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jtown said:
Just to throw in my two cents, I watched four games yesterday. Two on FOX, one on CBS, one on NBC. NBC's looked like crap. No question. Fox had the best image quality (tho only 720, of course). CBS looked good in 1080 but was noticeably washed out. NBC just looked like crap. Lots of compression artifacts.

BTW, a high bitrate is not an absolute indication of high quality. It just means the potential is there. Crap in = crap out.
I watched one complete game on CBS (go Steelers!!!), most of one on Fox, bits and pieces of the 1:00 Fox game during sommercials with the Steelers game, and three quarters of the NBC game.

Much like you, the picture quality of the NBC game was by far the worst of the three for me. I preferred the picture of the CBS game the most, but that could be a number of factors, including the native resolution of my TV more closely matches 1080i than 720p. Regardless, the PQ on the Fox and the CBS games were head and shoulders above that of NBC, and bit rate doesn't have anything to do with it (as the bit rates for all three were similar). I agree with your statement - crap in --> crap out.
 

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Discussion Starter · #22 ·
I just sent an email to NBC Sports complaining about this, as it seems more and more like an issue on their end rather than only with the bitrate. Unfortunately, the email was bumped back saying it couldn't be delivered. No idea why, but I'll try again.
 

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mike_camden said:
Regardless, the PQ on the Fox and the CBS games were head and shoulders above that of NBC, and bit rate doesn't have anything to do with it (as the bit rates for all three were similar).
If the bit rate was similar on FOX and NBC, then that would be the reason quality was so bad.

High-definition 1080i video broadcasts require significantly more bandwidth to maintain a quality picture. A 720p60 football game will look great in 13-14Mbps from FOX, but will look horrific with less than 16Mbps from NBC.

I have seen the NBC source feed and it looks excellent. It is absolutely not a case of crap in, crap out.

Summary of Video Distribution at the Big Four
  1. FOX takes a 1Gbps (uncompressed) 720p feed at the truck, compresses it down to 73Mbps for the FOX operations center, which then compresses it down to a max of 14.6Mbps with industrial grade ($$$$) encoders. This signal is uplinked to satellite for affiliates.

    FOX affiliates pass this feed through without any extra processing or compression using specialized equipment provided by FOX corporate.
  2. CBS takes a 1.5Gbps (uncompressed) 1080i feed at the truck, compresses it down to 45Mbps for the CBS operations center, which then uplinks it to satellite at 45Mbps for distribution to affiliates.

    CBS affiliates process and re-compress this 45Mbps feed to 19.4Mbps or less. Some CBS affiliates have newer/better encoders than others. With CBS, a bitrate of ~12Mbps is typically required to produce a good 1080i picture on film-sourced series content, while a bitrate of >16Mbps is required to produce a good picture on high-definition 1080i video with movement, like football.
  3. ABC takes a 1Gbps (uncompressed) 720p feed at the truck, compresses it down to 45Mbps for the ABC operations center, which then uplinks it to satellite at 45Mbps(?) for distribution to affiliates.

    ABC affiliates process and re-compress this 45Mbps feed to 19.4Mbps or less. Some ABC affiliates have newer/better encoders than others. With ABC, a bitrate of 9-10Mbps is typically required to produce a good 720p picture on film-sourced series content, while a bitrate of 13-14Mbps is required to produce a good picture on high-definition 720p video with movement, like football.
  4. NBC takes a 1.5Gbps (uncompressed) 1080i feed at the truck, compresses it down to ~38Mbps for the NBC operations center, which then recompresses and uplinks it to satellite at 24Mbps for distribution to affiliates.

    NBC affiliates process and re-compress this 24Mbps feed to 19.4Mbps or less. Some NBC affiliates have newer/better encoders than others, and since NBC was the first network to launch with high-def, a number of affiliates are still using outdated, early generation Harris MPEG-2 encoders.

    With NBC, a bitrate of ~13-14Mbps is typically required to produce a good picture on film-sourced series content, while a bitrate of 16-18Mbps is required to produce a good picture on high-definition video with movement, like football.
As a result, the NBC feed will never look as good as the other feeds with an equivalent level of compression. More bandwidth is required for NBC to produce a comparable picture to CBS.

If you've ever done any video or image compression, you know that you get better results when you start with a higher quality, less compressed source. The fewer the compression steps, the better the result. For example, you get a far better picture when compressing a 500Kb PNG to 50Kb JPEG than you get when compressing a 50Kb JPEG of the same image down to 30Kb. The same principle applies applies with high-definition signal distribution.
 

