Path: utzoo!attcan!utgpu!watmath!att!dptg!rutgers!apple!vsi1!ubvax!ardent!sim!sleat From: sleat@sim.ardent.com (Michael Sleator) Newsgroups: comp.graphics Subject: Re: Frame rate (was: Re: HDTV and ATV Glossary (TN32)) Summary: What? Me tedious? Message-ID: <8034@ardent.UUCP> Date: 31 Aug 89 01:38:27 GMT References: <13130@well.UUCP> <17400008@hpfcdj.HP.COM> <470@telesoft.telesoft.com> Sender: news@ardent.UUCP Reply-To: sleat@sim.ardent.com (Michael Sleator) Organization: Ardent Computer Corp., Sunnyvale, CA Lines: 61 In article <470@telesoft.telesoft.com> dar@telesoft.telesoft.com (David Reisner) writes: >In article <17400008@hpfcdj.HP.COM>, myers@hpfcdj.HP.COM (Bob Myers) writes: >> ... there's a distinct difference between a >> "60Hz non-interlaced" display, and a "60Hz interlaced" display. In one >> case, we're talking frame rate; in the other, the "60Hz" is, of course, the >> *field* rate. ... > >I agree with the above. The discussion about interlaced and non-interlaced >systems with the same frame rate may be true, but is largely irrelevent. What is it that you agree with? That the meanings of "60Hz non-interlaced" and "60Hz interlaced" are, "of course," universally and unambiguously understood? I hope not, because I think that's far from true. (The predecessor to the quoted posting clearly demonstrates this.) Far better to say what you mean. Irrelevant to whom? There are certainly issues here which are relevant to those who design, specify, or evaluate video monitors or the hardware which drives them; a class of people with a significant representation in this newsgroup. By extension, these issues are relevant to those who use such systems. To say, in effect, "non-interlaced displays run at 60 frames/sec and interlaced displays run at 30 frames/sec and that's the way the world is, why talk about it" may indeed reflect the preponderance of current practice, but it does nothing to further the state of the art. Rather, mindsets like this inhibit advancement of the state of the art. This was the point of my "interlace as a dirty word" diatribe a few days ago. The designer who thinks that interlacing is a guaranteed cheap way to cut his bandwidth requirements in half is no better than the customer who thinks "Interlace? Ick. I'm not going to touch it." Neither one is critically appraising the real issues. >A common interlaced computer monitor would have a 60Hz field rate and a 30Hz >frame "rate". A common non-interlaced monitor would have a 60Hz field and >frame rate (since they are the same). Given these numbers, the non-interlaced >monitor will demonstrate less flicker and other objectionable artifacts in >almost all cases. > >If someone disagrees significantly with my "common frame rate" estimates, >I am of course interested in hearing about it, but please include specific >information about some specific display systems (e.g. VGA). If you happen to have an Ardent Titan with a stereo display, you may notice that in certain modes it runs at 120 fields/sec 2:1 interlaced. Common? No. Relevant? To some of us. (By the way, the Sony GDM-1950 monitor does a very nice job with interlaced video. I hope the replacement for it does as well. (You guys down there in San Diego listening??? :-) )) Michael Sleator Ardent Computer ("Stardent"? Well, it's better than "Arellar"!) 880 W. Maude Sunnyvale, CA 94086 408-732-0400 ...!{decwrl | hplabs | ubvax | uunet}!ardent!sleat P.S.: I'll be gone for a couple of weeks and follow-ups will probably have been purged by the time I get back, so if you want to flame me, you should probably mail me a copy. Actually, that goes for low-temperature replies also.