Originally posted by: jiffylube1024
Larry, I see where you're going with this argument, but I'm not talking about subjective tests here here - I'm talking about how the technologies work objectively.
I'm quite aware of how the technologies work, objectively.
Both have signal-degradation issues, objectively speaking. Whether or not those are perceptable to the user, is a subjective question, and we could both argue that until all of the oxygen on earth was used up, I'm sure.
Originally posted by: jiffylube1024
LCD monitors require more digital to analog conversions to run on a VGA connection. Whether the user perceives a difference or not is irrelevant for my argument - when you run an LCD monitor by a VGA cable, the signal needs to be translated to an analog signal for the cable run, then gets reconverted into digital by the monitor's circuitry.
Yes, it results in some level of signal degradation. It is more pronounced when running at higher resolutions/refresh-rates, is it not?
I'm not entirely certain about the need for additional A-to-D and then again D-to-A stages in all cases though. The LCD panel itself, physically, is still analog, not digital. I'm actually wondering, if on lower-end panels, they haven't implemented a way to drive those panels directly using the analog signal, and thus cutting out a bit of additional cost as well as additional signal-processing steps.
Originally posted by: jiffylube1024
With a DVI-VGA adaptor from a DVI-I port, all you are doing is adding another 1.5" or so of cable between the video card and the monitor. This is nothing like adding a digital-analog-digital conversion.
No, but again, "objectively speaking", it still results in some level of signal degradation. It changes the transmission-line characteristics, reducing the overall effective analog bandwidth, which will only become noticable if one tries to use that level of bandwidth, which only happens when running at higher resolutions/refresh-rates.
Originally posted by: jiffylube1024
Like I said before, if the DVI-VGA adaptor is reducing quality of the image on the CRT monitor, then it's either poor shielding/wiring on the video card or in the adaptor, but it's a problem that's fixable based on the technology. Done correctly (ie not with cheap filters/cables), it should be no different from a straight VGA connector.
The same exact argument could be said, for driving an LCD panel based on an analog input signal. If it results in noticably increased image degradation when using a VGA analog input to the panel, then obviously your problem is that you are simply using a low-quality panel, and should use a better-quality one.
Originally posted by: jiffylube1024
LCD on VGA, however, is sub optimal no matter how you look at it. It is an unnecessary conversion step to the digital image.
Again, the LCD panel
itself is still physically analog. We don't live in "The Matrix" yet.
Originally posted by: jiffylube1024
Then we'll have to agree to disagree on this point then, because adding 1.5" to the run to a VGA monitor and converting a digital signal to analog then again to digital is comparing a molehill and a mountain.
The simple point, which was apparently overlooked, is that they
both degrade the image quality of the signal.
The corresponding point was that why should
I make a sacrifice in terms of
my display's signal/image-quality, for someone else's display needs? Therefore, the best solution would be to have two different lines of video-cards. The fact that: 1) having a dual-lineup of video cards isn't currently the norm, and 2) the current norm of one DVI-I and one VGA port being the current most cost-efficient solution in the market, and 3) the fact that dual DVI-I outputs would cost more, all seem to have been overlooked by Jack.
Any claims that DVI-to-VGA adaptors do not degrade the signal at all, whilst at the same time claiming that forcing LCD users to use the analog VGA input on their panel would degrade the signal far too much, is both blatantly objectively false, and subjectively dismissive and hypocritical.
Originally posted by: jiffylube1024
Would you want to watch a DVD player through composite video if you had Svideo or component video plugs on your TV?
While this isn't a directly analogous situation (for starters, all three of those interfaces are analog), it's similar. Why degrade your image quality through an inferior connection when putting the better connection type costs virtually nothing more and (contrary to your claims) doesn't affect signal quality of the old type of connection.
I'm not sure what you mean by "contrary to my claims", because I made no claims about composite/S-video/Component-video signal quality in this thread, that I am aware of. And adding those additional analog input types does not cost "virtually nothing" more, otherwise we would have been seeing televisions, even the cheapo Made in China ones sold at Wal-Mart, with included S-Video inputs for a long time now. But yet, even today, that seems to be a rarity, until you move up to the "home theater" quality TV sets.
I guess what I am saying is, if what you are claiming about nearly-zero incremental cost is true, then why aren't
all of the lower-end LCD displays, all sporting DVI inputs? (And then, by extension, even the lower-end video cards would also have the necessary DVI outputs to drive them included by default as well.) But they aren't, are they? I wonder why... (hint - the answer is "cost").
I guess the point is, subjectively speaking, NO, I wouldn't want to watch anything via a means that would result in a degraded signal, if I had a better-quality means of obtaining the signal available. So in that case, the ideal solution would be two seperate sets of cards, one with DVI/VGA, and another with DVI/DVI.
(Or my suggested solution, to run two DVI-D TMDS signals out via one DVI physical connector, and then split them via a dongle. Since the signal is still digital at that point, it shouldn't result in the same sorts of degradation that the analog DVI-I to VGA adaptor causes, because the digital logic recievers should still be able to discern the proper thresholds for the digital signal levels, and reject minor analog noise overlaid on that signal.)
Originally posted by: jiffylube1024
That's just the way dual-link works. The two TMDS transmitters are tied together to drive a single display at higher bandwidth. If I'm wrong on this please provide me with a link to some technical documentation because the last I checked, dual link DVI could drive only a single display (at any resolution, even low bandwidth ones).
That's changing the way the interface works - if it could be done cheaply it would make sense but I'm pretty sure they set up dual link DVI the way it is for a reason (simplicity/cost).
But I'm saying that there is nothing inherent in either the signalling specs, or the physical connector, to require that, that I am aware of - only that the current implementation of it is likely done that way for cost reasons.
I will research that some more, I'm a bit curious myself. Indeed, it would be a relatively nice feature of modern video cards if this is possible - they could run dual TMDS links to one DVI connector, and then split them off, and drive one LCD/DVI display, and then use the other for driving an HDMI display - basically to get a TV-out for more advanced HDTVs, without having to add another physical DVI port on the backplate. That could be a win in the future, and of course also useful for dual DVI LCD setups too.