video bandwith

[dale331]

I'm buying a receiver for the future as well as the present. I now have a TV but the next one will be a HDTV so I'm looking at the video bandwith.
Onkyo and HK have 50Mhz,
Yamaha has 60Mhz,
Denon and Pioneer have 100Mhz
which is double the Onkyo-HK brands. How important is this bandwith as far as the future goes? Anyone have a crystal ball?
Thanks Dale

[edtyct]

Theoretically, 35Mhz is required to pass a 1080i signal, but differences of opinion exist. Arcam recommends 100 to 150Mhz, which seems like overprotection against signal loss to me. 1080p looms as the bandwidth hog of the future, but by the time it gets here, receivers unable to pass it may also be audio-challenged, and almost all of the display devices in use now (both sources and sinks) will be video-challenged. One way around the problem for video, if it should ever emerge for you, would be to connect any 1080p source directly into its appropriate display without getting a receiver involved at all (presumably via HDMI, although HDMI, as now constituted isn't fully capable of 1080p either; its predecessor DVI is). Personally, I prefer that strategy even now for HD sources. But to answer your question, all of the receivers on your list are HD-capable so far as today's state of the art, and that of the immediate future, is concerned.

Ed

[kexodusc]

Hi Ed,
Can you explain why DVI is 1080p but HDMI isn't? What would it take to bring HDMI up to snuff (if that's even possible? I guess I've been wrongfully under the impression from my readings that HDMI was simply DVI plus audio, nothing less.

[edtyct]

Hi Kexo,

The short version is that HDMI is DVI with sound, since in most cases they can work well together, but HDMI is slightly more versatile in the video formats that it can read. DVI can't quite hide its computer-technology RGB roots. I don't think that HDMI can't handle 1080p at 60fps unless it is dual-link (DVI can), and dual-link HDMI is pretty much nonexistent at this point.

Ed

[kexodusc]

Ahh..sounds like it's more technical than I thought.
I'm not familiar with "dual-link", but is this aspect of DVI (and potentially HDMI) required to be present in the cable or in the equipment terminals for it to work? Or both?
Like many, I was under the impression that HDMI and DVI were essentially the same, but that's just oversimplifying I guess.
May I ask, then would a DVI-to-HDMI adaptor permit 1080p or is it more complicated than that?
Not that I expect 1080p to be mainstream in the next 5 years or so, just curious.

[edtyct]

Kexo,

Sorry. One of the rare occasions these days when I could escape a computer. The digital video standards aren't that forbidding in real-world use, but if you read the specs for DVI and HDMI, they get really technical. First of all, the difference in what the two protocols support is relatively minor. DVI supports RGB 4:4:4, and YCbCr 4:4:4, and so does HDMI. But HDMI adds YCbCr 4:2:2. An upconverted signal from an HDMI source to a DVI target (via an adaptor) can be problematical if the HDMI source sends the wrong color space to the DVI sink---incorrect HD color rather than SD color, which is what upconverted 480 requires. No DVI component on the market can make the correction, whereas HDMI components sent the wrong color often have a manual adjustment. No big deal, but they are differences.

If a component has a dual-link connector on it, dual-link cables are required for full bandwidth. Theoretically, dual-link cables can be used in installations that have only single links, though they offer no advantage. A DVI to HDMI dual-link adaptor won't permit 1080p unless the HDMI component itself, whether on the front or back end, is a dual-link product. But we aren't anywhere near implementing something like that, and I can imagine a host of problems when we are.

Ed

[AVMASTER]

Edtyct,
in light of the potential problem with 1080p passed on HDMI, would it be safe to say that a receiver with DVI inputs and output be a more futureproof purchase???

[edtyct]

That's a good question. DVI might be more future-proof in some possible world, but I'm not sure that we're living in it. We might be. But HDMI is rapidly supplanting DVI as the connector of choice. By the time 1080p becomes the norm in displays and souces (and something else has begun to pop its head over the horizon), DVI will most certainly have become a thing of the past, and HDMI will have long since made the necessary adjustment. At that point, HDMI audio conduits will exist on all displays, and all receivers will have HDMI video inputs. Many standard DVD players with digital outputs even now have gone exclusively with HDMI. Few of the hi def DVD makers will return to DVI later, when displays with true 1080p inputs exist in earnest. Nor will the makers of these true 1080p displays have any incentive to include DVI inputs when no DVI player currently available can pass 1080p. If the players have to start from scratch, why go back to an outdated protocol? In the 1080p era, those people still using standard or upconverting DVD players capable of only 480p or upconverted 720p/1080i via DVI will still be alive and kicking only by grace of an adaptor and backward compatibility, and those people still using displays at 720p or 1080i only by grace of downconversion. What's that proverb about change as the only thing that stays the same?

Ed