MPEG-4: Multiscreen Cuts to the Front of the Line9/12/2011 12:01 AM Eastern
Cable operators have always envisioned a
future that embraces MPEG-4. The original reason: The
video compression format is far more efficient than the
current standard for digital cable, MPEG-2.
But as it happens, Internet-protocol TV and multi-device
video services have
emerged as the applications
that will largely
represent cable’s initial
uses of MPEG-4.
“A lot of us were
thinking of MPEG-4 as
a bandwidth saver, but
now that all of us MSOs
are looking at TV Everywhere
and video to mobile
and tablet devices,
that has really changed
the way we look at
MPEG-4,” Charter Communications vice president of advanced
video engineering Doug Ike said.
Many smaller operators are of a similar mind. Bend-
Broadband, based in Bend, Ore., in January 2009 completed
a conversion to all-digital — using MPEG-2-only boxes
— so it isn’t in any rush to migrate to MPEG-4, chief technology
officer Frank Miller said. “For us, MPEG-4 is not a
headroom-saving tool. We don’t see a lot of pressure from
a product perspective to go there.”
Some operators already have moved to MPEG-4 for
“over-the-top” distribution in the home. For example, the
iPad apps from Time Warner Cable and Cablevision Systems
deliver linear TV in the format.
HD PRESSURE’S OFF
Cable operators had a much greater sense of urgency about
adopting MPEG-4 three years ago, when satellite-TV providers
DirecTV and Dish Network were ratcheting up their
HD channel counts and MSOs had to scramble to catch up,
according to Mike Paxton, In-Stat digital entertainment
Instead, operators used switched digital video, analog
reclamation and other tools to boost their own HD offerings
and neutralize the marketing threat (see “The HD
Wars Are Over. What’s the Next Battleground?” July 11,
2011). “The fact is, cable is much more comfortable
with their HD positioning against their competitors.
Their fears weren’t realized,” Paxton said.
Of course, operators will continue to deploy MPEG-4-
capable set-tops for their traditional TV services. Just like
analog video services — which the industry is still gradually
phasing out — at some point in the future it will make
sense to throw the switch and deliver all video in MPEG-4.
Indeed, virtually every new cable set-top on the market,
even at the low end, includes
chips that have both
aspect of delivering
[a cable set-top] today
that is MPEG-2 but also
just table stakes,” Mark
Schaffer, director of
for Motorola Mobility’s
network infrastructure business, said.
While operators are still moving toward an MPEG-4 environment,
“there’s no sense of, ‘We have to get this done
by the end of 2012 or else,’” Paxton said.
Comcast is farther ahead than many of its peers in deploying
MPEG-4. On the set-top box side, all of the RNG-class set-tops
the operator has been buying since 2007 are MPEG-4-capable,
according to Steve Reynolds, Comcast senior vice president
of customer premises equipment and home networking.
Currently, about 30% of Comcast’s overall set-top installed
base is MPEG-4-capable, and about 50% of its HD
So far, Comcast has only selectively used MPEG-4 to deliver
video to those set-tops. For example, it broadcast the
3D feed of The Masters golf tournament earlier this year
in MPEG-4 in order to save bandwidth — so subscribers
who wanted to watch the stereoscopic telecast needed to
have a compatible box.
For its regular services, Comcast expects to phase in
MPEG-4 first with video on demand.
“We will start with unicast, because we know the capabilities
of the box that is requesting the stream,” Reynolds
said. “VOD will migrate to MPEG-4.”
Meanwhile, Comcast is using MPEG-4 video in trials
for its Xcalibur service, which uses a “cloud-based” interface
and IP-delivered content. Video targeted to the
“Parker” set-top boxes in the test are delivered via the
built-in DOCSIS cable modem, rather than via QAMs.
“The MPEG-4 decoder in the box can handle streams
from either the QAMs or IP,” Reynolds said.
For Charter, less than 20% of subscribers have MPEG-
4-capable boxes. At some point, the MSO may deliver
advanced services such as 3D and 1080p HD or niche
programming in MPEG-4, Ike said; VOD is still under discussion.
The issue for the near future is that any MPEG-4
services will be unavailable to most Charter customers.
“We don’t have a way to deliver MPEG-4 to the mass of
our subscribers,” Ike said. “We have millions of legacy devices
that don’t do MPEG-4.”
No single answer will apply in adopting MPEG-4 delivery
to set-tops because operators have a different starting point
and different capacity constraints, said Harmonic vice president
of cable solutions Gil Katz. “Now the trick is really the
migration,” he said. Moving to MPEG-4 sooner for broadcast
TV “really makes sense for operators that are starving
on spectrum, instead of investing into the network.”
COSTS DOWN, COMPRESSION UP
Cable hasn’t been hurt in being a “slow follower” on
MPEG-4 behind satellite and IPTV, Paxton said. That’s because
the cost of set-top decoders for MPEG-4 has dropped
over the last few years, he noted.
In the meantime, MPEG-4 compression algorithms
have become even more efficient.
The rule of thumb used to be that MPEG-4 uses roughly
half the bandwidth as MPEG-2. Today’s MPEG-4 encoders
can do even better, providing up to a threefold improvement
over the older format, according to Motorola’s Schaffer: “We
are continuing to refine MPEG-4 encoding efficiency.”
The ultimate goal is to deliver all video programming in
the same format. BendBroadband is deploying hybrid IP/
QAM gateways from Arris Group that can receive MPEG-
2 channels today but will be able to handle IP-delivered
MPEG-4 video down the line, Miller said.
“At the end of the game,” he said, “you have MPEG-4
adaptive bit-rate technology to distribute everywhere.”