Pixelation and Signal Meter Question

[iGen3]

Hello,

I have a few questions on a new Directv setup and I'm hoping you can shed some light on a few quality issues I've been experiencing.

To summarize: I live in a condominium of around 72 units and have just recently had Directv installed. The building has one dish mounted on the roof and the building was wired originally to handle Cable, Directv, and off air antenna for Directv. We have a contracting company that does all the DBS duties and they completed the MPEG4 conversion about a month ago and I switched over from Comcast. They informed me they utilize a system so that each unit needs only a single cable run and still be able to utilize the DVR functionality. They also noted they were happy that the builder ran good cable as they requested when the building was built. (RG22 sound right? I think that's what he mentioned, not familiar with coax.) I am using the HR21 box hooked up to a Pioneer 5010 with HDMI. I know there are no problems with the TV or cable as I had Comcast installed here for 3 years and picture quality was incredible.

I am noticing a lot of pixelation on particular channels. The worst culprit is Lost on ABC, dark scenes show unacceptable pixelation - this is micro level movement in the picture, not big blocks of green as others sometimes refer to, but I have that issue as well. There also seems to be pixelation between scene transitions and then it sharpens after a few seconds. Bright scenes don't seem to have any problems and look good. There is also anoticeable breakup of programming on all stations, with large blocks showing up here and there. A few stations actually show no problems at all and look great. (YESHD, Food Network HD) Another issue I've been having is that the receiver has stopped during viewing, changed to a black screen, then reboots. This has happened 3 times in two weeks. Overall, I just think the PQ is lacking the wow factor that I had with cable.

I will be contacting the contractor to discuss these issues, they are very helpful and I'm sure will get it right. I wanted to post my signal meter reads to you all to see if you can shed any light on what might be causing the problem. I know people talk of Directv not having a enough bandwith and they compress their signal, but I thought MPEG4 was supposed to get rid of all that. I wouldn't mind having a little information on my end to know what could be the problem, I have a few meters in the 60's and 70's and don't think that's right. I didn't know if also perhaps ABC was on transponder with weak signal.

Thanks for any help you can provide in advance. Should I be asking the contractor any specific questions?

Satellite transponders (32 total at 101-deg)
1-8 97 97 97 75 95 100 96 100
9-16 95 97 96 80 94 100 95 100
17-24 89 100 94 69 94 100 95 100
25-32 91 91 96 0 95 100 92 100

Satellite transponders (3 total at 110-deg)
1-8 NA NA NA NA NA NA NA 95
9-16 NA 92 NA 95 NA NA NA NA

Satellite transponders (11 total at 119-deg)
17-24 NA NA NA NA NA 99 0 97
25-32 0 99 97 99 0 100 97 100

Satellite transponders (6 total at 99(s))
1-8 62 88 75 90 0 65 NA NA
[Note: these can be very slow to appear]

Satellite transponders (16 total at 103(s))
1-8 0 0 0 0 0 0 NA NA
9-16 NA NA NA NA NA NA 89 97
17-24 92 0 98 96 0 0 85 95
[Note, these can be very slow to appear]

Satellite tranpsonders (16 total at 103(c))
1-8 94 91 89 87 88 89 85 86
9-16 84 88 84 91 88 92 NA NA
17-24 92 NA NA NA NA 94 NA NA

[K4SMX]

I don't see any obvious problems with those signals, but how about the signals on tuner 2? Please report any obvious discrepancies. And what are your neighbors seeing re: the pixelation you're seeing?

BTW, the signals on 99(s) and 103(s) are all spot beams, so the signal strengths can be all over the lot on those two satellites. D. C. is supposed to be on 99(s), but could've been moved to the DirecTV10 satellite, which appear in the lower half of the 103(s) table. If they're still on 99(s) in whole or in part, they're probably on tp 4.

Welcome to DBSTalk.com!

[litzdog911]

Your signal levels look great, so I don't think it's a dish or reception issue.

Can you post a photo? Your description sounds like it could be the "typical" MPEG compression artifacts that we all see sometimes.

[K4SMX]

I don't like those black-screen spontaneous reboots. With those signals, he probably needs a new receiver, although there can still be hidden LNB issues. That's why he needs to poll his HD receiver-leasing neighbors.....

[iGen3]

Thanks for the replies. The #2 tuner is right on par with everything I posted for tuner #1. I will try to get a few photos this week, but I'm afraid I think that I'm just seeing what is normal for Directv? I keep reading about Directv's HD lite, downconverting the resolution that was just approved by FCC, etc. There are only a few people who have the new MPEG4 equipment and they are not too particular unfortunately. I don't think they would even notice as their sets are still in torch mode from the factory. Oh well, the only real reason I got Directv is so I catch watch the Yankees in HD, so I'm happy. If this reboot issue continues, I will see if they can swap out the box.

