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There Really Aren’t Any HDTV Standards
Should there be?
by KathrynV 01:19PM Sunday Jul 27 2008
Back in the late 1980’s the Advanced Television Advisory Committee was formed with the purpose of creating a set of standards for HDTV. A report exploring HDTV quality says that the efforts of the ATC had minimal impact and suggests that there really are no HDTV standards. The report notes that there are requirements regarding the number of pixels a signal must have but says that there is no rule about the quality of those pixels. More importantly, it notes the fact that HDTV requires a high bit rate when uncompressed and therefore is typically compressed to some degree which compromises picture quality.
quote:
"Surprisingly, there is little regulatory control over compression. According to ATSC president Mark Richer, the ATSC standard does not require minimum bit rates for over-the-air broadcasters, and the FCC requires only that broadcasters provide at least one service that is equivalent to analog television."
Satellite and cable companies have been challenged about the compression issue with customers and are working to make changes but the suggestion is that there should be some better standards put into place for HDTV today.

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KrK
Heavy Artillery For The Little Guy
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Tulsa, OK

Our way or the highway

The reason why these standards are so hard to get defined and in place is because the various equipment manufacturers patent everything and then try and get the standard defined as to something they own patents over--- IE they try to basically own the market before it even exists.

This is why these standards often takes years and years and years of squabbling and protracted "discussions" and so on and so forth and little often gets done.

The only way to get a standard quickly adopted methinks is if it was royalty free--- ie manufacturers, broadcasters, etc etc couldn't be hit up for money for going with a standard. Problem is I doubt any of the interests involved want to give up THEIR patents or IP on these issues...

... and so thus, there we are.
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Da Man

join:2008-05-08
Hanover, PA

Re: Our way or the highway

Because requiring 18Mbps for 1080i to qualify as HD is patentable.

james1

join:2001-02-26

Re: Our way or the highway

He made a good point, you on the other hand are just being a smart ass. Perhaps 18Mbps being required for 1080i would cause a company who has been working on a superior compression technique to not support the new standard? Perhaps the new standard that is being negotiated would define MORE than how much bandwidth is to be used for a given resolution.

MxxCon

join:1999-11-19
Brooklyn, NY
18Mbps for 1080i != quality

The problem with such rule is there is no standard measurable unit of image "quality".

bitrate means nothing if codec doesn't know how to properly utilize it. while at the same time quality codec can encode superior image at smaller bitrate.

Just look at "megapixels" in digital cameras.

sporkme
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Re: Our way or the highway

said by MxxCon:

The problem with such rule is there is no standard measurable unit of image "quality".
There certainly good be though. Take the original, zoom in to some number of pixels. Do the same on the compressed version. Count how many pixels are different.

You can do this experiment at home. Take a high quality jpg. Save it with really crappy compression settings. Open up both. Zoom in to a complex area of the image. Count the pixels that are different.
EPS4

join:2008-02-13
Hingham, MA

Re: Our way or the highway

But what is "different"? If a shade of red is slightly changed, is that equal to the shade of red getting blurred into gray?

MxxCon

join:1999-11-19
Brooklyn, NY
said by sporkme:

Take the original, zoom in to some number of pixels. Do the same on the compressed version. Count how many pixels are different.

You can do this experiment at home. Take a high quality jpg. Save it with really crappy compression settings. Open up both. Zoom in to a complex area of the image. Count the pixels that are different.
that kind of testing goes exactly against the way lossy video and audio compression works.

you try to throw away as much data as possible while trying to keep it perceptually identical TO HUMANS.
so at which point will you consider 2 pixels different? how would you know if some different pixels are important in an image or not?
would you want to waste video bandwidth trying to preserve details of a perfectly black sky with a few pixels being one shade brighter? or would you rather use it somewhere more obvious?

Dogfather
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Re: Our way or the highway

That is part of what a standard would determine...at what point are they considered different.
PDXPLT

join:2003-12-04
Banks, OR

1 edit
said by MxxCon:

The problem with such rule is there is no standard measurable unit of image "quality"
Not true.

There are ITU and MPEG standards for making objective measurements that correlate to perceived image quality.

