[opendtv] Re: What FiOS will offer
- From: "Kilroy Hughes" <Kilroy.Hughes@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Mon, 13 Feb 2006 21:51:48 -0800
Surprisingly, multicast distribution is more the exception than the rule
on IPTV systems, and tuning latency is one factor against it. =20
MPEG-2 broadcast is bad enough, but advanced video codecs with long GOPs
and multiple reference frames for good coding efficiency have very poor
response on tuning and trick play. IPTV systems are designed to compete
with PVRs and VOD, and the fast analog tuning most people use today.
Each customer gets their own server in a rack somewhere, and its latency
to channel tune can be around 150ms, vs. several times that for
broadcast and multicast tuning (when you ask for new video, you get an
entry point/sequence header/I-frame immediately shot from the server; no
waiting for the next one to float by). Pause, rewind, skip, slow-mo are
all doable. =20
A server can also send several PIDs at once at low resolution so you can
live preview a video window overlaying the full screen video that
follows you as you skip around shows in the EPG, or you can view all
your favorite channels simultaneously on your big flat panel like a
newsroom. Just point and click to enlarge a channel to full screen (the
server is the one switching resolutions so last mile bandwidth stays the
same and the client doesn't have to scale the video).
The key is hierarchical storage management where the storage area
network mirrors the video files being watched to the edge servers on
demand. You might be the only one in your neighborhood watching the
Olympic winter tanning competition, or there might be a thousand servers
reading the same file (likely different parts of the file, different
play speeds, etc., but it makes no difference).
From a purely technical perspective, a "channel" becomes just a playlist
or a metadata filter in a preference engine, so it is possible that
operators might not just try to just duplicate cable TV and lock people
into their hotly debated "tiers". =20
The only thing preventing us from having the "Bert" channel ("Bert's
Blog" let's call it) is how the hierarchical storage management system
prioritizes those files. You can create the Bert's Blog channel
(assuming you have a camera, a server, and no shame; this would be a
bunch of video files and your suggested sequence or hierarchical menuing
system for consumption), and generic ISPs like Akamai will cache and
replicate automatically based on regional demand, access statistics,
load balancing, etc.; but you won't get HD performance unless the IPTV
netop edge replicates those files on their SAN and edge servers. =20
PS. HD DVD-Video players are capable of 1080P playback from HTTP
servers over any IP network, but they rely on progressive download,
TCP/IP packet retransmission, scheduled preloading, and large buffers to
smooth out network speed variations; so the user gets instant response,
but buffering may have begun automatically a minute before and might
survive a couple minutes of network congestion without effecting video
playout. Asking for reliable average performance from the generic
Internet is asking plenty. Ask for RTP/RTSP and multicast and most
consumers won't get anything "TV quality". =20
SD progressive download/streaming is practical today, and all HD DVD
players have the ability to decode, scale, position, and alpha overlay a
second SD video stream from the Web or wherever; so we can add directors
and Mystery Science Theater puppets walking around in existing movies on
disc, emitting commentary or giving the other actors a hard time. Also
good for adding sign language and lip reading heads or foreign language
tracks produced after a disc was released. =20
In places like Korea, Japan, etc., it's more possible to send 1080P HD
to the Primary Decoder (good for HD trailers, special features, TV
shows, whatever). With standard IP service in some countries at nominal
bandwidths around 40 Mbps at half the cost I pay for cable modem in the
US, HD over generic IP networks may be practical soon outside the US.
Servers can chat with each player and negotiate the best resolution and
bitrate they can handle, so it's a publisher's choice what resolutions
to offer, and they can scale up offered resolutions and bitrates any day
they feel like it, one show at a time. This kind of HD DVD-Video "IPTV"
capability will be an option on game consoles, PCs, Media Centers, and
CE disc players; as well as dedicated IPTV network settop boxes.
Imitating today's cable service with IPTV may be a business choice, but
it sure isn't a technical limitation.
Kilroy Hughes
Sr. Media Architect
Digital Media Interoperability Team
Microsoft Corporation
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx]
On Behalf Of Manfredi, Albert E
Sent: Monday, February 13, 2006 07:14
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: What FiOS will offer
Richard Hollandsworth wrote:
> 1. FIOS website currently offers 15 Mbps download for
> about the same price as what I'm currently paying for
> 5 Mbps via RoadRunner.
Perhaps, but that's just the link speed between the last
box in the telco and your premises. Which does not mean
that anyone out there can upload streams at that speed,
nor does it mean that you have 15 Mb/s available to or
from the Internet.
> 2. HD video via MPEG4 only requires 8-12 Mbps.
>
> Putting 1 and 2 together means HD Video can enter you
> home without going through a corporate gatekeeper
> (i.e. D*, E*,Cable or even IPTV).
The telco will no doubt set up a system whereby the HDTV
streams will be transmitted using IP multicast, confined
to within the boundaries of the telco's intranet. Which
is the usual way IP multicasts are scoped. That way, only
Verizon or SBC subscribers will have access to these
streams, and the subscriber will get reasonably quick
response time when "tuning in" to a particular program.
I don't think it's going to be anything revolutionary.
What IPTV really attempts to do is to emulate the cable
TV experience. But for non-real-time downloads, that's
in principle possible with any fast connection.
Bert
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