Advances in software across a wide range of vendor
initiatives suggest that barriers to delivering quality video, along with interactive
multimedia advertising, at sub-megabit bit rates will soon fall.
On one front, the MPEG-4 initiative (the fourth generation
of the Moving Picture Expert Group standard) has picked up steam, and it is now closing in
on completion of version two, with some developers signaling that they'll have MPEG-4 tool
kits on the market before the year is out.
Elsewhere, innovations such as tight coupling of
video-streaming client software with set-top operating systems and on-the-fly shaping of
bit streams to fit moment-by-moment changes in end-user access rates contribute to
prospects for far better performance in the hundreds of kilobits-per-second range than is
"We've already demonstrated that we can achieve TV
quality with video delivered in the sub-megabit range in the right context," said
Martin Dunsmir, general manager for emerging technologies at RealNetworks Inc. "We've
progressed a long way in the past six months."
The "right context" when it comes to getting such
low-rate, high-quality video to TV sets involves many things. Those include support for
efficient media distribution across the backbone networks and tight integration of
decoding and other streaming-processing components within the small amount of computer
processing capacity resident in set-top boxes, Dunsmir noted.
But, he added, in the case of cable distribution, such as
AT&T Broadband & Internet Services' Headend in the Sky operation, the backbone
support is already there and the set-top capacity is in the pipeline.
"You might actually see HITS sending MPEG-2 video at
600 kilobits per second," Dunsmir said.
And, he added, similar quality levels could be achieved at
these bit rates over broadband-enabled IP (Internet protocol) backbones and distribution
systems, such as what Excite@Home plans to launch in conjunction with technology supplied
by RN in December, and what Enron Communications Inc. and its Internet-service provider
partners are preparing.
"We're not yet at the end of the rainbow where
streaming movies and other media on-demand are transparently available for viewing on TVs
and PCs [personal computers], but we're at the first step," Dunsmir said.
Two recent deals coupling RN's client player software with
set-top operating systems are part of that first step.
Both WebTV Networks - a unit of Microsoft Corp., which has
battled RN over supremacy in multimedia streaming - and Liberate Technologies (formerly
Network Computer Inc.) will incorporate RN's "G2" system into their operating
systems, making it possible for set-tops to access any G2-based streaming content on the
Set-tops using Liberate's OS - such as the next-generation
boxes Philips Consumer Electronics Co. is making for cable, as well as for satellite and
DSL (digital subscriber line) applications - will have Web-access capabilities built in.
That stems from work Liberate has done to provide for
graphics rendering and transcoding from IP to NTSC (National Television Systems Committee)
at the set-top, Liberate vice president of marketing Charlie Tritschler said.
"What we've focused on is squeezing the [processing]
footprint to handle basic functions, where what would have taken 12 to 14 megabytes, we
can now do in 1.2 megabytes," Tritschler added.
But getting to the footprint required to accommodate the G2
player, even with tight integration into its software stack, requires CPU (central
processing unit) power beyond that of the current generation of digital set-tops that
Liberate has OS deals to run on. They include General Instrument Corp.'s
"DCT-2000," Scientific-Atlanta Inc.'s "Explorer 2000" and Pioneer
Digital Technologies' "Voyager."
However, one year from now - when DSL-enabled set-tops, as
well as more advanced cable and satellite set-tops, are available at retail - the CPU will
be widely available for supporting direct access to Web-streamed multimedia from the TV.
For example, along with agreeing to include RN's
"RealAudio G2" format in current WebTV boxes, Microsoft and RN have come to
terms on an agreement that calls for developing a new RealPlayer G2 client for the Windows
This will affect not only WebTV's move into the digital
set-top environment - where a separate computer unit will no longer be required to deliver
its services to TVs - but it will also apply to other Windows CE set-top applications.
Efforts to accommodate ever-better multimedia at lower
streaming rates will get a powerful boost from the commercialization of MPEG-4, version
two of which is expected to be finalized by year's end, according to Eric Petajan, a
member of the technical staff at Lucent Technologies who represents the company in the
"I suspect that some developers are already making
tool kits that will simplify the use of MPEG-4 so that people can begin working with it to
develop applications even before version 2 is finalized," Petajan said.
