[opendtv] Re: IPTV on AP: Interactive TV Poised for a Rollout (Feb 13)
- From: John McClenny <jamcclenny@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Tue, 15 Feb 2005 13:38:09 -0600
Comments inline
On Tue, 15 Feb 2005 13:01:42 -0500, Manfredi, Albert E
<albert.e.manfredi@xxxxxxxxxx> wrote:
> John McClenny wrote:
>
> > Everything that would be broadcast in a cable
> > system is multicast in an IPTV system. One channel
> > -- one stream. Only in the VOD case is there
> > unicast.
>
> Yes, of course. But I was responding to this comment:
>
> > > An IPTV network can offer unlimited channels.
> > > Then again, the same is true for a cable system,
> > > if it is based on the routing of services, INSTEAD
> > > of broadcasting them to everyone.
>
> That comment shows a misunderstanding of IPTV and the
> lack of consideration of basic system constraints.
> The "instead of broadcasting," in this context, is
> unicasting. He's talking about individual streams.
> Any subscriber can download any content available
> over the Internet.
>
> The truth is, the multicasts in IPTV are analogous to
> broadcasts in cable systems. And, as we already
> discussed, must operate within a "walled garden." I
> even pointed to an Internet Draft that addresses the
> general multicast issues over IPv4 and v6. So in
> practice IPTV and digital cable are not all that
> different. And by the way, any subscriber of either
> scheme can go and fetch video content over the
> Internet. So even that is no different.
Cable and IPTV systems are (functionally) identical, just implemented
differently. IPTV does make a lot of features easier to implement -
from a middleware application level, managing bandwidth is easier than
dynamically managing video spectrum. VOD scales better. Two-way
applications are easier. The long delayed interactive TV applications
are a lot easier to implement. This is all a matter of degree, not of
kind, but the accumulation of all of these incremental advantages can
lead to a substantially different user experience.
If we distribute caching content servers toward the edge of the
network, it is much easier to supply lots of different video streams
to homes than through a MSO VOD system. Reponse is faster, the
experience more seamless. On my Time Warner VOD service, I have a
10-20 second delay for when I hot the "pause' key - you wouldn't see
that on a IPTV system.
> > The core bandwidth of the IPTV networks is pretty
> > large - only at the edge are their constraints, and
> > then only if DSL is used. The vastmajority of
> > comsumers won't be effected by the bandwidth
> > limitations.
>
> So how is this different from cable networks? They too
> are fiber optic and very wide in the core. But because
> they deploy coax into homes, rather than Cat5e, they
> have far more bandwidth at the edge.
But that bandwidth is harder to manage. That's one of the reasons
that the cable guys want to go to IP long term. If all video is
encapsulated in IP streams, I can more easily cache closer to the edge
of the network.
> My point was that the reason to go IPTV for telcos
> is nothing like what the hype-meisters keep pretending.
> The reason is that narrower local loop requires the
> functionality of a typical cable STB to be located
> upstream. That's it. The letters "IP" don't in
> practice offer much more than that, compared with
> what existing digital cable can offer.
Agreed.
> > The IPTV people also have the late mover advantage -
> > they can easily adopt new codecs and higher
> > performance STBs as their base level of architecture
> > without the cost of replacing an existing equipment
> > base.
>
> Sure. Then again, they *have* to use new codecs to be
> competitive, with their narrow edge connections. And
> cable systems have proven to be perfectly willing to
> undertake costly upgrades, when there's a reason to do
> so. A new AVC-enabled cable STB will cost no more for
> a cable system than it would for an IPTV system.
Cable guys can't afford to spend the money that the telcos can right
now. They have spent big bucks on upgrades and need to recoup some of
that investment. Digital RF STBs are going to cost a little more than
a Ethernet STB - tuners cost more than Ethernet conenctions.
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