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Discussion Starter · #1 ·
While watching Alias tonight I saw some odd blue sparkles in the lower half of the screen. The upper half was unaffected. These were only obvious during darkened scenes, but in Alias most of the scenes are darkened. I was watching from SF, then switched to Sac to watch The Practice and they weren't evident there.


Did anybody else in the Bay Area see this?


First the Unity Motion shows red sparkles, now this. Here I thought HD signals weren't subject to some sort of interference.


Chris
 

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This has been reported here in the past, but for some reason I can't find the old thread. I used to see it, exactly as you describe, but only on our ABC affiliate, and only on HD. Since I changed monitors, I can't see it any longer, but that doesn't mean it isn't still there. When I reported it in the past, others said they also see it in other cities, but only on ABC.
 

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Chris:


I watched Alias with my Unity Motion and did not see any blue sparkles on my display (Toshiba TW56X81).
 

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Aviators99,


The "blue sparkles" still show up during dark scenes, not only on "Alias" but on practically every single HD show broadcast on WPLG-ABC. I've e-mailed their chief engineer in the past about it, but never received a response. This weird phenomenon made all of the night sequences in the Bond movies almost unwatchable. I would be very interested to learn what causes it.


Rudy
 

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Discussion Starter · #5 ·
Rudy,


Are the sparkles you are seeing on just the lower half of your screen? That was the odd part...it only affected the lower half.


Perhaps it's not ABC or their affiliate Rudy....perhaps it's just a few of us with some unknown interference causing this. I see red sparkles all over the screen while watching anything from the Unity Motion/4DTV combination.


Chris
 

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Is this receiver-specific? I didn't notice any sparkles during Alias (I did get a few audio clicks and pops). Using SIR-T150.
 

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Discussion Starter · #7 ·
I was using the Hipix to watch Alias last night off Sutro. Funny, I didn't hear any audio clicks or pops, but I did have two audio dropouts.


I'm beginning to think I have some terrestrial interference getting into something. It's not like this was subtle and others wouldn't see it....it was very obvious.


Chris
 

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I watched it on KGO last night, via a HiPix, and saw no sparkles. I had a couple of dropouts, but that's normal for me for KGO.
 

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Quote:
Originally posted by R8der
Rudy,


Are the sparkles you are seeing on just the lower half of your screen? That was the odd part...it only affected the lower half.


Perhaps it's not ABC or their affiliate Rudy....perhaps it's just a few of us with some unknown interference causing this. I see red sparkles all over the screen while watching anything from the Unity Motion/4DTV combination.


Chris
Chris,


The sparkles tend to appear in the areas of the screen that are the darkest; I've seen them in both the upper and the lower part of the screen. Also, I've noted that when they appear, they form a band that runs across the entire screen...but they're just not as visible if there's also light areas within the band of sparkles. And if the dark scene is very brief, you hardly notice them at all.


I first saw these sparkles with my RCA DTC100, then subsequently with the Samsung SIR-T150. I've never seen them on any other digital channel, only on our ABC affiliate. And they do not appear when the program being broadcast is upconverted NTSC as opposed to HD. You may be right about the interference theory, but I thought DTV was immune to this sort of thing.


Rudy
 

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I checked in on Notting Hill on ABC tonight (KGO from Sutro). I saw none of the blue sparkles we saw last night during Alias. It was also there during Stewart Little and The Practice. This is really weird.


jeff
 

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We noticed these at my house during Alias as well. HiPix with Sharp 9000 projector, from KGO via Sutro tower. They were not noticeable enough to bother me, and I don't recall noticing them before.
 

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Something to do with 720p broadcast conversion?
 

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I thought KTVU was sending 480p.
 

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this is what I was looking for...

Regarding KTVU-2's digital broadcast, this is a recent e-mail from an engineer at KTVU:


"Fox Prime-Time (8-10 PM) is a digital signal, sent to KTVU in the 480 format and transcoded to 720P for transmission by KTVU. Some fox programming during that time (8-10 PM) is in 16 x 9."


"Transcoding is taking a pure "Digital all the way" signal from Fox...notice we are not adding any local commercials yet to keep it pure... Our input is a 480 that has been configured in such a way that we "Unwrap" it, stretch it to 16 X 9 and re-encode it at 720P for broadcast. If you see what we broadcast just before 8 PM then just after 8 PM, check for the difference in quality. the first is upconverted, the later Transcoded."
http://www.avsforum.com/avs-vb/showt...u&pagenumber=3
 

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Ah, neato! Okay, that's nice to know.


Speaking of SF locals, I have two questions:


1) Anybody know how to reach the Engineering department at KBWB? The "feedback" system on the web page sends an email that bounces with "unrecognized recipient".


2) Anybody know what KBWB is using to do their upconverts? Smallville looks AWESOME!
 

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Just noticed this thread. I have a theory about the blue sparkles -- I believe they are caused by noise clipping. I hate to see the detail in shadows clipped away like that, but I've seen it in many HDTV productions and DTV broadcasts. Anyway, with noise clipping, stray pixels of noise will exceed the noise floor, and appear as sparkles. And the blue channel is usually the one that gives CCDs have the most trouble in terms of noise.


This is just a theory, but I'd be interested to know how close it is to the truth.
 

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If the noise clipping theory is true, then it is not applied to all programming. For example, in this weeks showing of Notting Hill, I noticed no sparkles. Same goes for the CBS monday night line-up. Tuesday nights NYPD Blue (ABC) looked fantastic. Last night's ABC HD line-up also appeared sparkle free. We'll see what tonight brings. Also, I guess Dinotopia will be 720p so we'll see if it has or has not sparkles.


I guess the question really is, where in the process do the sparkles get introduced? This probably would have bearing on why some shows and other do not have it.


jeff
 

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I also noticed the sparkles during the Stuart Little broadcast last weekend. While I have no idea what causes this, judging from the locations of the posts on this subject, it appears not to be a local issue.


Dennis
 
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