And as for other "HDTV standards", there are whole volumes of ATSC and MPEG standards for modulation, coding, and transmission of HDTV signals.

The title of this article is the problem. There are plenty of HDTV standards, including those for objective quality measurement.

What there aren't any of are HDTV quality regulations. There's no law that that states what image quality providers must broadbast, other than an ambiguous one that says at least one prgram equivalent to NTSC quality must be provided.

Broadcasters, cable MSO's, and DBS providers believe most consumers don't know and don't care about pciture quality. They're probably right; how many TV's are horribly misadjusted? Most of them. The providers believe they'll be more profitable providing quantity over quality. So they pack in as many overcompressed channels as they can.

The one place you may get relief from this is Blu-Ray. There is no economic incentive to compress more than what is necessary to fit on the disk. And the folks controlling the compression are the same who produced the film, and have an interest in having its quality preserved and displayed.

MxxCon

join:1999-11-19
Brooklyn, NY

Re: Our way or the highway

said by PDXPLT:

There are ITU and MPEG standards for making objective measurements that correlate to perceived image quality.
show me
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Dogfather
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3 edits

Re: Our way or the highway

ITU-R BT.500
»www.dii.unisi.it/~menegaz/Doctor···0-11.pdf

My guess is that the MPEG group would follow this recommended methodology as other engineers and researchers would.
ricep5
Premium
join:2000-08-07
Jacksonville, FL
ATSC was actually moving along quite well until Microsoft stuck their nose in it (late) and starting pushing 720p with ABC in tow.

It was really simple, 480p for NTSC upconversion and 1080i for the higher def programming.

Then MS pushed this "must be seen on a computer" mentality and it really went bonkers after that. The arguments ended up getting irrational so ATSC just said "any resolution is acceptable" which turned it into the wild west.

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Re: Our way or the highway

said by ricep5:

It was really simple, 480p for NTSC upconversion and 1080i for the higher def programming.
I assume you are aware there are a number of significant shortcomings to using Interlace as opposed to progressive scanning.

NTSC is not progressive it is interlace to address 1930's vintage technology.

/tom
ricep5
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Re: Our way or the highway

I am well aware of the benefits of progressive over interlacing. I was merely stating when things got hairy on the ATSC.

There were other agendas in play other than the progressive stuff, sub-channeling rights, cost of conversions, bandwidth issues, technical issues with 8VSB.

It's a miracle the thing got off the ground at all.

In all, technology advances overcame most of the political agendas. It has become extremely flexible in some areas and has left alot to creativity. We won't recognize it 20 years from now from what we have today.

Argggghhhhh

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What? No Standards?


I don't think there's an ATSC quality standard for the same reason that there's never been a standard for picture quality with NTSC. If a station didn't want to spend the money for a high quality transmission plant, then they suffered picture quality and they do so at their own peril. Who wants to watch a program where the detail sucks or the there's color shifts? If ATSC stations choose to have an "HD" channel running at 9 megabits and a flock of 1 megabit 480i sub-channels, they do so at their own peril.

This move to digital was never about the consumer, for if it was NTSC would run in parallel with ATSC until the last NTSC tube blew its filaments and was laid to rest. Instead, this is about a frequency grab and it is being paid for by television broadcasters who have to shell out millions of dollars for a new plant at a time when viewer counts are hitting the skids and consumers who have to spend anywhere from $50 to thousands in order to replace what has been working fine for years and years.

This time next year, there will still be people who are sitting in their living rooms wondering what the hell happened to their over-the-air broadcasts.
PDXPLT

join:2003-12-04
Banks, OR

Re: What? No Standards?

said by Argggghhhhh :


I don't think there's an ATSC quality standard for the same reason that there's never been a standard for picture quality with NTSC.
Heh, heh. You must be alot younger than I am. At one time there was indeed enforced quality regulations for NTSC signals, enforced by the FCC. They were done away with in the 1970's, except for those related to potential interference with other broadbast stations, and replaced with a more "market-based" approach.

nightdesigns
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How many times is this signal recompressed???

