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up-conversion -- dvd/receiver?

298 Views 4 Replies 3 Participants Last post by  gilunionhall
As someone new to the HT scene and still the the planning stages I have a question about "upconversion"

I have been looking at DVD players that have "video upconversion" and receivers that have "video conversion" (to component video)

Are we talking about the same thing?

The receiver conversion deals with any video signal to comes through it - even VCR's and standard definition TV signals?

If you run the DVD through the receiver, is there a problem with the software trying to do the conversion twice.


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Nope these are not the same thing. The DVD marketing guys saw a nifty term being used to describe a function of some A/V Receivers and appropriated it to describe an entirely different feature of some new DVD players without regard to the confusion they were causing.

Conversion or up-conversion in a Receiver is the feature that lets you send in a lesser quality style of video signal (such as Composite video) and have the Receiver convert it into a better quality video signal for output (such as S-video or Component video). The main difference between the signal types is the "bandwidth" of the signal -- particular the color signal -- which shows up as more saturated and natural colors using the better style of signal. Obviously the receiver can't invent information that's missing in the lesser quality signal, but this is a convenient feature none the less in that you only have to run one type of cable, say Component, to your TV even though you have Composite video connections coming in to your receiver from older source devices such as a VCR. Many Receivers up-convert from Composite video to S-video. Far fewer will also convert from Composite or S-video all the way to Component video. Usually the up-conversion feature is touted only for those more sophisticated receivers.

An up-converted signal should produce the same quality of image on screen as if you had connected it directly to the TV without up-conversion. That is, up-conversion has everything to do with convenience and nothing to do with image quality. But sometimes TVs have pretty crappy electronic designs for these lesser style video connections (see the furor in the Plasma forum about the goof-up Panasonic made with S-video connections for their latest Plasma panels for example), so having the Receiver up-convert and send a signal to the TV that the TV handles more professionally may, indeed, result in a visibly superior image even though the extra color data wasn't in the original signal to begin with.

The point is that we are talking about the type of video signal here, not the content of the signal such as its pixel resolution. The input and output signals have the same pixel resolution, gray scale, and color depth, even though the signal style to which you have up-converted is CAPABLE of carrying more information than was present in the original signal. To get the full value of the better signal type, you need to have the SOURCE device send that signal to the Receiver so that no up-conversion is needed and the full quality of the better signal can just be passed through.


In any event, the marketing guys thought that the term "up-conversion" sounded pretty nifty (who WOULDN'T want things converted in the "up" direction?), and came up with the bright idea to use it again to market an entirely different feature of new DVD players.

The correct term for what's going on in the new DVD players, however, is "up-scaling": The application of a "scaler" circuit to raise the pixel resolution of the video signal by applying math to the image (more or less cleverly) to extrapolate the extra pixels.

Receivers today don't include scalers (although God knows it's probably only a matter of time). There ARE devices out there called external scalers (DVDO's IScan and the Lumagen products for example), that will do this job, and most TVs today also have internal scalers. But the hot new item in DVD players these days is players that include a scaler in the player itself so as to raise the 480i resolution of current DVD discs up to the 720p or 1080i resolution that HDTV-ready TVs like.

The value of such scalers in DVD players is debatable since the TV is often capable of doing the same work itself. But many people have seen significant picture improvements by using such up-scaling DVD players -- sometimes for reasons that have little or nothing to do with the up-scaling itself.

For the basics of what's going on here with DVD players today, what determines whether the image will be better, and why "up-scaling" DVD players may or may not be a good thing for you, see the following "primer" thread:


As you'll see in that thread, the issue of doing something twice here actually arises because the image is scaled once by the DVD player and then again by the TV. There's no particular problem here except that each time you process the signal you add the possibility of making mistakes.

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Although I must note that there are avr receivers that deinterlace 480i to 480p such as the HK 7300 that uses Faroudja processing. I think the Denon 5805 does this too and possibly even upscale 480i to 720p/1080i.
Yup, according to Crutchfield the Denon 5805 Receiver up-scales on it's Component outputs (but not on it's digital video outputs). I told you it would only be a matter of time! :D

Of course Crutchfield calls that up-conversion as well. Fighting marketing-speak is a losing battle....

hello bob -

you have made things clearer for me. i will also go to the "DVD primer" thread and do some reading there.

thank you very much for taking the time to write out a very useful and understandable explanation!!

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