HDTV Over IP

gravelpup writes " NASA Watch has this article about a NASA demo of streaming an HDTV feed over a 20Mbps network from D.C. to California. Suddenly, watching NASA TV at home over a dinky DSL connection doesn't seem so cool anymore." For some reason this just makes streaming high quality video over the net seem even further away to me.

Comments

of bit rates and band widths

[foobar104]

Just a clarification.

When people say "HDTV," they can mean either the full-bandwidth uncompressed signal (on the order of 1.3 Gbps) or the broadcast-standard signal (MPEG-2 compressed to the order of 19.7 Mbit, or about 50-to-1, more or less).

Obviously this test didn't use uncompressed HDTV. Must have used MPEG-2.

When it comes to standard definition TV, the stuff you get over digital cable or DBS is typically between 4 and 6 Mbit. I think most people would consider 2 Mbit to be unacceptably noisy... but then again, I can ignore an awful lot of softness and artifacting from my TiVo, so maybe even 2 Mbit would be acceptable under the right circumstances.

Uncompressed standard-def TV, on the other hand, is carried over a 270 Mbit signal.

MPEG-2 compression seems to be totally acceptable up to 50-to-1, and marginally so up to about 100-to-1. DVCpro 25 (25 Mbit, or about 10-to-1) is widely considered to be crappy by broadcast standards, but looks a damn sight better than my TiVo on my home TV.

My rambling point (coffee, please) is that "HDTV" is a soft, fuzzy concept. Squeeze it down to 5 or 6 Mbit and it'll still be HDTV, with a thousand lines of resolution on-screen. But it might be so fuzzy or artifact-y that nobody would watch it.

Re:of bit rates and band widths

[SteveSgt]

The standard for uncompressed HDTV is a document called SMPTE-292M -- it's a 1.485Gb/S synchronous stream typically carried over coax. There is an IETF draft RFC for carrying uncompressed SMPTE-292M over IP HERE.

The University of Washington, with the assistance of Sony and Enron, presented a demonstration of seven channels of HDTV compressed to 200Mb/S over an OC-48 backbone at the National Association of Broadcaster's convention in April of 2000. In this demo, they produced a HiDef newscast on the floor on the Las Vegas Convention Center, while the newcasters, cameras, and the broadcast transmitter were all in Seattle.

I know there were limited demonstrations of highly compressed HDTV over internet protocol almost a year before that. One group that has been working on that is a University consortium called The Research Channel.

By the time the MPEG toolkit compresses a video signal down to 50:1, a LOT of data has been discarded. You see strange artifacts (if you're watching carefully enough) such as arms disappearing while the football player is throwing the ball, or water behind a moving boat looking more like clouds. Yes, for some still images you still get the 1920X1080 resolution, but mostly you get interpolated fuzz lower than the resolution of standard-definition video.

TV over Internet still a fair ways away

[alteridem]

Everyone said high speed Internet access with DSL and Cable would bring in an age of high bandwidth Internet applications like TV over IP. This article just shows that this is not going to be the case for sometime. If HDTV requires a throughput of 20 Mbps, then our fast connections at home are still a long way off. Besides, when is the last time you even managed full bandwidth when doing an upload? Something upstream is always a bottleneck.

Just think about it, a T1 is 1.5 Mbps, my cable modem max's out at 2.9 Mbps (not that I ever see that.) These bandwidth hungry applications are still a long way away, at least until the next Internet revolution when we all have fiber to the home...

Re:TV over Internet still a fair ways away

[JoeShmoe]

Here in Sacramento, Western Integrated Networks is doing just that.

Fiber (well really it's that hybrid coax/fiber system that cable companies already use...just fatter pipes the whole way down and more focus on two-way syncronous connections) to the home with a single connection that does telephone, Internet and digital TV.

According to a couple techs I've talked to, the telephone service is basic VoIP. Since a T1 is 1.5Mbit and that's I think 32 lines then I don't expect this will take up much bandwidth. Supposedly the interface to the "modem" is going to be 10BaseT (it remains to be seen if I will be able to hook my own hardware into the line at its true 100Mb+ speed or I have to use their hardware) so that isn't a lot of traffic. Now each TV channel is apparently a full 5-6MBps MPEG-2 video stream. This I imagine is going to chew up the majority of their system bandwidth, especially if they plan to offer the same channels as AT&T digital cable or DirectTV.

It's kinda amazing to think about how much data that single coax from your cable provider carries. In order to provide the equivalent hundreds channels of video, WIN is having to rollout some pretty high powered stuff.

- JoeShmoe

Re:TV over Internet still a fair ways away

[Chundra]

It's called an antenna. Back in the old days we used to use them to broadcast all sorts of signals.

To millions of people.

Without lag.

Stop whining about HDTV

[Kagato]

Everytime there is an HDTV story posted I read people WHINE about how bad HDTV is. Just stop it. The reason HD (or DTV for that matter) have not taken off is the MPAA (or rather who they rerosent.) HD content is sparse. Why? Studio's don't want to produce it. And it's not a matter of technology. It's not a matter of costing huge ammounts of money for the studio to make an HD copy. In fact many prime time programs are filmed, then converted to video during editing. Usually drama's, sci-fi, made for TV movies, etc.

Studio's hate HDTV. Why? Because it ruins a very important Video market. They now count on the fact that VCR's make low quality, grainy copies of on-air content. This means they can make tons of bank on [insert fav show here] box sets. Once you deal with a digital format they are sunk. People can now make a high quality recording for personal use. Hence no reason to buy an over priced box set from the local retailer.

While people can contend the studios and networks are free to do as they please, I would counter that the networks are allowed to use OUR airwaves for next to nothing. With out over the air content no one would buy a box set show. Like it or not, Timeshifting is legal and is considered a RIGHT we have gained in exchange for allowing networks to use the airwaves.

HD prices could have dropped like DVD prices by now if the studios didn't stand in the way. The mear fact that hardware vendors keep having to go to the design stage to add new copy protect and transports to please the studios is just crazy.

HD is $$$ and in it's intfancy because of the DMCA and studio money. It's doesn't matter if you're a Dem. or Rep., because neither party took a stand and did any thing to protect the consumer.

Ogg Tarkin!

[KjetilK]

Yep, and the loudthinking has started. It has even been given a name Ogg Tarkin, and there are mailing lists for it.

And since open standards is my favorite issue, I support these efforts a lot (though I haven't the knowlegde to participate).