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Yet another reason to dislike NBC. :) To make matters worse: re-compressing an already compressed 20 Mbps feed down to 12 Mbps is going to yield far worse results than if they were compressing the original uncompressed HD signal down to 12 Mbps. Anytime you take a lossy compression format (MP3, MPEG2, etc) and re-compress it to another lossy format, even the same format, your quality suffers.

My brother was over at my house last night and we watched the Giants/Cowboys game. 56" 1080P Samsung DLP TV, Comcast HD cable. I don't watch a lot of sports, so I was kind of shocked to see just how awful the picture looked. My brother kept saying, "I don't see it." But when I paused the DVR during a camera pan, and all we could see was a low-res looking, blocky mess of a picture, he started seeing it too.

I have to say that although I enjoy my HDTV a lot, I'm consistently disappointed with the picture quality of some HD feeds. I don't yet have an HD-DVD or BluRay player, but I'm told that these will present, by far, the best looking HD pictures currently available.
 

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Discussion Starter · #25 ·
I just watched "The Office" on cable... my God, it looked horrible. I have watched it OTA before and never had any issues with the quality. This was a disaster. EVERY quick zoom or pan with the camera led to horrible artifacts. It looked like mosaic in some cases. 12.7 Mbps bitrate.

I will call TWC tomorrow and complain... not that it will help much. I emailed them before but didn't hear anything, I emailed NBC too but my email was returned.

Didn't end up ordering the antenna because of the convenience of cable... but "Heroes" will look like crap here too, and I really would like that to be in good quality.
 

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Discussion Starter · #26 ·
I was corresponding with the local NBC affiliate, and asked about this. Here's the reply:
We broadcast the HD signal straight out the receiver from NBC. Our encoder for the Mpeg stream is set for about 12 Mbps. We also have 4.2 and room for 4.3 in our stream hence the setting for about 12. Time Warner gets our signal over the air and I don't know what they do to it after that. They may compress it even more I'm not sure. I'll try to find out more. I watch us over the air at my house and I don't notice artifacts on a plazma screen with true HD programming. I do see artifacts on non-HD material.
12 MBps seems really low for OTA, even if they do have one subchannel in use. I can't argue with him yet though, as I haven't seen the OTA broadcast here...
Would TWC be doing something else with the signal that could cause the problems? Maybe something like constant bitrate versus variable bit rate (not sure if that is relevant here)?
 

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I was corresponding with the local NBC affiliate, and asked about this. Here's the reply:

12 MBps seems really low for OTA, even if they do have one subchannel in use. I can't argue with him yet though, as I haven't seen the OTA broadcast here...
Would TWC be doing something else with the signal that could cause the problems? Maybe something like constant bitrate versus variable bit rate (not sure if that is relevant here)?
He told you that their station encoder is set to 12Mbps. That is barely adequate for series programming, and completely inadequate for 1080i video like sports.

As I noted in my previous post, the NBC network feed sent to every affiliate is about 24Mbps. At least 16Mbps is needed to produce an acceptable picture on most NBC sports broadcasts, and 17+Mbps is preferred. At 12Mbps, 1080i sports will look like garbage.
 

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Discussion Starter · #28 ·
He told you that their station encoder is set to 12Mbps. That is barely adequate for series programming, and completely inadequate for 1080i video like sports.

As I noted in my previous post, the NBC network feed sent to every affiliate is about 24Mbps. At least 16Mbps is needed to produce an acceptable picture on most NBC sports broadcasts, and 17+Mbps is preferred. At 12Mbps, 1080i sports will look like garbage.
Do you think there's any "higher up" I could contact here? Does NBC have some guidelines for their stations? I find it odd that the Tucson, AZ station had a ~17Mps bitrate and the San Antonio, TX station has such a low bitrate. Looks like I can't blame this on the cable company after all.
 

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He told you that their station encoder is set to 12Mbps. That is barely adequate for series programming, and completely inadequate for 1080i video like sports.

As I noted in my previous post, the NBC network feed sent to every affiliate is about 24Mbps. At least 16Mbps is needed to produce an acceptable picture on most NBC sports broadcasts, and 17+Mbps is preferred. At 12Mbps, 1080i sports will look like garbage.
I agree with those figures. BTW the 12mbps translates to just about 5.5GB/hr for those checking their disk usage on their one hour recordings to see what they are getting.

I happen to be getting UHD (1080i) at 4.35GB and y'all can do that math. :eek:

My NBC is also pretty low (haven't looked lately) with CBS being about 10% higher. I was pleasantly surprised when ESPN (720p) went to 7+GB/hr around week 5 on Monday Night Football and then stayed in the upper 6's the rest of the season.
 