MPEG-4 is designed to accommodate low-bandwidth
environments by separating the sequence-manipulation mechanisms associated with user
interaction with content from the content itself.
This way, the graphic components to be used in rendering
sequences can be stored in bursts to the end-user terminal, leaving only a small amount of
information in the form of instructions as to how graphic components are to be composed
and sequenced to be streamed in real time.
"You can scan over and replay content already
downloaded to the terminal, allowing the level of resolution in the display to be
determined by the capabilities of the CPU, rather than by available bandwidth,"
In this fashion, a multimedia game or CD-ROM-type content
played over a 28-kbps link can be displayed at graphic-quality levels and frame rates
comparable with high-definition television, he added.
While it uses some of the same compression techniques that
are applied in MPEG-2 and MPEG-1, MPEG-4 is not technically backward-compatible with those
Instead, it is designed to ride over a tiny bandwidth slice
within an MPEG-2 stream, allowing end-user terminals that have the CPU to handle the
MPEG-4 processing to take advantage of the interactive multimedia components the new tier
brings to MPEG-2.
"In the near term, using MPEG-4 to deliver interactive
applications, such as enhanced advertising, within broadcast-TV applications makes a lot
of sense," Petajan said. "You can deliver such advertising without breaking up
any of the MPEG-2 infrastructure. And those customers who don't have the processing power
to access the MPEG-4 component won't know the difference."
MPEG-4 also gives content developers a standardized tool
environment for doing things they now have to do by bringing together a lot of disparate
elements themselves, such as 3-D rendering and synchronizing various multimedia components
with each other no matter which interactive choices the user makes.
The protocol also includes the use of wavelet compression
technology and something called "2-D mesh" on top of the underlying discrete
cosine transform that is common to MPEG-1 and MPEG-2 to allow developers to easily add
zoom-in capabilities with their graphics, Petajan added.
One key to the flexibility of the new standard is the
establishment of reference models that become object segments within the graphics space,
which can be manipulated piecemeal as if they were being streamed together in real time.
For example, Petajan, in a recent demonstration, showed how
the facial reference points he has developed for the MPEG-4 group can be made to move
together in a graphic replication of someone speaking in real time. Only the instructions
that affect how each reference point is rendered are sent as the person speaks.
Such capabilities have implications for online chat and
community interactions, virtual call centers and other e-commerce applications, where a
real person's likeness would come to life much as if a real video conference were under
way, while using only the bandwidth required to transmit the audio and the instructions.
In other uses of the technology, sports events could be
transmitted at low bandwidths, leaving the playing field or court with background crowd as
a stored graphic-background template that would change in terms of overall scene
orientation on commands delivered in real time. The actual images and action of the sports
figures would be streamed in real time.
Another factor contributing to the streaming of
high-quality media at low bit rates will be capabilities such as those under development
at Imedia Corp., known in cable for the "CherryPicker" technology that gives
operators flexibility in combining digital-TV channels from various sources at the
Imedia is working on a means of applying its
bit-rate-shaping technology to the IP environment, where stored files would stream at
whatever speeds the last-mile connection of the end-user allows at any given moment in
"What our technology does well is support transcoding
from one bit rate to another," Imedia cofounder and vice president of marketing Adam
Tom said. "This will enable Web multicasting of media that adapts to the channel rate
available to the end-user."
The capability would reside at the edge of the network,
overcoming one of the key barriers to the effective use of multicasting.
Today, everything must be streamed at a set minimum rate
that underplays the playback potential of users on higher-bandwidth links, Tom noted. Even
using RN's G2, which supports multiple streaming rates, the content developer must choose
set rates in advance. This means that even at the high end, the lowest common denominator
"Today, you either multicast at minimum rates, or you
don't use multicast at all," Imedia senior vice president for sales and marketing
Stephen King said. "We're exploring the development of product with other parties
that will go a long way toward overcoming this problem."