Originally Posted by eggyacid
Okay... here it goes.
I had my Home Theater setup about 5 years ago and at the time, my main receiver does not have HDMI.
I had them ran a HDMI to DVI cable (50 feet) from the ceiling to the receiver. My projector is only 720P and was told HDMI, DVI & Componet should be same quality.
Fast forward, I had recently changed my receiver now with HDMI. I've been using an adapter changes from DVI back to HDMI to my receiver. I know it's probably not the best thing to do, but I don't have much choice unless I re-run HDMI cable.
here is the question... if i don't change my projector (stay with 720P), will I get better quality if I spend the money and re-run HDMI all the way?
how about component?
will I see any quality differences between HDMI->DVI->HDMI vs Component vs HDMI only.
I know if I ever upgrade my projector to 1080P, I would have to upgrade the cable to HDMI only. I'm just trying to use my current equipment until it stops working.
HDMI and DVI share (at least with the early specs) a common video data stream. That's why a simple DVI to HDMI adapter works. It's the same data.
However, once you change back to HDMI, you really have no DVI chipset actually in the loop anymore. So you're really going HDMI to HDMI with an adapter change "in the middle" (I know it's really at the end of the cable).
From a chipset standpoint, you're fine through 1080p. However, you now have two things working against you. The first is that the adapter will make a small electrical change in the cable properties and the second is that five years ago I don't believe there were any HDMI -> DVI cables that could transmit high speed HDMI data. Luckily for you, 720p/1080i can fit in the bandwidth of a "standard speed" cable, which is what I think you have.
So, it's the same bits with your setup for 1080i/720p - no difference at all (no lag or no latency or any difference). You can think of the adapter as simply an additional small cable length.
However, for 1080p I suspect your old cable won't be able to successfully transmit 1080p speeds. These require a "high speed" cable and yours isn't at 50 feet. The conversion from DVI --> HDMI just makes this more difficult but not impossible.
So, that advice to try it and find out is correct. However, I believe for 1080p you are looking at replacing the cable with something else since 50' is outside of the HDMI high speed specification. BTW, what you will see with 1080p errors are sparkles, no picture, solid lines, screens of a single color, etc. It won't be subtle. Remember these are digital cables, so if the 1s and 0s make it to the other end of the cable, the picture will be perfect. If you get errors they will be random errors in the picture resulting in large blocks of unusable data and not subtle changes like it's not as sharp.
And, yes, component video with good cabling will provide you the same picture for 720p/1080i. For 1080p, if there is a picture quality improvement, most people would not see it. For component video outputs, the picture is just converted from digital to analog at the component rather than at the TV.