It's certainly not reasonable to assume the same video goes to all consumers, but on the other hand, there *is* plenty of video that goes to a *lot* of consumers. I don't really need my own personal unicast copy of the bits that make up an episode of BSG or whatever. I would hope that the future has even more tivo-like devices at the consumer edge that can take advantage of the right (desired) bits whenever they are available. A single "box" that can take bits off the bird or cable tv when what it wants is found there or request over IP when it needs to doesn't seem like rocket science... -dorn On Tue, Apr 22, 2008 at 6:33 AM, <michael.dillon@bt.com> wrote:
I think you're too high there! MPEG2 SD is around 4-6Mbps, MPEG4 SD is around 2-4Mbps, MPEG4 HD is anywhere from 8 to 20Mbps, depending on how much wow factor the broadcaster is trying to give.
Nope, ATSC is 19 (more accurately 19.28) megabits per second.
So why would anyone plug an ATSC feed directly into the Internet? Are there any devices that can play it other than a TV set? Why wouldn't a video services company transcode it to MPEG4 and transmit that?
I can see that some cable/DSL companies might transmit ATSC to subscribers but they would also operate local receivers so that the traffic never touches their core. Rather like what a cable company does today with TV receivers in their head ends.
All this talk of exafloods seems to ignore the basic economics of IP networks. No ISP is going to allow subscribers to pull in 8gigs per day of video stream. And no broadcaster is going to pay for the bandwidth needed to pump out all those ATSC streams. And nobody is going to stick IP multicast (and multicast peering) in the core just to deal with video streams to people who leave their TV on all day whether they are at home or not.
At best you will see IP multicast on a city-wide basis in a single ISP's network. Also note that IP multicast only works for live broadcast TV. In today's world there isn't much of that except for news. Everything else is prerecorded and thus it COULD be transmitted at any time. IP multicast does not help you when you have 1000 subscribers all pulling in 1000 unique streams. In the 1960's it was reasonable to think that you could deliver the same video to all consumers because everybody was the same in one big melting pot. But that day is long gone.
On the other hand, P2P software could be leveraged to download video files during off-peak hours on the network. All it takes is some cooperation between P2P software developers and ISPs so that you have P2P clients which can be told to lay off during peak hours, or when they want something from the other side of a congested peering circuit. Better yet, the ISP's P2P manager could arrange for one full copy of that file to get across the congested peering circuit during the time period most favorable for that single circuit, then distribute elsewhere.
--Michael Dillon
As far as I am concerned the killer application for IP multicast is *NOT* video, it's market data feeds from NYSE, NASDAQ, CBOT, etc.
_______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog
_______________________________________________ NANOG mailing list NANOG@nanog.org http://mailman.nanog.org/mailman/listinfo/nanog