HDTV Over IP 124
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.
good for some things, but bad for broadcast (Score:3, Interesting)
I've seen something like this before -- a 36 Mbit DV stream sent over the Internet2 (IP network instead of Firewire) from Ohio to Pennsylvania. It was just a test, to see if it could be made to work. Latency was in the 150ms range. (Basically it was two FreeBSD machines with Firewire and tuned 100Base-T cards on both ends.)
At the time, my reaction was "What a waste of bandwidth!" but extremely high quality video streams at relatively low latency are critical for remote instrumentation/manipulation applications. Like moving a robot arm in space, or allowing scientists from all over the place to use one piece of very expensive equipment instead of moving them all to the same location. We also considered using something like that in an on-campus video editing facility for moving footage around from machine to machine. I can see the use for it in some situations.
But for broadcasting? I don't see the point of using all that spectrum just for a video.
of bit rates and band widths (Score:5, Interesting)
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.
TV over Internet still a fair ways away (Score:4, Interesting)
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...
Stop whining about HDTV (Score:5, Interesting)
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.
Re:of bit rates and band widths (Score:4, Interesting)
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 [ietf.org].
The University of Washington, with the assistance of Sony and Enron, presented a demonstration [washington.edu] of seven channels of HDTV compressed to 200Mb/S over an OC-48 backbone at the National Association of Broadcaster's [nab.org] 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 [researchchannel.com].
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.
This makes Open Source video even more important (Score:3, Interesting)
This makes getting open source video formats in place even more important so that, in the very near future, we don't have to make a decision like the one we're making right now between OGG and MP3. One format is techincally superior and open, while the other is the 'industry standard'.