Feature Article

The Value of Using an Outboard Video Processor with All Home Theater Video Displays

Part III

September, 2006

John E. Johnson, Jr.


Another issue that processors do a good job at is "Pixel for Pixel".

Pixel for Pixel settings are something that are just not in DVD players or displays. At least, not yet anyway.

What this term means is that the original video signal gets transferred to the display at the display's native resolution, exactly, pixel for pixel. So, if your display is 1,366x 768 pixels in resolution, the video processor can be set to deliver the video image at this specific output. The reason it is important is that it eliminates one additional step that the display has to otherwise complete, namely, scaling (converting) the resolution of the incoming image to its native resolution.

Now, since the signal off the DVD is most likely not the same as the display's native resolution, it has to be scaled somewhere along the line anyway, right? So, every digital display has a circuit in there to do this, but it is likely a chip that costs all of maybe five bucks. The circuits that process video signals in the $2,000 processor are much higher quality. Guess where it is better to do the scaling.

When you have the Pixel for Pixel setting correct, how do you know it's correct? Test Patterns, that's how. Video processors have a lot of them, and they are made specifically to test your settings on the various menu items. When it is set correctly, the test pattern shows it. Specifically, the Pixel for Pixel issue shows up as a continuous arrangement of smooth dots across the screen, and when it is incorrect, there are alternating patches of dark and light dots.

If you have several SD sources with component video outputs sitting next to that HD satellite box, like most of us do, video processors "Transcode" their component video signals to that 1,366 x 768 native resolution, and even 1080p, for the new 1080p LCD TV that you just bought.

Remember the Chroma Upsampling Error that Secrets investigated a few years ago? Because we talked about it so much, everyone became familiar with it, and we ended up naming it "CUE" for short. Well, it turned out to be a significant enough problem that a few DVD player manufacturers tried to correct it. Unfortunately, not all of them could fix this issue due to the chips they were using.

Enter the video processor.

Both the DVDO and Lumagen processors have CUE correction as part of their menu options, for example, in the screen shot below.

With the Lumagen, you go to Configuration and Color, to get to CUE Correction.

Hopefully, someday, all players will use video chips that don't have the CUE problem. But, until then . . . .

Another issue that was driving me crazy was the little bit of picture that was being chopped off the sides by the DVD player. I mean, if I am going to watch a widescreen movie at 2.35:1, I want to see all of it, not just 90%.

Video processors have Overscan and Underscan adjustments that let you fix this. Sometimes it requires changing something in the DVD player menu, and/or the projector menu to get it all to work properly. That is just the nature of the beast. If you want to fine tune everything, well, everything includes a lot of stuff.

While you're at it, you can set the Color Space, and I found that there was no way to tell exactly what was going to work best. Here, it is just a try it and see approach. It worked at YCbCr on one projector, but the next one I put in for test, required the RGB setting, as shown below.

I thought originally that HDMI would perform much better than DVI, but have not found that to be the case. Right now, all video is still 8 bit color (8 bits each for red, green, and blue, for a total of 24 bits). HDMI will handle 10 and 12 bit video signals, but we don't have any such signals from sources for it to handle at this point. Maybe a few years down the road.

So, it's probable that you have maybe a DVD player with DVI out, and a display with HDMI in. Video processors with either DVI or HDMI jacks on it should be fine. The only additional thing you will need are a few DVI/HDMi adapters. I use them all the time, and have never had a problem. They are pin for pin compatible.

Note that these two outboard video processors - indeed, all modern outboard video processors - have many more features and capabilities than I have mentioned here. Those features will be described in product reviews.

Several new SSPs and receivers are showing up with built-in video processing. We will compare their features and capabilities with those in the outboard processors.


So, are we excited yet? My guess is that you have been thinking about getting a video processor, and were waiting for that little nudge.

Consider the nudge made.

If I can set one of these things up, so can you. It solves all kinds of problems, and it makes a big difference in the picture. There's a lot more to watching TV these days than brightness, contrast, and color. The outboard video processor has become not just an accessory, but a necessity.

Go get one.

- John E. Johnson, Jr. -

Copyright 2006 Secrets of Home Theater & High Fidelity

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