[KMO]

Just been niggled by a geometry error in my Denon DVD-3930's upscaler - it helpfully scales an entire 720x576 DVD frame up to 1920x1080, despite the fact that the SD frame is wider than 16:9, leading to a 2%-too-thin picture.

(My TV had an equivalent geometry error - 576i and 576p inputs being too narrow, but it can be corrected in the service menu).

So, which separate scalers get this right - scaling up just the central 702x576 16:9 image area, or can be configured to? The Radiance XD/XE looks like it can be manually configured to crop the edges correctly, or to whatever you like. What about the rest?

[Avi]

Originally Posted by KMO

Just been niggled by a geometry error in my Denon DVD-3930's upscaler - it helpfully scales an entire 720x576 DVD frame up to 1920x1080, despite the fact that the SD frame is wider than 16:9, leading to a 2%-too-thin picture.

(My TV had an equivalent geometry error - 576i and 576p inputs being too narrow, but it can be corrected in the service menu).

So, which separate scalers get this right - scaling up just the central 702x576 16:9 image area, or can be configured to? The Radiance XD/XE looks like it can be manually configured to crop the edges correctly, or to whatever you like. What about the rest?

Is your display running in 1:1 pixel mapping mode ?

AVI

[KMO]

Hmm? For 1080p input, yes.

Which is kind of the point - if the TV is perfectly calibrated so that circles from 1080p input are circular, then circles from my upscaled DVDs aren't, due to the DVD player's upscaler not preserving the geometry of the 576i signal.

The TV has independent scaling controls for each input resolution , so its own 576i geometry glitch can be fixed. But the TV's deinterlacer and scaler are not brilliant quality, so I'd rather upscale in the DVD player (and in future in an external scaler) - but I then I want that scaler to get the geometry right.

The error occurs because kit incorrectly assumes that the 720x576 frame is exactly 4:3/16:9. It isn't. It's a little bit wider, basically to pick up analogue slop when digitising analogue video. Whereas the 1920x1080 frame is exactly 16:9.

Good explanation from the BBC here: BBC - Commissioning - A Guide to Picture Size

If a player is outputting a DVD at 576i/p, it should stick the 720x576 or 704x576 DVD image into the 720x576 HDMI signal with 1:1 pixel mapping (inserting bars for 704), and it's up to the display to realise that it should only worry about the middle 702.

But if the player (or any other upscaler) is converting to 1080p, it's got to take only the middle 702 for the scale, otherwise the 1080p signal will end up with cruft on the edges that shouldn't be there, and it'll be too thin.

The relative distortion is quite visible via DVE DVD & Blu-ray geometry checks, although the DVD test cards aren't very clearly marked for the necessary crop.

[Avi]

Originally Posted by KMO

The relative distortion is quite visible via DVE DVD & Blu-ray geometry checks, although the DVD test cards aren't very clearly marked for the necessary crop.

A bit confused how this would affect Blu-ray geometry if it's related to DVD upscaling in your Denon DVD player.


AVI

[KMO]

No, I mean you can compare the two. The DVE Blu-ray clearly demonstrates that you've got 1:1 pixel mapping for 1080p, and that circles for 1080p are circular.

And then you use the DVE DVD to show that DVDs upscaled to 1080p have a distortion.

[KMO]

Okay, a bit of trudging through manuals suggests that the DVDO Edge, VP50 and VP50Pro all have a per-input horizontal scale option that would correct this issue, if necessary.

I assume this is a fairly fine-grained control. Any unpleasant artefacts for small horizontal zooms when going to 1080p?

[Avi]

Originally Posted by KMO

I assume this is a fairly fine-grained control. Any unpleasant artefacts for small horizontal zooms when going to 1080p?

The horizontal zoom starts at 0.6% and increments in steps of approx 0.6% so relatively fine.

AVI

[KMO]

Thanks - but on what box? The Edge?

4 steps = 2.4% ~= 17 pixels would be about right.

[Avi]

Originally Posted by KMO

Thanks - but on what box? The Edge?

4 steps = 2.4% ~= 17 pixels would be about right.

The Edge.

AVI

[KelvinS1965]

On my Lumagen HDQ there are size settings available on the input that can trim the area of the signal in pixel steps (at least that's what it seems to do when I set it up). The 1080 output can then be sent to a 1:1 pixel mapped TV/PJ keeping the correct shape. The upscaling is also much better than my BluRay player or projector. However the HDQ/HDP are old models (though still well supported by Lumagen) and have DVI inputs. The plus point being that you can pick them up much more reasonably than their new cost (I think there is a HDP for sale in the classifieds ATM).

[KMO]

Thanks! The HDP doesn't have automatic aspect ratio switching though, does it?

Amazing how these expensive, dedicated video processors can't manage the simplest widescreen video processing function of all.

I can picture the marketing...

"Bored with how your widescreen TV effortlessly switches between 4:3 and 16:9 inputs? Try our new video scaler, and you too can enjoy the thrill of faffing around with the Aspect button every time you change channel or the adverts come on. Buy one today!"

[Avi]

Originally Posted by KMO

Amazing how these expensive, dedicated video processors can't manage the simplest widescreen video processing function of all.

Some do.

AVI