Guide to video conferencing - h.460, h.264, h.320, h.323 video conferencing equipmentKeywords - video conferencing,H 460,H 264,H.261,H.320,H.323 |
Video conferencing has shifted to a standard called H.323, designed to allow audio and video
to pass over both LANs and the Internet. Integrating videoconferencing
with IP technology opens up the potential for exciting new two-way video
applications in Web publishing, e-commerce customer support, intranet
groupware, and IP telephony. Meanwhile, the dominant ISDN-based H.320
technology is finally maturing, with prices dropping and quality and interoperability
improving steadily. This guide highlights videoconferencing systems that
list for under $10,000 and support either H.320 (ISDN) or H.323 (Internet/LAN)
standards.
To Whom Does This Apply
The main appeal of videoconferencing is to reduce business travel costs,
but vertical applications such as distance learning are also driving this
technology. There's also increasing interest in the T.120-based document
conferencing packages bundled with many of these products. Programs such
as Microsoft NetMeeting and White Pine's CUSeeMe provide whiteboards,
document sharing, text chat, and file-transfer features. A common scenario
on the low end: open up a session with video to see who you're talking
to, then switch to audio conferencing and document sharing. You can also
use these programs independently, but you'll need to coordinate a separate
voice call if you want audio.
So far, single-user H.320 desktop systems have sold poorly, but lower-cost
H.323 systems are growing in popularity. The early growth in H.323 systems
has been in $100-to-$300 "Webcam" products that combine a low-cost monitor-top
camera with a video capture card. Usually, these plug into the parallel
port, but the latest systems claim better quality by using the higher-bandwidth
USB port. This year, business-oriented H.320 systems have begun to add
H.323 support backed up with hardware codex boards, and companies are
buying gateways that link H.323 and H.320 users.
Key Buying Criteria
For video quality, see how the system reacts to sudden movement. For audio,
check out its ability to handle overlapping conversations. Generally,
quality improves with the presence of a hardware codex.
The latest systems offer a H.263 video codex that delivers somewhat
superior quality to the older H.261. Some H.320 systems also boost quality
by supporting the new 384Kbps service, in which ISDN service providers
combine three 128Kbps lines. Most H.323 systems support up to 768Kbps
bandwidth over LAN, but on a multi-use LAN, however, the quality is generally
inferior, and there's far less reliability. Faster computers help, but
networks need to be upgraded with 100Mbps Ethernet switches and fast new
routers. Beyond the experimentation stage, you'll also want to install
gatekeeper software on your server to help manage H.323 traffic. The public
Internet poses even great challenges to video, requiring use of emerging
virtual private networks to achieve dependable business-quality (jitter-free
15fps) beyond the enterprise.
Helpful features to look for are picture-in-picture and still-frame capture,
and the ability to adjust audio vs. video quality and image quality vs.
frame rate. On the low end you may want a product that supports H.324
dial-up connections over 56Kbps modems. If you buy an ISDN system, look
for one that lets you use the ISDN card for 128Kbps Internet access as
well as conferencing.
More expensive group systems not only provide better quality, but also
table-top controls and a superior camera equipped with zoom and remote
access. Some systems offer voice-activated camera control, and others
include built-in Web servers so you can easily schedule meetings and drag
and drop documents off Web servers.
Future Trends
Look for a continuing drop in the price of group systems that support both H.320 and H.323 standards, as well as set-top devices that provide greater ease of installation. Also look for more systems with built-in MCU (multipoint control unit) servers to lower the price and improve the reliability of meetings between more than two sites. In the next year or two, DSL- and cable-modem-based H.323 systems should arrive with the potential for much greater video quality.
Preparing the Enterprise for IP Videoconferencing
For a generation that grew up watching Kirk, Picard, Sisko, and Janeway hobnob with aliens over crystal-clear videoconferencing displays, the quality of today's videoconferencing technology is somewhat disappointing. Improvements in computer processing power and algorithms will help, but what's really missing is bandwidth -- and not just a fat pipeline, but a fat undisturbed pipeline.
