Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!mcnc!taco!hobbes!kdarling From: kdarling@hobbes.ncsu.edu (Kevin Darling) Newsgroups: comp.sys.amiga.hardware Subject: Re: DCTV + CDTV = A SMASH HIT! Message-ID: <1991Apr7.003336.3219@ncsu.edu> Date: 7 Apr 91 00:33:36 GMT References: <10000026@hpmwmat.HP.COM> Sender: news@ncsu.edu (USENET News System) Organization: North Carolina State University Lines: 36 mikep@hpmwtd.HP.COM (Mike Powell) writes: > As CDTV is pointed primarily as a NTSC device, DCTV would be right > at home in the CDTV, and would give it an AMAZING jump on the > competetion... HAM is ok. but 16 million NTSC colors is FANTASTIC! A good idea, but I'm afraid that it would hardly "give it an amazing jump" on CD-I, which is CDTV's competition. In fact, not even close. CD-I has two main image planes, each with a full video chip and 512K RAM. Either one _alone_ has modes superior to Amiga gfx... but they can also be swapped in priority, each can be of almost any mode (see below), and the planes can be color-keyed, dissolved, or overlaid, all in hardware. Of course, modes can be changed on a line/line basis, just as in the Amiga. The main modes have 4/7/8 bits/pixel from a choice of 4 or 16 million colors. In other words, 256-colors in a 360x480 screen mode, with a 3/7-bit screen also available for overlays. There are also 3/7 bit color RLE modes: the data consists of color RLE lines (perfect for cartoons), which the chip decodes/displays _on the fly_ instead of having to have the cpu unpack the data in memory first. Then there is the Delta-YUV (DYUV) mode, which is superior to HAM [ I've been told the Amiga was originally supposed to have DYUV ] because it allows luminance changes on a per-pixel basis while the color changes slower. As the eye is more sensitive to luminance, the pic looks better. Finally, both planes may be combined to form a 15-bits/pixel direct RGB mode. Each plane can also be fitted with its own blitter. CPU->video RAM accesses are always interleaved half and half... meaning gfx updates are faster than the equivalent Amiga modes. The cpu is also around 50% faster than CDTV's. To be blunt, CD-I gfx is what the basic Amiga gfx should've been by now. Perhaps CBM should use CD-I chips. best - kevin