[breevesdc]

This is a great post. I'm having the exact same issue (and it is most noticeable on the exact same show... "Lost"). In particular, it seems to be very bad during dark scenes or scenes that are somewhat bright but where there is a colored background which is out of focus. I also noticed the same problems during NBC programs like "Heroes" and "Journeyman". I have also noticed minor problems that are similar (and perhaps related) on the local CBS channel during the NCAA tournament games.

If you still have "The Other Woman" episode, replay the first few minutes. There is a scene where Ben is showing Juliet her new house. Juliet turns to look at Ben and says something like "This is too much... I'm only going to be here 6 months". In the background (in this fairly bright scene) the macro blocking of the yellow wall of the house is absolutely horrendous.

I spent a considerable amount of time trying to determine the source of the problem. After numerous tests, I've tracked it down to the HR20 or the actual signal from D*. My HR10-250 had no such problems. But I was getting my locals OTA on that receiver, so D* would not be an issue there. I've gotten frustrated to the point that I switched to OTA over this past weekend (I'm using an HR20 with an OTA input). The NCAA games looked significantly better. I'm going to record "Lost" on Thursday even though it is a repeat to see if the issue goes away.

I'm not making a conclusion here... But I wanted to let you know that I've been doing some reading on DBSTalk. And I have found several posts talking about "macro blocking" (which I believe is the problem you and I are both having) and the fact that D* HD channels are more prone to this issue due to bit-starving. I'll try to dig up the post I was reading this past Friday and add a link to it in this post.

I'm no expert. But as I understand it, D* compresses the feed from your HD local, transmits it to you, and your HR2* decompresses it. As a result, it is not full-bandwidth and some picture quality is lost. And thus macro-blocking becomes an issue. From what I've read, it is expected to get better over time as more bandwidth is made available (and less compression is necessary). But who knows how long that will be. I got impatient and switched to OTA just yesterday. We'll see Thursday night whether or not my impatience pays off.

Regardless, as an HR21 user, OTA is not an option for you (at least not until the AM21 comes out). But, I thought I'd provide this information based on all of the time I spent tracking down the source of this problem. Good luck.

Brian

[K4SMX]

While I'm no videophile, I can tell you I have examined my mpeg4 local's compared to their OTA versions very closely, and I can detect a slight difference in favor of OTA PQ when viewed at 3'. At normal viewing distance, I can't see the difference. From what I gather, DirecTV is using 1440 x 1080 for mpeg4, but that's definitely "third stool down" information. But if true, you could call it "HD sorta Lite." Whatever, it looks pretty good from 10' away.

That's not to say, however, that there's not some rather sophisticated technology at work here to obscure previously obvious macro-blocking. With the capacity that DirecTV will soon have available, there should be little need for any further HD signal degradation, but I don't think we're ever gonna get a full bandwidth, 1920 x 1080 signal from DirecTV or anyone else except possibly FIOS. Such is the current state of HD in the US.

Contrast that with the cable companies, who are now starting to cram 3 HD signals instead of 2 into one QAM channel. This is going to result in very definite PQ degradation. See for example: Comcast HD Quality Reduction: Details, Screenshots (http://www.avsforum.com/avs-vb/showthread.php?t=1008271)

That said, there are a number of weak points in the DirecTV HD locals architecture which are pretty much isolated to specific stations and/or DMA's. You can read a lot about those here. Improvements are being made in many areas, according to DirecTV press releases. I'm fortunate to have few problems, but I do have OTA + basic cable w/HD locals as a backup for the infrequent problems. For more specific info on your location that you don't find here at DBSTalk.com, check the local TV reception thread (http://www.avsforum.com/avs-vb/showthread.php?t=453241) for your area at AVSForum.com.

[breevesdc]

It's possible that this is a combination of signal compression by D* and the source of the signal... notice that we are both in the Washington, DC market. WJLA (the local ABC affilliate) has been known to have several HD issues over the years. Just an additional thought.

Either way, I will post an update on Thursday night to let iGen3 know if my macro blocking goes away. If so, I would definitely recommend getting an AM21 (as soon as they are available) and utilizing the OTA feed in combination with the D* feed.

I do 90% of my (HD)TV watching via locals. So for me, this potentially will solve 90% of my problems with macro blocking.

Brian

[iGen3]

I agree, I'm going to make sure they leave up the OTA antenna and I will utilize the AM21 to alleviate the problem. I look forward to seeing if it makes a difference this week for you, it should because the Comcast Lost (same WJLA)broadcast was flawless. An interesting note is that Lost is one of the few dramas that is shot in 720p which uses less bandwith than 1080i. If the 720p show is struggling, what does that tell you about everything else?

