Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!rutgers!gatech!taco!hobbes.catt.ncsu.edu!kdarling From: kdarling@hobbes.catt.ncsu.edu (Kevin Darling) Newsgroups: comp.sys.amiga.advocacy Subject: Re: CDTV, CD-I, DCTV, etc Message-ID: <1991Apr20.131149.28247@ncsu.edu> Date: 20 Apr 91 13:11:49 GMT References: <1991Apr16.071344.20589@ncsu.edu> <1991Apr16.154153.11706@mintaka.lcs.mit.edu> Sender: news@ncsu.edu (USENET News System) Organization: North Carolina State University Lines: 75 [ Sorry for reply delay. In the interest of reader sanity, I'll answer his message in two articles. First, video modes: Later, tech details. ] In <1991Apr16.154153.11706@mintaka.lcs.mit.edu> rjc@geech.gnu.ai.mit.edu (Ray Cromwell) writes: > Why bring RLE up if it can only be used for line art animation? What would > you rather have, 1/4 screen 15fps HAM or [invalid] or full screen cartoons? An incorrect comparison. RLE is just _one_ of the modes (do I have to repeat this ad infinitum?). Obviously it has great advantages in certain cases, especially since it can be overlaid on top of a screen of any other mode. A more comparable choice would be 1/4 screen HAM against either 1/4 screen CDI DYUV, or even against CD-I 256-color mode for that matter. > What I want to know is, what is CD-I's playback rate for FULL COLOR > FULL SCREEN digitized data? Whatever it is, it'll be faster under CD-I for the resolutions you keep talking about. See coming article for why. >>Want to ripple the flag a bit? CDTV = intense cpu/blitter action, or costly >>multiple screens already in memory. CD-I = flip display pointer to another >>_tiny_ section of RLE memory data... under copper control alone if wished. >>The memory and cpu savings can be almost beyond calculation. > > Yes, but the images must be _canned_ ahead of time on the disk. What about >providing a nice windowed/gadget interface with animated video interacting >to the user. Canned video is nice, but what a video paint program, or a >multimedia authoring disc? Even a 14mhz 68000 can't handle the blitter's >speed. One of the advantages of CDROM _is_ that many images can be on disc. It's expected that both systems will try to take advantage of this when able to. Given the RLE example, the cpu can easily be handling user interface details _while_ the animated data comes off disc, with minimal cpu time wasted on the animation. With the CD-I dual video playfields, this is in fact should be incredibly easier to accomplish. But no, obviously you wouldn't use RLE in a video paint program (altho I can think of ways to do it... not much worse than doing the same in CDTV HAM). You'd use the 16 or 128 or 256 color modes instead, don't you agree? Those blitter assumptions will be handled in a later article. > I don't understand how CD-I gets full screen full motion full color > photographic quality video with just RLE compression and 170k/s xfer rate. > Not all data can be compressed. With C-Cube's JPEG compression chip and > a fairly fast HD you can do real time animation from a harddrive with > 25:1 compression. Why didn't CD-I use this. JPEG is meant for stills (altho some Apple/IBM types use it temporarily for motion). MPEG is the one you meant, and is what will be used by players later (both players, we would assume). BTW, neither CDTV nor CD-I are claiming fullscreen/motion video yet. (Where _do_ you get your information? Certainly not from any of my messages.) Sure, Philips had intended to include it in the first CD-I consumer players, but the MPEG standard wasn't finished until just this year (video in September, audio in December), and quantity chip output will take a while to come. > The CD-I consortium should have invested in improving CDROM > technology and making it cheap, instead of trying to kludge I-TV on > top of such a low bandwidth device. Uhh, why do you think both players will be so affordable? That's right: cheap and proven CDROM technology. In addition, it was expected that MPEG would've been finished far sooner than it was. Not their fault. I do agree with you that it would be nice to see faster CDROM drives/etc. Ummmm. So then why did CBM bring out CDTV so prematurely? PS: I'll ask a favor now, if you can take a deep breath and grant it ... stay away from blitter topics until I can finish and post an article on that subject. I think that's fair. thanks! - kevin