In the networked enterprise, the infrastructure required for videoconferencing with the new H.323 standard is available today, but implementing it will cost you. You’ll need switched Ethernet to even start thinking about LAN-based video, and you’ll really want fast 100Mbps switches and smart routers that incorporate the Internet Engineering Task Force (IETF) standard called RSVP (Resource Reservation Protocol). While RSVP is not technically part of H.323, most H.323 products support it in order to improve the quality of conferencing sessions across a large intranet. Larger enterprise networks may also want to invest in ATM- or Gigabit-Ethernet backbones to link workgroups. First Virtual Corp. recently introduced an IP-to-ATM gateway, enabling ATM backbones to carry video traffic from Ethernet desktops.
Gatekeepers and Gateways
Zippy network hardware alone won't solve the many glitches and latency problems
typical of LAN videoconferencing. As H.323 usage increases over your network,
you'll need to invest in gatekeeper software to help smooth the rough
edges. This software can sit on any H.323 terminal, but is generally run
as a server application. Typically, your first gatekeeper arrives as part
of gateway software that translates between H.323 and H.320 ISDN connections.
Gatekeeper software eases conference setup by translating LAN aliases
into IP or IPX addresses, and it manages bandwidth for optimal quality
of service, meaning that streaming media such as videoconferencing can
be guaranteed to pass over the network with at least a modicum of quality
and consistency. H.323's bandwidth management tools include the User Datagram
Protocol (which incorporates the IETF's IP Multicast and Real-Time Protocols)
and the Real-Time Control Protocol, which handles quality of services
issues. Most H.323 gatekeepers also support RSVP, which provides bandwidth
reservation services over RSVP-compliant routers.
PictureTel's server-based LiveManager gatekeeper software, for example,
let network managers tailor H.323 LiveLAN client calls based on the client's
authorization level and computing capabilities. The manager can protect
core network services by limiting the bandwidth that can be used by conferences,
as well as prioritize the bandwidth for key conferences (for example,
a scheduled meeting of the executive staff might receive greater priority
than an ad-hoc session among lower-level employees). LiveManager can also
monitor links with PictureTel’s H.320/H.323 gateway, LiveGateway, as well
as keep track of activity running over an optional H.320 MCU (multipoint
conference unit), which combines more than two conference participants
in a single session. MCUs designed for H.323 (see below) generally include
their own gatekeeper software.
If your company already has a number of legacy H.320-based group conferencing
systems in-house, you can link them with your H.323 users via a gateway.
However, to link them more directly, you may want to equip them with an
H.323 option. RADVision, a leading vendor of H.323 protocol stacks and
toolkits (along with companies such as DataBeam, Intel, and Lucent's Elemedia)
recently introduced a new Video Interface Unit that connects legacy H.320
group systems to H.323 sessions.
IP Telephony in H.323 Driver's Seat
Since
it will take years for most LANs to upgrade their networking technology
to support video, the fastest-growing application for H.323 gatekeeper
software will be in handling the growing traffic in voice calls over the
Internet. The IP-based voice or fax gateways that corporations are buying
to save money on long-distance calls typically include H.323 gatekeepers
that act as virtual PBX systems for monitoring traffic.
The recent explosion in voice-over-IP services is driving the H.323 standard
more than videoconferencing. Adopted in January of 1998, H.323 version
2.0 boosted security, added support for ATM and RSVP, and incorporated
multicasting support for broadcasting an H.323 feed to up to 1,000 users.
But version 2.0 also added PBX-oriented call forwarding and call transferring
features. Next year's version 3.0 places even greater emphasis on call
management and IP telephony, with a special focus on inter-gatekeeper
issues between different H.323 zones and circuit-switched PBX systems.