[Slip Jigs]

I've been plagued by macroblocking, or pixelation, on and off for over a year, but currently things seem to be fine.

This has ranged from the occasional brief moments, to more frequent with audio loss to complete picture freeze up. The symptoms are identical to rain fade effect - but without the rain, and it never gets to the searching for sat signal, like a rain fade will eventually do. Tuners also report good levels.

There are potentially many causes that can occur all the way back to the source - but in my case, even tho I've had many things done, my gut tells me that it was mostly cabling issues. The last tech I had out found a bad cable by measuring the signal at the dish, the splitter (I don't have a multiswitch), and then at the end of the run. The signal level showed a slight drop between the splitter and the receiver. The signal level by itself was still techically strong enough, but the drop showed there was something going on with the cable to cause this drop - and this introduce interference or a short that caused the problem. And it only showed on certain channels, because those frequencies, or whatever, are just more sensistive.

[K4SMX]

.....There are potentially many causes that can occur all the way back to the source - but in my case, even tho I've had many things done, my gut tells me that it was mostly cabling issues. The last tech I had out found a bad cable by measuring the signal at the dish, the splitter (I don't have a multiswitch), and then at the end of the run. The signal level showed a slight drop between the splitter and the receiver. The signal level by itself was still techically strong enough, but the drop showed there was something going on with the cable to cause this drop - and this introduce interference or a short that caused the problem. And it only showed on certain channels, because those frequencies, or whatever, are just more sensistive.
"A splitter." Hmmm. Are you on a Single Wire Multi-switch (SWM)? It appears that iGen3 is on a SWM.

[Slip Jigs]

"A splitter." Hmmm. Are you on a Single Wire Multi-switch (SWM)? It appears that iGen3 is on a SWM.

I guess splitter may not be the correct term. It's just a junction to connect the cables coming in off the dish to the cables going into the house. Only 4 total.

[K4SMX]

I guess splitter may not be the correct term. It's just a junction to connect the cables coming in off the dish to the cables going into the house. Only 4 total.
Right. That's a grounding block, and they can go bad.

[iGen3]

Right. That's a grounding block, and they can go bad.

Yeah, there is defintely something wrong. My box is resetting twice a day now (when I'm watching which is only probably 4 hours max). Also today, the program guide has shown no information available for every station all day. This is such a pain, I hope they can find the problem quickly.

[breevesdc]

It's possible that this is a combination of signal compression by D* and the source of the signal... notice that we are both in the Washington, DC market. WJLA (the local ABC affilliate) has been known to have several HD issues over the years. Just an additional thought.

Either way, I will post an update on Thursday night to let iGen3 know if my macro blocking goes away. If so, I would definitely recommend getting an AM21 (as soon as they are available) and utilizing the OTA feed in combination with the D* feed.

I do 90% of my (HD)TV watching via locals. So for me, this potentially will solve 90% of my problems with macro blocking.

Brian
Watching "Lost" now. The picture is incredible with no macro blocking whatsoever. The night time scenes look especially good compared to the picture quality I was getting with the HD locals provided via satellite. I'm sticking to OTA until D* resolves their issues with the new MPEG4 locals. There is no question that my OTA picture is substantially better than the sat-provided ones. Now if only I could get SciFiHD via OTA. :)

Brian

[iGen3]

Watching "Lost" now. The picture is incredible with no macro blocking whatsoever. The night time scenes look especially good compared to the picture quality I was getting with the HD locals provided via satellite. I'm sticking to OTA until D* resolves their issues with the new MPEG4 locals. There is no question that my OTA picture is substantially better than the sat-provided ones. Now if only I could get SciFiHD via OTA. :)

Brian

Thanks, I hope my contractor will keep the OTA antenna up there and I guess I'll have to get the AM21 when it comes out for my box. I have been talking to Directv and the contractor and this is the biggest pain the ass to resolve, my guide is still showing To Be Announced for every channel so I can't tell what's on and my DVR won't record anthying. They are each blaming each other. I just want my cable back and will order the baseball package in SD.

[TomCat]

This is a great post. I'm having the exact same issue (and it is most noticeable on the exact same show... "Lost"). In particular, it seems to be very bad during dark scenes or scenes that are somewhat bright but where there is a colored background which is out of focus. I also noticed the same problems during NBC programs like "Heroes" and "Journeyman". I have also noticed minor problems that are similar (and perhaps related) on the local CBS channel during the NCAA tournament games.

...I have found several posts talking about "macro blocking" (which I believe is the problem you and I are both having) and the fact that D* HD channels are more prone to this issue due to bit-starving. I'll try to dig up the post I was reading this past Friday and add a link to it in this post.

