Quantcast AVT-8710 chroma bug (green model) - digitalFAQ Forum
  #1  
09-04-2021, 04:22 PM
msgohan msgohan is offline
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Checkerboarding; Y/C crosstalk
AVT-8710 chroma bug demo.png

I've only tested this on Mitsubishi HS-HD2000U so far, but these steps reproduce the issue:
  1. Disable VCR blue back.
  2. Switch to analog tuner or any inactive line input. This garbage signal will prompt the AVT-8710 to display color bars.
  3. Play tape. If checkerboarding doesn't occur, hit stop, wait a few seconds, play again. "Rinse, repeat." It seems to happen a little less than 50% of the time.
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YouTube demonstration. x264 original resolution version of same video attached. I didn't deinterlace it, because the animation and video effects in this promo are actually 29.97p.

Workflow:
HS-HD2000U (+DNR&TBC, PPT Normal) <YC> AVT-8710 <YC> EVAL-ADV7842-7511P (7.5IRE) <HDMI> splitter <HDMI> C027

(Last year, I also reproduced it using a SAA713x as the capture card instead of the EVAL chain. I thought I'd figured out why ehbowen got checkerboarding in his MIB2 comparison thread, but he didn't use the AVT.)


Attached Files
File Type: mp4 AVT-8710 chroma bug demonstration.mp4 (17.20 MB, 2 downloads)
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  #2  
09-04-2021, 04:50 PM
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lordsmurf lordsmurf is offline
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I saw this at least 10 years ago. It doesn't affect all units, just some. The s-video cables also affects it, for whatever reason. It's easiest to see on cartoon animation, mostly on colors like yellow and red.

That checkerboarding you see there is horrible, the worst I've ever come across.

Just remember there is no perfect processing, no perfect TBCs. You want good/quality/best, not (unachievable) perfection. Something like this isn't a reason to avoid a green AVT-8710, but merely something to watch for.

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  #3  
09-04-2021, 05:27 PM
msgohan msgohan is offline
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Quote:
Originally Posted by lordsmurf View Post
Something like this isn't a reason to avoid a green AVT-8710, but merely something to watch for.
Yeah, I just wanted to document it since I came across this and determined the steps to trigger it.
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  #4  
09-04-2021, 11:02 PM
latreche34 latreche34 is online now
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That's a hot mess, Never seen that before, Does it output like that from the VCR or just after the AVT-8710?
Funny that you posted the same segment I posted before on youtube when I was experimenting about 720p and 1080p and youtube compression, Your tape condition appears to be better, mine had some chroma bleed from wear due to repeated playback in a daycare center:

https://youtu.be/kV57w6KSJCE
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  #5  
09-05-2021, 09:32 PM
NJRoadfan NJRoadfan is offline
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I can trigger this bug 100% of the time using the S-Video input and 240p video like the JVC blue menu screen (and likely a Super Nintendo if I had a S-Video cable for it). Composite input is unaffected. Never had the problem crop up with 480i video input.
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  #6  
09-06-2021, 02:57 PM
msgohan msgohan is offline
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Quote:
Originally Posted by latreche34 View Post
Does it output like that from the VCR or just after the AVT-8710?
Only with the AVT-8710 in-line.

Quote:
Funny that you posted the same segment I posted before on youtube when I was experimenting about 720p and 1080p and youtube compression, Your tape condition appears to be better
I saw when you posted it here and then I happened to see the same preview on my Canadian copy of the cartoon Dr. Seuss' How the Grinch Stole Christmas! dated 2000. Which tape did you use?

Quote:
Originally Posted by NJRoadfan View Post
I can trigger this bug 100% of the time using the S-Video input and 240p video like the JVC blue menu screen (and likely a Super Nintendo if I had a S-Video cable for it). Composite input is unaffected. Never had the problem crop up with 480i video input.
I wonder why the HS-HD2000U blue back isn't triggering it on mine. It's 240p. Here's its VBI compared to the Panasonic PV-S4266 blue back. No half-lines on the 240p.

HS-HD2000U VBI EVAL.png
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