonstration of version 2 of my digital video player for
> >the Tandy Color Computer 3. Version 1 just never performed as well as

> YES!!
> 
> Btw, have you tried Floyd-Steinberg or Burkes dithering in 16 colors
> to see what will happen?  I assume you are preencoding the dumped
> pages.
> 
> Nice!

I hadn't previously heard of Burke's, but I have tried Floyd-Steinberg
and it seems that they are both in the "error diffusion" category
of dithering.  FWIW, I also tried Riermersma which is more-or-less
in the same category.

This category of dithering does produce some very nice results with
_single_ frames.  The thing is that with this type of algorithm, a
change in even a single pixel in the input tends to produce lots of
changed pixels in the output.  This has two undesirable side effects:
lots of extra "changes" eating-up the video bandwidth; and, a "sparkly"
effect in the video playback (i.e. everyone in the video looks like
they are being swarmed by bees).

You can see the "swarming bees" effect even in this clip I did with
the version 1 of my player last year:

	http://www.youtube.com/watch?v=DIK7xm3tAqU

In the "ordered" category of dithering, only the individual input pixel
determines the color of the output pixel.  So, when a given input pixel
changes only it's corresponding output pixel is effected.  This means
that only actual changes in the input create demands on the output
bandwidth, and the output images are stable with no "sparkly" effect.

It is unfortunate that some people seem to really be bothered by the
"structured" appearence of the ordered dithering.  But all-in-all,
I think that "structure" is preferable to "attack of the bees"... :-)

John
-- 
John W. Linville                Someday the world will need a hero, and you
linville at tuxdriver.com                  might be all we have.  Be ready.