Let's take your typical major league sports event. The picture quality is only in it's purest form in the production truck. Once it leaves that, it is recompressed as it is sent via satellite or fiber to the main channel HQ. From there, it is once again recompressed to be passed through the channel's Master Control. From there, it is once again recompressed as it is sent back to satellite for the local affiliates to pick up and to transmit. Once again, it's recompressed through their master control, then recompressed for transmission to you. If your have cable, your cable provider picks up that signal, recompresses it to their standard, then compresses it once again to fit down the bandwith pipe with all of your other signals.

In Some situations, a full analog, uncompressed channel TV can look better than HDTV. Those are few and far between and starting next year, non existent.
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mgraves1
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Re: How many times is this signal recompressed???

The existing standards specify only valid frame sizes, frame rates and compression schemes. There's nothing in the standard about compression ratios. Thus there can be a lot of variation in perceived image quality.

In practice what you receive from a broadcaster (ie, off-air) is going to be very good. What you receive from a cable or satellite provider will likely be not as good.

It is true that an HD signal may be decompressed and again compressed in the transmission process. When care is taken in these steps the loss of perceived image quality need not be dramatic.

Within a TV station the compression for transmission actually occurs after the master control suite, usually just before the link to the transmitter. They generally need to get all their production work done before the ATSC encoder. That means all insertion of branding graphics, time & temp for news, weather warnings, EAS advisories, etc.

With cable and satellite providers the picture is completely different. They receive the signals somehow, then frequently transcode them to a different bit rate for delivery. They may also transcode from MPEG-2 to H.264/MPEG-4. Reducing the bit-rate consumed per channel is how they aim to offer a zillion channels without scaling their transmission system at incredible expense.

Some content providers (Disney, ESPN, etc) have specific terms in their contracts that stop the carriers from bit rate reduction. They do this to ensure the final quality of their delivered product. Smaller content providers have little or no leverage to make such demands.
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iansltx

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Re: How many times is this signal recompressed???

How about a standard that defines HD as "quality of or equivalent to X megabits/second using X compession scheme at 720p, X megabits at the same compression scheme for 1080i" etc. It's more of a benchmark than a standard but once it's set there's at least a reference to compare codecs, delivery methods, etc. to.

tschmidt
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Re: How many times is this signal recompressed???

said by iansltx:

How about a standard that defines HD as "quality of or equivalent to X megabits/second using X compession scheme at 720p, X megabits at the same compression scheme for 1080i" etc.
The problem with that notion is compression is both spacial and temporal.

Compression algorithm works on image it is presented. Nothing in either the ATSC or NTSC define image quality other then in terms of what can be reproduced.

To develop a reasonable end user image quality specification it would have to include both image itself and how it changed over the duration of the test. Would also have to make statistical allowance for uncorrectable transmission errors.

As others have said ATSC is a transmission specification as is NTSC. Goal of the spec is to define both transmission and rendering characteristics for broadcasters.

/tom

Vchat20
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Re: How many times is this signal recompressed???

Agreed. Not only that, but if they DID implement such a 'restriction', it would start wasting bandwidth where it shouldn't have been wasted in the first place. All these weather subchannels each station is so interested in are a very good example. Put a limit of, say, 2mbit on a (mostly) slideshow-esque 480i broadcast and you have went right over the point where the PQ improvement with increased bandwidth have levelled off. And this wouldn't take into account for VBR encoding for these channels which can vary wildly depending on content.
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uid1307457
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Tempe, AZ
said by mgraves1:

Some content providers (Disney, ESPN, etc) have specific terms in their contracts that stop the carriers from bit rate reduction.
Discovery HD channels are one of those that have a contract to stop bit rate reduction. Ever notice how Discovery HD always looks a tad better than other HD channels?

dvd536
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Re: How many times is this signal recompressed???

said by uid1307457:

said by mgraves1:

Some content providers (Disney, ESPN, etc) have specific terms in their contracts that stop the carriers from bit rate reduction.
Discovery HD channels are one of those that have a contract to stop bit rate reduction. Ever notice how Discovery HD always looks a tad better than other HD channels?
you mean the 'zoom - o - vision - hd lite esque discovery channel?'
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clickie8

join:2005-05-22
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Eventually stations will have to move to stream splicing to get around the successive encoding passes.

mgraves1
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Re: How many times is this signal recompressed???

