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Discussion Starter · #1 ·
Hello to all and I hope this in on-topic.


I'd guess that the chips in MPEG satellite receivers including 4DTV have the chroma bug. My guess is that they are the same chips as used in DVD players.


Has anyone here info on that?


Many thanks in advance and regards.


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Pablo Roufogalis L.

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I know Echostar had some problems with some of their DBS receivers a couple of years ago before anyone even knew what the chroma bug was (they called it the red jaggies) so it is concievable that others would as well.
 

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However, since the chroma bug is related to deinterlacing, it should only be visible on 720p, 480p, not on 1080i or 480i. Although, you can still have stairstep, jagged lines due to subject motion, independently of the chroma bug.
 

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Actually steve you are incorrect. The chroma bug is in no way related to interlacing or de-interlacing. It is only related to mpeg decoding. That includes mpeg 1 and 2 at any resolutoin interlaced or not.


As far as sat recievers using technology like prog dvd players they already sorta do. All those recievers that upconvert 480i to 1080i are all trying to get the best picture quality output on HD Screens. The actual quality veries from reciever to reciever but some probably give you about the best picture quality you can get from the highly compressed DSS Signal.
 

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For those who just heard about this for the first time (or couldn't remember what it was - like me), look here and search for "Chroma Upsampling Error".


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[This message has been edited by Man E (edited 09-21-2001).]
 

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The chroma bug on dss receivers is very real and as mentioned, is not dependant on progressive or interlaced signals. And trust me, it looks just AWFUL on a big screen.


I've got a regular old RCA DirecTV receiver and the bug is VERY evident. I have been trying to get data on what HD receivers do not have the bug, but can't seem to find any information. If anyone knows where I can get said info, I'd be very grateful.



[This message has been edited by Mattrazzo (edited 10-03-2001).]
 

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Quote:
Originally posted by Savageone79:
They probably all have it.
Well, we know that not all DVD players have it. This is based on different MPEG decoding hardware. Do all DSS receivers use the exact same MPEG hardware?


By extension, do all HDTV receivers have the same problem? This I would find hard to beleive since on my 73" the chroma bug screams at you with a DSS or flawed DVD signal. Yet I have seen HDTV demos that were (for practical purposes) perfect. I do not yet have an HDTV decoder, but if all of these also have the chroma bug, I hesitate to slap down money for a broken piece of hardware.


For DVD I plan to go to HTPC, but for satelite I don't have many choices. For HDTV, I'm looking at the telemann card for the HTPC...


So does anyone know where I might find these answers? I feel like I've been asking everyone, in many different forums and in person, and no one seems to know...
 

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If the HD Part has it to it isnt noticable at all probably having to do with the high resolution of it compared to dvd's or regular dss tv. I am thinking they all use the same mpeg hardware but I could be wrong. Anyway it's not very bad and i hardly ever notice it on mine so i dont really think its worth worrying about.
 

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Quote:
Originally posted by Savageone79:
If the HD Part has it to it isnt noticable at all probably having to do with the high resolution of it compared to dvd's or regular dss tv. I am thinking they all use the same mpeg hardware but I could be wrong. Anyway it's not very bad and i hardly ever notice it on mine so i dont really think its worth worrying about.
That's a good point. Possibly the bug is hidden in the high-resolution image. I know at 480p off my DirecTV receiver, it screams at you. Huge double lines around boxes for TV graphics (like on CNN), and overall graininess. From my assessment (totally subjective), the graininess is at least partially due to the chroma issue.


So, I won't bother to debate how noticable it is, because everyone seems to differ on this (A buddy of mine has a 100" screen and he says he can't see it). So, it sounds like your recommendation is to go get an HDTV DSS rcvr and don't worry about the bug...?
 

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Discussion Starter · #14 ·
Quote:
Originally posted by Mattrazzo:
So does anyone know where I might find these answers? I feel like I've been asking everyone, in many different forums and in person, and no one seems to know...
Perhaps someone that knows about the actual chips can help you.


Why, there's always the chance that newer chips without the bug can be exchanged for the one in your box.


Good luck and let us know.


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I'm not sure how appropriate this is here, or if I should resurrect an old topic, but I just experienced this myself on an (older) Echostar receiver.


I had a 4700 receiver that was working fine, but hadn't gotten a software update for a while. Dishnetwork tech support decided it was hopeless (Non-Downloadable Unit) and would have to be swapped out. They sent me a refurbed 4900 unit to replace it, and I noticed that something was wrong with the picture within 5 minutes. It took me another 10 minutes to figure out it was the chroma bug (red jaggies) discussed above. I.e., red round buttons on their Help channel all had jaggy edges. Large red circles had horizontal daggars going off on both sides. Large red areas had banding.


Surprisingly, Dish tech support did not seem to be familiar with this problem, and after running me through the ringer with their standard diagnostic procedures (pull the card, pull the plug, yada yada) they seemed at a loss. Only when I told them (again) that the video glitch was only on the 4900 they had just sent me, and NOT on my 4700 unit, did they decide it must be defective.


So, they're sending another replacement unit, but at this point I'm rather apprehensive that it may have the same problem. In fact, it's possible that ALL the 4900 series could have the problem, for all I know. And this video defect is NOT subtle, even on a 32" screen, and is totally unacceptable. I'm concerned that after sending out two replacement units at their cost, Dishnetwork will say there's nothing more they can do.


Has anyone else run through this scenario with Dish? If the new unit has the same defect, my only options would appear to be to go out and buy a newer receiver, and hope they don't have the problem; or terminate my Dish service (which the wife will be none too happy about).


- Tim
 

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I can confirm that my Starchoice box has had the chroma problem for the past two years. I don't know if their newest boxes have it or not.


On a related note, I've seen a Zenith DVD player that has the chroma bug in the Zenith logo that appears when you turn on the player. Don't even have to try a movie to see it!
 

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The chroma bug shouldn't be in any way relevant to HD, because there is no such thing as a chroma subcarrier in HD. The HD signal is created directly from three RGB components though a hellishly complicated scheme of compression, randomizing, and so forth. At the receiver, the three RGB components are directly re-constituted from this statistical mass.


The chroma subcarrier is strictly a creature of compatable analog systems like NTSC and PAL (SECAM actually has two subcarriers, transmitted in sequence) and the red jaggies come from compression/decompression hardware that loses some of the subcarrier content.
 

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The "chroma bug" has definitely been seen in HD recievers (at least for the MyHD and HiPix PC cards). It apparently comes from an error made during the upsampling of the chroma data during MPEG de-compression. It is a lot less visible than what you see on DVDs since it is on the single-pixel scale, and pixels are a lot smaller in HDTV for a given display.
 

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Quote:
The chroma bug shouldn't be in any way relevant to HD, because there is no such thing as a chroma subcarrier in HD. The HD signal is created directly from three RGB components though a hellishly complicated scheme of compression, randomizing, and so forth. At the receiver, the three RGB components are directly re-constituted from this statistical mass.
I thought ATSC HDTV was MPEG-2 compressed YUV. No? Why would they want to go direct from RGB?
 

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Quote:
Anyway it's not very bad and i hardly ever notice it on mine so i dont really think its worth worrying about.
HA! Doubtful....I had a E* 4900 receiver and I was watching a NASCAR pre-race show....They had Elliot Sadler (Red Motorcraft 21 car) on for an interview. He had his red fire suit on.....Well, he looked like a big blob of red on the screen....it was just plain awful and annoying....I showed my wife the show and she noticed how terrible it was....From there, every instance of large amounts of red showed the bug....


It just depends.....But its *very* noticeable once you know what you are looking for...
 
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