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Micke,

TWC is NOT compressing your signal whatsoever. San Antonio will only put 2 HD channels in a QAM. This is totally NBC's fault. The only HD channels that are messed with in any way are HD channels that are SDV, and only then they are clamped so as not to exceed a certain bandwidth. Of course, if it's SDV your tivo can't get it so why be concerned about those.
 

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Discussion Starter · #31 ·
Thanks for that information.

I guess I will respond and ask why they have the encoder set to such a low bitrate (although I can guess the answer). I wonder if the guy is not watching at the right distance. I view at just over the SMPTE recommended distance for HD (about 6 feet for my 42" screen) to take advantage of the full resolution, which is closer than most people. Obviously, these defects are a lot easier to spot then, but on most material this issue is nonexistent.
 

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Thanks for that information.

I guess I will respond and ask why they have the encoder set to such a low bitrate (although I can guess the answer). I wonder if the guy is not watching at the right distance. I view at just over the SMPTE recommended distance for HD (about 6 feet for my 42" screen) to take advantage of the full resolution, which is closer than most people.
Unfortunately, most broadcast stations still use small screens (typically under 20") to monitor their signals.

If you are able to talk to the engineer on the phone, you might invite him (and the station manager) to visit your house to see the quality of their high-definition sports broadcast on a larger screen.
 

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Discussion Starter · #33 ·
Unfortunately, most broadcast stations still use small screens (typically under 20") to monitor their signals.

If you are able to talk to the engineer on the phone, you might invite him (and the station manager) to visit your house to see the quality of their high-definition sports broadcast on a larger screen.
He says in the email that he watches it at his house on a "plazma" (sic) screen, so I assume he's got the right size. I also assume that he sits too far away to notice this at the level that I do. If I sit 15 feet away, this is much less noticeable (of course). I wonder if taking a snippet of it and showing him (I have it on the PC in uncompressed form) would do any good.

OT: I honestly don't understand why some people even have HD, they sit so far away from their screens that the improvement in resolution is almost negligible.
 

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What is the problem with HBO HD? Movies look like crap -- artifacts, blurred motion, pixelization. I was so pysched to get a larger hard drive and start recording movies, but they look awful. Much worse that standard DVD.
 

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What is the problem with HBO HD? Movies look like crap -- artifacts, blurred motion, pixelization. I was so pysched to get a larger hard drive and start recording movies, but they look awful. Much worse that standard DVD.
Who is your provider? Sounds like they are degrading the quality of that channel.
 

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I hate to say this, but I've noticed the same thing since getting my S3.

I was using an SA 8300HD prior to the S3. While I hated the SA box's interface, my recollection is that the picture quality is somewhat better with HD programming, ESPECIALLY at times of rapid motion.

On the other hand, my S2 replaces a ReplayTV 5504. The S2's image quality at "high" or "best" settings is slightly better than that of the ReplayTV at it's "high" setting.

Does anyone here have a similar experience in comparing a cable company DVR to the S3?
 

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Discussion Starter · #37 ·
I hate to say this, but I've noticed the same thing since getting my S3.

I was using an SA 8300HD prior to the S3. While I hated the SA box's interface, my recollection is that the picture quality is somewhat better with HD programming, ESPECIALLY at times of rapid motion.

On the other hand, my S2 replaces a ReplayTV 5504. The S2's image quality at "high" or "best" settings is slightly better than that of the ReplayTV at it's "high" setting.

Does anyone here have a similar experience in comparing a cable company DVR to the S3?
At my previous house I had a different cable provider, but I noticed no difference when going from the SA 8300HD to the Series 3. I also have no other issues with motion other than on my local NBC affiliate (HDNet Movies for example, which I believe is also 1080i, looks great).
 

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I hate to say this, but I've noticed the same thing since getting my S3.

I was using an SA 8300HD prior to the S3. While I hated the SA box's interface, my recollection is that the picture quality is somewhat better with HD programming, ESPECIALLY at times of rapid motion.
Picture quality is as good as my Motorola DVR in fixed mode, and better in native mode.

Fixed 720p mode will degrade resolution on 1080i channels (effectively downconverting them to 540p), while fixed 1080i mode will degrade motion on 720p60 channels.

Some providers recently increased their compression levels to make room for new HD channels.
 

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I experienced the blocking as well, with FIOS, and I think cable before that. Interesting thing is, this blocking is obvious on a 47" LCD 1080P, but barely visible on a rear-projection CRT 1080i (not calibrated) - both using TiVo HDs. It is there on the CRT, because I can see it if I pause. I don't have a plasma to sample, so I don't know if they might minimize the blocking as well.
 
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