Re: Apple II NTSC emulation

[Alex Freed <alex_news@mirrow.com>]

vladitx wrote:
> I started this quite some time ago and then buried it, but recently
> got to it again and today there are first results:
>
> http://softjunk.org/sw/apple2/ra2/files/screenshot/ntsc/
>
> The decoding is done via lookup tables (depth of 2**13 used for the
> test images), as was agreed back then with M.J. Mahon. The lookup
> tables are generated through I/Q demodulation with asymmetric filters.
> Full line NTSC decoding will look bit different (and probably better),
> but it's the table approach that is important now.
>
> So, how does it look like? I don't have access to color Apple monitor,
> so can't really judge how far it may be. :-) Both in terms of colors
> and resolution.
>
> Tint is adjustable, and I guess the Apple II has a noticeable phase
> offset due to gate delays, but the images were generated with
> "idealistic" zero offset.

Very interesting! If you care to publish the algorithm, we can probably
do it in hardware using the CB using BRAM for a look-up table. Right now
my colors are very basic and calculated from just 3 pixels and the high
bit.

-Alex.