I'm no expert. But as I understand it, D* compresses the feed from your HD local, transmits it to you, and your HR2* decompresses it. As a result, it is not full-bandwidth and some picture quality is lost. And thus macro-blocking becomes an issue. From what I've read, it is expected to get better over time as more bandwidth is made available (and less compression is necessary)...Brian, you are describing two distinct artifacts which sometimes have a similar cause.

The busy, grainy areas seen in dark and pastel patches is quantization noise error, sometimes referred to as "contouring". It is a function of compression, and is created during the digitization process, primarily. But as you say, further manipulation by DTV can make it more noticeable.

The blocky breakup known as macroblocking where parts of the screen refresh late happens directly in the decoder in your DVR or TV tuner. It is a manifestation of the decoder not getting enough uncorrupted bits to properly recreate the picture. For that reason it can be a reception issue, which means better reception can fix it. It can also be due to overcompression, something that TV stations and DBS vendors alike can be responsible for, and in that case is not something that can be fixed at the receiver end.

If you compare DTV and DISH signals directly, you can see that DISH has a bit more quantization noise error than DTV, but then DTV has a bit more mosquito noise than DISH. The levels of the different artifacts are wholly dependent on the techniques chosen by the original encoding engineers and further manipulation done by broadcast outlets and other vendors. There are ways to balance them off against one another, and arbitrary choices are made regularly regarding which mix is best.

One problem MPEG-4 delivery has is that DTV must decode MPEG-2 and re-encode as MPEG-4. It is impossible to maintain the same level of artifacting when chaining dissimilar encoding algorithms, but DTV has been able to at least approach the original MPEG-2 quality.

[TomCat]

...I will utilize the AM21 to alleviate the problem. I look forward to seeing if it makes a difference this week for you, it should because the Comcast Lost (same WJLA)broadcast was flawless. An interesting note is that Lost is one of the few dramas that is shot in 720p which uses less bandwith than 1080i. If the 720p show is struggling, what does that tell you about everything else?720p takes about 7/8ths the bandwidth of 1080i for equivalent lack of artifacting, but that is typically not a factor at all when speaking about local HD channels, which are set up by local engineering at their own whim. Stations each have about 18 Mb/s to play with, and some take all of that for the main HD stream, while others may devote as little as 10 Mb/s to it. Whether the source is 720 or 1080 rarely if ever plays into that equation. What impacts DTV is how bit-heavy that encoded signal is and how much they feel they have to shave off of it to make it fit their infrastructure, and original format (720/1080) does not then really impact their system at all.

So, DTV receives OTA streams of all sizes and quality levels, and in nearly every case the compression at that point is mild enough to not really show much artifacting at all. With certain restrictions, DTV is allowed to downrez and bandwidth limit these signals on a case-by-case basis, and the severity of the original compression (or ironically enough, lack of same) can impact the secondary compression.

IOW, more simply put, there can be some solutions for MPEG-4 locals that work exceptionally well (I have seen no degradation vs. OTA in my market) and then maybe solutions for other particular channels that don't. Usually, if the original compression is done efficiently and artfully, DTV has more opportunity to further manipulate it without consequence than they do when the station either severely compresses it to the point of artifacting or just lets it all hang out at 18 Mb/s, making DTV approach a channel like that with a much bigger butcher knife.

Regardless, it is not really a 720/1080 issue at all. The bottom line is that DTV using MPEG-4 can never better or even match OTA, but typically they have been able to come very close. Impressively so. Just not for every channel, or for every program. The reasons are many, but 720/1080 isn't usually one of them.

We also have to consider the original content. One recent glaring example is "Canterbury's Law" (gone by next week). That is shot and produced so technically poorly that there is what appears to be a lot of video noise and grain, and general softness to the video. I think it might be shot on 16mm, which isn't really the best solution for HD. Adjacent shows on FOX typically look much better. The worse the original is, the exponentially-worse it looks when there is recompression and bit-limiting impressed upon it on its way to us through the DTV sats.

[Slip Jigs]

We also have to consider the original content. One recent glaring example is "Canterbury's Law" (gone by next week). That is shot and produced so technically poorly that there is what appears to be a lot of video noise and grain, and general softness to the video. I think it might be shot on 16mm, which isn't really the best solution for HD. Adjacent shows on FOX typically look much better. The worse the original is, the exponentially-worse it looks when there is recompression and bit-limiting impressed upon it on its way to us through the DTV sats.

TomCat - VERY informative. Where did you learn all that?

What shows do you think represent the best in HD and how do you think they're being shot? I'd like to see if your answer confirms what I think my eyes are telling me.