[opendtv] Re: Execs see challenges bringing Net video to TV
- From: Albert Manfredi <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 27 Sep 2008 17:34:03 -0400
John Shutt wrote:
> How many "full resolution HD" streams does your data
> center host? What are the bitrates, and how many
> simultaneous unicast streams of these full HD programs
> can your data center support?
Let's do some hypothetical numbers. So, the congloms are interested in making
their online content available not just to PCs, for the occasional catch-up
viewing, but to real TVs, in the den. This means that the ISP has a whole new
problem on his hands, where now potentially every household in the metropolis
will be tuning in to an HD stream at the same time. A game changer for the ISP.
IP multicast is rarely enabled between ISP domains (certainly with IPv4, TBD
still with IPv6). But within his own network, an ISP can certainly use
multicast.
So, an ISP interested in supporting this potentially massive viewership among
his own subscribers, once he sees his network become hopelessly overloaded by
subscribers trying to simultaneously access the congloms' servers during prime
time, takes action.
A first step might be for this ISP to log onto many of the TV networks' servers
and fetch whatever they have to offer. Then stream this content as
real-time-only IP multicasts over his own network. (And block direct access to
the TV networks' servers from individual subscribers.)
Let's assume this ISP is still using only 1 Gb/s Ethernet in his core network.
He can support 50 streams of multicast 18 Mb/s HDTV, with some change for other
stuff. Or, obviously, many more streams if a mix of this very high quality HD
and lesser HD, or even SD.
But, since the ISP is probably using a passive optical network, he should be
able to upgrade the core of his network to 10G Ethernet without too much
trouble. And soon, 100G Ethernet, which is in the works at the IEEE. So
clearly, if using IP multicast, there is no major issue.
The VOD part requires local servers. Let's say each server passes 500 homes. So
again, if each server reaches the 500 homes via 1G Ethernet, only 50 of the
highest quality HD programs could be offered to the 500 homes at any given
time, as individual streams. But when the ISP upgrades to 10G, each home could
access an individual VOD 18 Mb/s HD stream at any time.
Obviously, this is technically harder to do than broadcast and local recording.
That's why it's taking so long. But once the technology exists, and is in
place, who cares how difficult the underlying circuits are? If the congloms are
willing to have more of their content made available directly to the viewers,
in the living room or den, over the Internet, I think for sure ISPs will take
action and make it happen.
Bert
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