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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Jan 29, 2008 9:55 pm Post subject: |
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| WTS wrote: | | Does DIsh do the same downrezzing? |
Yes. I believe there were a few stations Dish did not used to down rez, but I think they now downrez all 1080i signals to a 1280 horizontal resolution.
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Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Jan 29, 2008 10:12 pm Post subject: |
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| ecrabb wrote: | One other thing to consider that everybody always glosses over when they tear into DirecTV for reduced spatial resolution: Resolution isn't the whole story! Resolution, data rate, picture content and processing all play together to create the end result. It's entirely possible that a 1920x1080i stream at 12Mbps could look SOFTER than a 1280x1080i stream at 12Mbps. It depends on how it was processed. Read on...
One 'advantage' to DirecTV's down-sampled 1280x1080i "HD Lite" is that it uses about 2/3 the transmission bandwidth that a full 1920x1080i signal does. That also means that at comparable date rates, the "HD Lite" signal is about 33% less compressed. This isn't trivial.
If you've watched much DirecTV vs. OTA 1080i MPEG-2, you may have noticed that there is typically a lot more motion-induced macroblocking in the OTA stream compared to most DirecTV material. That's because while the OTA stream may be running at 15 Mbps, the DirecTV at 12Mpbs is actually less compressed than the OTA stream is. The OTA encoder saturates much more quickly with high motion than does the 'HD Lite' stream.
Now, in general, I'm sure the data rate is a little higher on Fios than it is on DirecTV, but is it always 50% higher? I don't know. I do know that a 50% higher data rate is what it would take to compress the data stream no more than the equivalent "HD Lite" stream.
Now... Processing. One way to decrease compressed data rate and increase codec efficiency is by pre-filtering. If you reduce high-frequency (high resolution) content some by softening, blurring, averaging, etc. you'll get the same apparent visual quality in a much smaller data stream with fewer visual compression artifacts. It could be that some of the Fios material - while it is 'full' spacial resolution - it may be pre-filtered to increase compression efficiency and reduce transmission bandwidth, and end up not looking that much better than the comparable DirecTV signal. From what I've heard, that's not generally the case, but I just wanted to throw out there that digital compression and transmission isn't as simple as comparing spatial resolution and data rate only.
SC |
What you say is true. But your assumption is wrong. Verizon sends out exactly what they get from the provider. Every single provider gets the exact same stream from the source. They can do nothing to make that signal better, only things to make it worse. In fact, there are logically 4 things they can do with it:
1) Send it back out "as-is" with no additional processing.
2) Pre-filter and recompress
3) Down rez it.
4) Introduce a higher level of compression
5) Any combination of 2-4.
Verizon FiOS does number 1. Comcast, Dish, and DirecTV all do number 3 and 4 to my knowledge.
Also, there is nothing you can do to get rid of compression artifacts from the provider. If the compression introduced macroblocking, then not softening or whatever will get rid of it. You'll just get softer macroblocking.
Your argument makes the most sense if the providers all got a raw signal or an even higher bit rate signal and all had to decide how to make it fit into 19.2 or less. But they don't. They all get the same MPEG2 compressed signal from the source. So downrezzing it can never result in a better signal than sending it out as-is. Thus, until Comcast, Dish, and DirecTV start sending it out as-is (or doing nothing more than a straight lossless conversion of MPEG2->MPEG4) their signal can not possibly be as good as Verizon's.
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Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Jan 29, 2008 10:16 pm Post subject: |
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One other thought, if the sony actually has a better DAC than the Fury, you would see this. To make all things equal, you could test them both with the HDMI out to the Fury.
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Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Tue Jan 29, 2008 10:54 pm Post subject: |
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Dave, how did you come by the notion that Verizon 'sends it out as is' and it's only everybody else that re-compresses? Do you think Discovery HD Theater, Showtime HD, etc. ORIGINATES at the measly 15-20 Mbps you see at your house from the provider? That's the customer delivery data rate, not the head-end transport data rate!
From everything I've ever read on the subject, the customer delivery providers (Verizon, DirecTV, Dish, etc.) all get the same high-quality feeds from their respective head-ends (whether it's Showtime, Discovery, etc.) at somewhere close to 40 Mbps, and then do whatever they need to do with it to fit their system's bandwidth profiles and their contractual agreements. Sometimes that's reformatting and scaling (DirecTV) or just re-compression.
Verizon is shaping their bandwidth just like everybody else. They just don't have to do it as much because their delivery network (fiber) isn't as bandwidth-constrained as the coax or satellite providers' systems.