A certain amount of that happens now, but the hardware systems that do it are still expensive and limited in their capabilities.

The current generation of splicers can insert a static logo or switch between sources but not much more. Certainly when we see them try to implement an EAS warning crawl the font that they produce looks pretty bad.

There's another things to be aware of about the compression. The ATSC standards are all based upon MPEG-2 which is getting quite old by now. H.264/MPEG-4 can produce the same perceived image quality at about half the bit-rate. This is one of the reasons that cable and satellite providers, as well as streaming online sources, prefer H.264 for HD video.

Consider that an off-air stream can be as much as 19.2 mbps MPEG-2, although that can be split across several program streams. Apple TV has an internal hardware limit of 8 mpbs. By encoding H.264 and only 720p Apple TV maximizes their image quality for a given amount of bandwidth. It's the lowest spec real HD that they can reliably delivery based upon modest hardware.

Compare that to HD-DVD or Blu-Ray which can deliver over 30 mpbs MPEG-2, H.264 or other codecs.

Downloading or streaming certainly is convenient. Off-air just simply looks better. But HD optical media will deliver the best picture every time.
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djrobx
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quote:
In Some situations, a full analog, uncompressed channel TV can look better than HDTV. Those are few and far between and starting next year, non existent.
Maybe for some brief, fleeting moments of extremely high, random motion. The other 99.9% of the time, the HD picture will smoke the SD one. No matter how artifact-free the SD picture is, the detail needed for large TV sets will never be there.

I have to admit, I'm pretty impressed by what H.264 is able to do with a HD signal. I'm giving U-verse a try, and they compresses HD all the way down to 5.5mbps. While the result is decidedly "HD lite", it's not nearly the disaster I thought it'd be. It seems MPEG-4 artifacting is a lot more natural than the blocky mess MPEG-2 becomes when bit starved.

A900MHz Fan

join:2004-07-12
Mitchell, SD

1 edit
said by nightdesigns:

Let's take your typical major league sports event. The picture quality is only in it's purest form in the production truck. Once it leaves that, it is recompressed as it is sent via satellite or fiber to the main channel HQ. From there, it is once again recompressed to be passed through the channel's Master Control. From there, it is once again recompressed as it is sent back to satellite for the local affiliates to pick up and to transmit. Once again, it's recompressed through their master control, then recompressed for transmission to you. If your have cable, your cable provider picks up that signal, recompresses it to their standard, then compresses it once again to fit down the bandwith pipe with all of your other signals.

In Some situations, a full analog, uncompressed channel TV can look better than HDTV. Those are few and far between and starting next year, non existent.
said by nightdesigns:

Let's take your typical major league sports event. The picture quality is only in it's purest form in the production truck. Once it leaves that, it is recompressed as it is sent via satellite or fiber to the main channel HQ. From there, it is once again recompressed to be passed through the channel's Master Control. From there, it is once again recompressed as it is sent back to satellite for the local affiliates to pick up and to transmit. Once again, it's recompressed through their master control, then recompressed for transmission to you. If your have cable, your cable provider picks up that signal, recompresses it to their standard, then compresses it once again to fit down the bandwith pipe with all of your other signals.

In Some situations, a full analog, uncompressed channel TV can look better than HDTV. Those are few and far between and starting next year, non existent.
Signals from ESPN to resale providers is not compressed below 40.461Mbps, Fox is not below 64Mbs.

Also, MPEG4 and H2.64 start to lose the advantage in quality over MPEG2 in the 12-15Mbps area.

Neal

mgraves1
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Houston, TX
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Percieved image quality

The really big problem is that you can't regulate something that's based upon perceptual data. Bit-rates, codecs, signal paths & recording schemes all come into play. Some stages are more transparent than others.

You can't really even say that zyx is the equivalent to abc because the failure modes of the compression schemes may reflect different artifacts. In MPEG you get DCT blocks and twittery edge artifacts...in H.264 something different...in JPEG2000 something different again.

