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Video gurus please HELP identify these chroma artifacts

392 Views 5 Replies 3 Participants Last post by AVfile, Feb 24, 2005

AVfile

Discussion Starter · Feb 22, 2005

There is a problem with the LINN Unidisk SC (latest version) in progressive scan NTSC mode. I have identified it in two brand new samples of the player and on two different displays including a calibrated CRT and a plasma. Linn says they can't reproduce the problem over in Scotland.

What's wrong with this picture?

http://members.rogers.com/sdrever/USC_AVIA.jpg

In the red, green and blue text "AVIA" you can see jagged distortions that look like a sawtooth wave. Also very noticeable on the red WARNING screen that appears when you load the disc.
In the purple letters you can see a red shift, which appears to be a serious chroma delay.
In the top right corner the blue "Select" button also shows chroma delay.
If I switch the Linn to interlaced mode, the jagged waves are gone and most of the chroma delay is gone.

Example of red and green shift in yellow text:

http://members.rogers.com/sdrever/Advanced_AVIA.jpg

There is also some ugly blocking or jaggedness there.
It occurs on playing film (eg: yellow credits) not just in menus.

Chroma delay is obviously huge:

http://members.rogers.com/sdrever/YC_Delay.jpg

But I'm hoping someone has seen these symptoms before, and we can better identify it and report back to Linn. Is it a software problem, hardware problem, multiple problems, 3rd party chipset problem (it uses ESS) or an NTSC/PAL issue they may have trouble testing overseas?

I'm also getting so much pixel cropping of the top rows that my overscan is very uneven (this is on my CRT so ignore some overscan, but confirmed on fixed pixel display):

http://members.rogers.com/sdrever/Overscan.jpg

http://members.rogers.com/sdrever/Pixel_Crop.jpg

Could that be a horizontal scan rate problem?

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AVfile

Discussion Starter · #2 · Feb 24, 2005

Any comments?

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Paul Bigelow

· #3 · Feb 24, 2005

Hello,

The Y/C delay is obviouly huge so that might partially explain the green fringing.

The patterns being displayed for pixel cropping are native 4:3 (Avia) and are being stretched to 16:9.

What are the resolutions of the displays? 1280x768 or 1280x720? Other? If 1280x768 some cropping may occur as result of the display.

What is the result from another player with the same display? Could the Linn player be defective?

Best regards,

Paul

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AVfile

Discussion Starter · #4 · Feb 24, 2005

Hi, thanks for the reply...

Quote:

Originally posted by Paul Bigelow

The patterns being displayed for pixel cropping are native 4:3 (Avia) and are being stretched to 16:9.

That's OK, as horizontally it's fine (my overscan swamps it but it is at least even). Vertically, even though my CRT is overscanning most of the test pattern, you can see that it is uneven. When viewed on my dealer's plasma, the overscan is almost nil, and you can clearly see it is cropping about 13 rows more on the top.

Quote:

What are the resolutions of the displays? 1280x768 or 1280x720? Other? If 1280x768 some cropping may occur as result of the display.

Well my CRT is native 480p. Not sure what the res of the plasma was but the cropping is uneven. The picture is shifted up similarly on my CRT, albeit with more overscan. For example on 2001: A Space Odyssey (2.20:1) the top letterbox bar is gone, but not the bottom one!

Quote:

What is the result from another player with the same display? Could the Linn player be defective?

I've had this TV for years and had no problems with two other DVD players. In the store we connected a different Linn (Unidisk 2.1) and it was near perfect!

The Unidisc SC is defective IMO.

Cheers,

Stefan

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