SC
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Jan 29, 2008 11:18 pm Post subject: |
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| ecrabb wrote: |
From everything I've ever read on the subject, the customer delivery providers (Verizon, DirecTV, Dish, etc.) all get the same high-quality feeds from their respective head-ends (whether it's Showtime, Discovery, etc.) at somewhere close to 40 Mbps |
Where did you read this, as it is counter to everything I've read? If this were true, TNT HD would not look like sh!t on every single provider since at least one provider would not compress it down to the low bit rate.
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Dave
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Tue Jan 29, 2008 11:26 pm Post subject: |
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I didn't say every content provider was offering up a super-high-quality stream. Obviously, if TNT wants to send a sh*tty stream, they can do so. They can also use older movies, lower-quality masters to encode from, crappy encoding equipment, and low-paid monkeys to operate it. That's all separate from what I'm saying, though.
The premium providers like Showtime, HBO, Discovery HD Theater, etc. are all originating a much higher higher-quality stream than what you see at your house (whether Verizon or not). Verizon just steps on it a lot less than most of the other providers - because they don't have to.
SC
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WanMan
Joined: 19 Mar 2006
Posts: 10270
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| Posted: Wed Jan 30, 2008 12:05 am Post subject: |
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| Person99 wrote: | | stefuel wrote: |
I know you'll think I'm crazy but after numerous A/B's, I still think DTV is a sharper image. Not by much but noticable. |
OK, I know you are going to think of this as picking on the Ampro, but I'm not--that much. 
DirecTV downrezzes signals from 1920x1080i to 1280x1080i. FiOS does not. So, if your PJ cannot resolve the 1920, it is going to look a little less sharp. As a test, you could hook up a good scaler like a lumagen and downrez the FiOS signal to 1280x1080i and see if it looks sharper than the DirecTV. |
Has this been proven the case for the MPEG-4 distribution?
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Wed Jan 30, 2008 12:14 am Post subject: |
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I haven't heard anything or seen any comparisons to verify one way or another since the MPEG-4 rollout.
Of course, all my info about data rate only applies to MPEG-2. A 1080i MPEG-4 stream at 10 Mbps will probably look better than an MPEG-2 stream at 20 Mbps.
SC
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Fri Feb 01, 2008 10:28 am Post subject: |
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I also think the color is not as saturated with Fios as with Directv. Not sure if it's a stb issue or source issue. I had hoped to get Heywood J over to see the A/B but the wife cancelled the Directv subscription last night. I'm going to set the dvr to record test patterns from HD NET and try a color calibration next week.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Fri Feb 01, 2008 3:41 pm Post subject: |
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Chip,
Are you using HDMI or component on the Fios box (does it even have component)? There are a couple of threads (and one from Curt just yesterday) about some of the newer HDMI hardware having really pathetic component outputs, compared to older hardware.
SC
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Fri Feb 01, 2008 11:55 pm Post subject: |
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I am using the HDMI output into a HD Fury.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Sat Feb 02, 2008 6:27 am Post subject: |
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Oh, OK. Never mind, then. As you were.
SC
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sat Feb 02, 2008 11:53 am Post subject: |
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| Person99 wrote: | | One other thought, if the sony actually has a better DAC than the Fury, you would see this. To make all things equal, you could test them both with the HDMI out to the Fury. |
To late, the wife cancelled the DTV account. Not that it would have mattered as my sat hd200 is pre-HDMI and only has DVI for a digital connection.
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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ecrabb
Forum Moderator
Joined: 13 Mar 2006
Posts: 15909
Location: Utah
TV/Projector: JVC RS40, Epson 5010
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| Posted: Sat Feb 02, 2008 2:54 pm Post subject: |
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That would have been all the better, I think. In that case, the HD Fury still would have been doing the D/A conversion, it would have just been doing it without the rights-management handshaking stuff.
SC
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stefuel
Joined: 07 Mar 2006
Posts: 3353
Location: Green Harbor MA USA
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| Posted: Sun Feb 03, 2008 12:07 pm Post subject: |
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Oh well, by the time the contract runs out on this installation, we'll be into the mandate timeframe where everything should be HD. At that time, there should be more options available 
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Chip
A Barco is only a AmPro with training wheels
Card carrying member of the AVS chain gang.
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Person99
Joined: 09 Mar 2006
Posts: 4899
Location: Flower Mound, TX
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| Posted: Tue Feb 05, 2008 5:44 pm Post subject: |
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Well, since equal A/B tests were never done, I'm not sure where the problem is. I don't think the problem is FiOS based upon my experience.
My bet is it is one of the following:
1) The PJ resolves the 1280 signal of DirecTV better than the 1920 of FiOS, so it looks sharper.
2) The FiOS signal path is introducing the softness (either from the Fury, or something else).
3) The Fury DAC is inferior to the DirecTV box's DAC.
You can test 1 but using a computer source and projecting the same image at 1280x1080i and 1920x1080i and see if the 1280 looks sharper. If so, problem solved.
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Dave
A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station....
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