I have heard it said by someone I respect as knowledgeable in the area, that 8-9 mbps H.264 looks every bit as good as 16 mbps MPEG-2. The latter being a sort of best case off-air where a broadcaster has one primary HD stream and one secondary SD stream.
--
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»blog.mgraves.org

Katzendreck

join:2003-09-29
Calgary, AB

Not terribly concerned

.. about widespread HDTV, especially compared to the lack of choice in content in terms of the crap people pay for just to get service. Once consumers get a la carte, then we can explore the standards of HDTV. Until then, no cable/satellite television gets any money from me, regardless of how crisply defined it is.
EPS4

join:2008-02-13
Hingham, MA

Re: Not terribly concerned

There's a such thing as OTA HDTV, though... (which is one of the major things the ATSC is concerned about)

RR Conductor
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1 edit
said by Katzendreck:

.. about widespread HDTV, especially compared to the lack of choice in content in terms of the crap people pay for just to get service. Once consumers get a la carte, then we can explore the standards of HDTV. Until then, no cable/satellite television gets any money from me, regardless of how crisply defined it is.
I'm against A La Carte, many good, but lesser watched channels (like RFD TV »www.rfdtv.com/ ) could be gone without the money coming in from the other channels. I don't mind paying a little more if it means I get a choice of channels, and the channels I watch will be there tomorrow.
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Vchat20
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Plain and simple:

HDTV has plenty of standards, both QAM and ATSC. You can't broadcast any random resolution, only 720x480i/p,1280x720p,1920x1080i, and, if future compression techniques improve, 1920x1080p. Only mpeg based video and audio codecs can be used (though existing equipment has dictated mpeg2/ac3 only for compatibility. Again, the future may open up to allow mpeg4 over QAM/ATSC). bandwidth limits per 'channel' are set (19.2mbps for each 6mhz band ATSC, 38mbps per docsis 1.x/2.x @ 256-QAM, ~30mbps for 64-QAM) so the limit of what you can reliably cram in is set. I could go on.
Same could be said for NTSC's heyday. You had a set limit of what resolution you could broadcast out on your limited 6mhz channel: 480i. Audio was restricted to FM modulation for stereo broadcasts. You were locked into a single 6mhz channel just like now. Again, I could go on and on...

Like others have said here already: What people are crying about being 'no standards' is the perceivable picture/audio quality with these new digital tv broadcasting systems. Between of not only having High def sets and just overall better quality sets even in 480i CRT models; All in comparison to what we had gotten used to since NTSC's initial inception with the relatively inferior quality sets and the natural aptitude to have SOME form of interference and loss of picture both on OTA and Cable transmission. There was little room for complaints unless you got a better antenna or bought a higher quality tv. We have all just gotten used to the SUBSIANTIALLY increased quality now.

But like has been stated: There is no standard for actual picture/audio quality set and it would be near impossible to set a standard here as it has way too many factors involved, not one of which is the content itself which CONSTANTLY changes.

Granted, I'd personally like to see a regulation placed on cable companies that says something akin to 'no more than 3 HD channels per QAM on their own', etc.. But it would just be way too much hassle to regulate. Things are already slowly moving to mpeg4 which drastically changes the ballgame in bandwidth utilization, and who knows what new mpeg based codec may pop up in the near future.
--
I swear, some people should have pace-makers installed to free up the resources. Breathing and heart beat taxes their whole system, all of their brain cells wasted on life support.-two bit brains, and the second bit is wasted on parity! ~head_spaz
DeFlanko

join:2007-02-05
San Pedro, CA

Re: Plain and simple

ok first time poster, very young buck here... Mid twenties..

now from my stand point i can understand the no standard via book standard..

but there appears to be a General standard... 480p 480i 720p 72i 1080p 1080i these are all HD signals...

now how it comes to us its a complete different story..

which signal do i like better atm.. off air Los Angeles HD..

i think its the CLEANEST signal, no bullshit, to your hdtv.

here in LA i think we have like 30 stations already.

next up id have to say DirecTV.

Then any cable company that can produce a HD signal.