Since the standard (and the industry at large) placed the video cart before
the talking horse, it will take years before gatekeeper software will
be able to match sophisticated PBX technology. While H.323 has no significant
competition on the video front, it’s being challenged by several standards
for control of IP telephony. As demand grows for advanced H.323 gatekeeper
software designed for use by ISPs and telephony carriers, IP telephony
vendors may part ways with H.323 in favor of emerging IP voice standards
such as IPDC (Internet Protocol Device Control) and SGCP (Simple Gateway
Control Protocol).
It will take time before H.323 can implement the protocols needed to orchestrate
thousands of calls that characterize carrier environments. "There's an
issue of scalability with H.323," said Josh Adelson, product marketing
manager for IP telephony at Brooktrout, a company that sells underlying
H.323-based telephony technology to fax- and voice-server companies. At
the same time, H.323's emphasis on video within a PC LAN setting may make
it too complex for simple voice applications. The conferencing overhead
also makes for a more complex and expensive client. "In a telco-class
switching environment, H.323 is a little too verbose," says Adelson. "It
goes through a number of steps in setting up the call. These other standards
are more streamlined for voice."
The rift between the forces of IPDC/SGCP and H.323 tends to mirror the
Wintel versus Java/NC battle. Microsoft and Intel support H.323 because
it's a peer-to-peer standard that exploits a robust PC client. Most of
the networking companies, on the other hand, including erstwhile Wintel
collaborator Cisco, are pushing a thin client architecture that offers
greater central control. ISPs and cable companies, which plan to roll
out IP telephony services over the next few years, also tend to prefer
this centralized approach.
The problem with switching to the new voice-specific standards, says George
Kloak, RADVision's vice president for sales, is that customers will be
unprepared in a few years when pipelines are capable of delivering high-quality
videoconferencing. "The 60 companies we’ve sold H.323 technology to all
have visions of implementing video alongside audio," says Kloak. "If you
go for a cheaper client today, you'll have to do a forklift upgrade later."
In the end, says Kloak, H.323 will adopt parts of the competing standards,
especially in the development of a thin client.
Multipoint Drops in Price
Once
you've invested in gatekeeper software for monitoring traffic and H.320/H.323
gateways for linking up with ISDN callers, demand will grow for multipoint
conference units that can connect more than two callers. Most H.320 videoconferencing
users still dial in to third-party MCU servers. While this approach is
the most reliable, scheduling is inflexible, and the costs are high. Over
the last year, there has been a new wave of lower-cost MCUs targeted at
corporations that want to bring the MCU in house. The technology is still
quite new and unreliable, especially when trying to implement continuous-presence
conferencing in which up to four video signals are displayed simultaneously
in a four-way split-screen format.
MCUs are also beginning to appear within videoconferencing systems themselves.
Polycom just introduced the ViewStation MP, an H.320 group conferencing
system that includes an MCU server. The $11,999 price tag is only $3,000
more than its ViewStation 512 system.
Theoretically, multipoint is easier (and cheaper) in an H.323 LAN setting,
which is more naturally inclined to handle multi-user applications. H.323
multipoint servers make scheduling far more flexible than with circuit-switched
systems, and they can also link more participants than an ISDN multipoint
session, mixing video, audio, and T.120 conferencing callers. Most of
the products can support between four and 24 interactive callers, depending
on how many use video. With H.323's newfound IP Multicast support, White
Pine's MeetingPoint Conference Server permits a single video caller to
lecture and present documents to hundreds of nonvideo participants. It
also provides continuous-presence multipoint, but only when all clients
use White Pine's CU-SeeMe client software. The biggest cost savings come
from the fact that H.323 multipoint conferences can be implemented solely
in software as a server application. Aside from MeetingPoint, other software-based
H.323 multipoint servers include DataBeam's NeT.120 Conference Server
and PictureTel's 330 NetConference servers. VideoServer, an industry leader
in MCUs, sells a more expensive hardware-based solution.
