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Discussion Starter · #1 ·
I see that the Silicon Image iScan Ultra has a DVI output, but no DVI input-- what is the point of this, if one has to still hook up a digital device like a DVD player through the analog inputs-- thus ruining an all-digital data stream? Isn't a system only as strong as its weakest link?
 

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I believe it's good to have since the actual scaling occurs in the digital domain so you avoid one digital to analog conversion right before your display gets the signal. It would be nice to have both, but right now you're more likely to have a display that accepts DVI in than a device that outputs DVI.
 

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the Iscan products are basically just deinterlacers, so the only time that they would be used is when you have interlaced 480i content, which only comes in an analog manner. Hence, no dvi in. Advantage is once they deinterlace, no conversion is performed back to analog if you use dvi.
 

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Makes perfect sense.


You want to avoid analog to digital conversions, right (minimizing them is good)?


So, this way, you only have one conversion, just done by the deinterlacer instead of your display.


As DVI doesn't support (not without hacks and tweaks) 480i, it makes no sense to add it as an input to iScan. The only catch is a DVI passthrough, which could have been a nice addition.
 

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I hadn't thought about a DVI pass-through -- that would be nice. I know with my Faroudja NRS I appreciate the DB15 (VGA) pass-through . . . Otherwise, I'd have to buy a video switcher, and I already seem to have too many electronic boxes!!!
 

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Discussion Starter · #6 ·
Ok, I guess my confusion is that I want to use a DVI-out-equipped DVD player and possibly connect it to a Faroudja or other motion-adaptive-type deinterlacer--- but I want to maintain the all-digital signal path. Which means I need something with DVI in.


OR, I suppose I could use a DVD player with a Faroudja-type processor built in AND DVI out (Samsung 931, but I've heard bad things about it here on the board). The problem is that I would still need an external deinterlacer for HDTV, right?
 

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I think you're confusing scaling with deinterlacing. Deinterlacing is usually performed in relation to 480i content, and turns out 480p content. Deinterlacing can be performed in relation to 1080i content, to turn out 1080p content, but I believe that the only device that does is, the Faroudja 5000, costs $20000+. It is believed that most video proc's basically use one frame of the 1080i content (so called bob or weave) and scale based on that (although someone please correct me if I'm wrong).


Scaling takes content and outputs it at the native rate of the display device.


So, generally, it's not that you need an external deinterlacer for HDTV, as much as you need an external scaler -- and you still will need an external scaler for DVD output at 480p, since you need to scale this as well.


You can of course rely on your display device's internal scaler, and output HDTV resolutions and DVD output via DVI into your display device. Or, get a scaler with DVI inputs (most newer ones), and send HDTV resolutions and DVD output via DVI to that, have the external scaler to the scaling, and then send it to your display device.
 

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Quote:
Ok, I guess my confusion is that I want to use a DVI-out-equipped DVD player and possibly connect it to a Faroudja or other motion-adaptive-type deinterlacer--- but I want to maintain the all-digital signal path. Which means I need something with DVI in.
Well, unfortunately, you can't do this, because as Ofer points out, DVI doesn't support the the 480i video format used by the DVD standard. That's why all DVI-capable DVD players must do the deinterlacing themselves before sending the signal out of the DVI output.


An SDI connection, however, does support 480i. Too bad SDI isn't a standard option on common DVD players. But many folks on this forum have DVD players that have been "hacked" to include SDI outputs, so they can feed the pure digital output to an external deinterlacer.


The new DVI "upgrade" known as HDMI adds support for 480i. So when HDMI-enabled DVD players start coming out, you may be able to use an external deinterlacer with one of these. I say "may" because the DVD player designer may choose not to use the 480i capability of HDMI for some reason. For example, HDMI sources are required to detect "old" DVI displays and handle them properly, which among other things requires disabling 480i support. The designer may just decide to forego all that extra detection logic and just output resolutions that are back-compatible.
 

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mdrydja,


incorrect. The HD LEEZA ($4000 list price, I believe) is capable of doing this and has a DVI input (which it does deinterlace even with 1080i) and an SDI input (for 480i deinterlacing for all-digital input).


The Vigatec Dune also has this capability (also costs far less than a Faroudja 5000), but it does not resolve the full 1080i resolution.


As we have seen from Joe Cane's adventures in 1080i, D-Theater doesn't resolve the full 1080i resolution properly either, so I'm not sure if this is critical in the next few years until proper 1080i comes to light (Joe is apparently pushing for a WMV9 version of HD). Not sure how well 1080i via ATSC functions.
 
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