T.120 Conferencing Over H.323
If
you want to implement T.120 document conferencing sessions among numerous
locations, but don't require video, you may be interested in Web conferencing
and collaboration servers. These include ActiveTouch's ActiveMeetings,
Broadband Associates' M.Show, Contigo's Internet Conference Server, Lotus'
Sametime, Lucent's OneMeeting, MCI WorldCom's networkMCI Conferencing,
Sessio's iSession, and VocalTec's Conferencing Server. Some of these programs,
such as ActiveMeetings and iSession, are available only as third-party
hosting services, but most can be implemented in-house. Some are fairly
straightforward conferencing MCUs, while others, such as Lotus' Sametime
and ActiveMeetings, offer additional collaboration features. M.Show and
Contigo’s ICS are designed for making Web presentations. One interesting
new product is iVisit, a peer-to-peer multi-user video client that permits
multipoint video conferences without a server application. Created by
Boxtop Interactive, now part of the recent merger combo, iXL, IVisit is
optimized for handling low-bandwidth video sessions, dropping down to
4-bit grayscale if necessary.
For one-to-one
conferencing, there are a variety of stand-alone T.120-compatible conferencing
products, many free for downloading. Some of these -- especially Microsoft
NetMeeting -- are bundled with videoconferencing products, but you can
also use them independently. NetMeeting is by far the most popular T.120
client, followed by White Pine’s CU-SeeMe. Netscape has jumped into the
game with its Netscape Conference and Netscape Collaborator.
T.120 products
provide an interactive whiteboard that lets you sketch out ideas and mark
up documents onscreen. They also give you file transfer, real-time text
chat, and, with some of the programs, document sharing. Keep in mind,
however, that adherence to T.120 can be sketchy, and features such as
document sharing can only be guaranteed to work reliably when working
with the same client on the other end of the line.
Proprietary Videoconferencing Solutions
If
your company needs high-quality videoconferencing today and can't afford
to reinvent your network with new switches and routers, you may be considering
a proprietary server-based solution from companies such as C-Phone, First
Virtual Corp. and Objective Communications Inc.
These companies, several of which also offer standards-based desktop solutions,
provide switched enterprise-wide video over phone lines or other dedicated
networks. They're targeted at environments where conferencing needs are
tangible and quality is at a premium, such as surveillance, health care,
manufacturing, and campus-wide distance learning.
With the VidPhone System from Objective Communications, for example, a
PBX-like communications server enables high-quality, full-screen 30fps
videoconferencing to PCs throughout an enterprise. Their secret: It's
all analog, so no loss of compression is involved. Unlike most competing
approaches, VidPhone doesn't require an overlay network, but uses existing
phone lines. Each server can link 50 users at a cost of about $3,500 per
user for a 50-user setup. (You can also purchase a VidPhone network for
as few as five users.) Options are available for broadcasting from any
video source and multipoint bridging for connecting up to four participants
in continuous presence mode. There are also ISDN (H.320) and ATM gateways
for connecting with remote users. A video server gateway option is due
in early 1999, along with T.120 support and the ability to link VidPhone
servers for networks of up to 768 ports. Also in the works is a suite
of call management services, including billing and resource scheduling.
In an on-site demo, the quality was far superior to ISDN video, and network
managers will like the fact that it doesn't burden the Ethernet network
with video traffic. While the VidPhone is no bargain, especially when
you add in all the options, it is reasonably priced if you have several
dozen users spread out throughout an enterprise who need to stay connected
on a regular basis.
The problem with VidPhone and other proprietary systems is that they are
isolated from where the industry is heading: H.323. Rather than make a
large upfront investment in a proprietary solution today, most companies
will want to instead spend the money on upgrading their network for H.323
conferencing tomorrow. That same investment will also benefit overall
LAN and intranet traffic as well as other streaming media applications
such as interactive training and multimedia database access. Objective
makes a reasonable argument that H.323 won't be ready for serious conferencing
tasks for many years to come, and that they'll be ready with an H.323
gateway when the need arises. While a gateway won't bring you all the
potential of a network rich with H.323 conferencing applications, for
most of us, that network is years away, and VidPhone's 30fps video is
here today.
