Don't fear video

Computer Technology Review, August, 2004 by Richard Mavrogeanes

It's easy for any IT manager to kill the boss's interest in deploying video in their enterprise network: just whisper, "It will kill the mission-critical data applications." Of course, it need not be true. But it is a response sometimes given due to fear that it might be true, or as a means to shed what appears to be an additional or uncertain workload. Video in a network is in reality just a special form of data, and just like voice-over-IP, one that requires real-time, reliable delivery. Happily, modern enterprise networks are completely up to the task.

Let's start by dismissing several myths about video.

"Video is a Bandwidth Hog"

If your network consists of analog modems, shared Ethernet hubs and 100-MHz desktop computers, you may be right. If this is your network, you probably also believe that a 100-KB e-mail file attachment is a bandwidth hog!

In a switched Ethernet network, every host has its own private 10/100 Mbps connection. Modern switches cannot even be oversubscribed (the sum of the many switch ports is equal to the capacity of the switch), so at least at the local level most network managers agree there is no problem.

The perception of bandwidth being a problem typically comes from the over-subscription of Wide Area Network (WAN) connections. If you have a T1 connection to the public Internet, then it takes only six people in your building to tune in to a 250Kbps public "webcast" before your entire T1 is consumed by inbound unicast video streams. Indeed, mission-critical applications that depend on access to external servers will grind to a halt. For this reason, it's not uncommon for IT managers to deny users access to public webcasts. Thus, "video is a bandwidth hog" becomes the conventional wisdom and, like most conventional wisdom, it's misleading.

Video is almost never a bandwidth hog when it is used wholly within a building or campus. Even a 5Mbps broadcast-quality MPEG-2 live video stream sent over your LAN uses exactly 5% of the capacity of one Ethernet switch port--a number that is "barely felt" by today's standards. Within your network, use of multicast means that this single 5Mbps video can be viewed on all desktops and TV monitors without bandwidth worries.

"Video Standards Have Not Matured"

Every DVD is in reality an MPEG-2 file. Virtually all satellite broadcasting is MPEG-2. "Digital Cable TV" delivers MPEG-2 video streams to millions of homes. MPEG-4 is a well-established standard implemented by multiple vendors and, like MPEG-2, facilitates a multiple-vendor solution for video.

Unlike H.323 and H.320 "videoconference" systems, modern video standards such as those developed by the Internet Streaming Media Alliance (ISMA) were developed for IP networks, while legacy systems were primarily developed for "telecom" and were well suited for ISDN delivery systems.

It may be reasonable to resist a major video deployment when such deployment depends on a single-vendor, proprietary solution. Today there is wide interoperability between vendors, thanks to adherence to standards.

"Network Video Quality is Poor"

If you are referring to thumb-nail-sized, proprietary video in the public Internet from several years ago, this might be a true statement. Today, you have full-screen, 30 frame-per-second, stunning DVD-quality live and stored video with a quality that often surpasses what you get at home. Modern video appliances and systems provide two-way, low delay, DVD-quality television with CD-quality audio. If by "video" your mind goes to legacy talking head "videoconference" systems, or to "webcasting," you haven't seen modern network video.

"Network Video is Exotic"

Video is no more exotic than any other application. Gone are the days when you must understand, install and support unusual PC video drivers, capture cards, decoders, and special video servers. Most new users are shocked to discover they can have live DVD-quality video running on their network in about 15 minutes--including reading the instructions.

"Network Video Applications Are Limited"

We forget that the initial "killer application" for our digital networks was not e-mail, surfing the web, file exchange, e-commerce, or any of the current "mission critical" uses of our networks. Modern LANs were inspired simply to share printers.

So it is with network video. The initial deployment may be to broadcast the CEO's weekly address to employees; to monitor critical areas; to provide both live and archived training and education; or to conduct face-to-face meetings with broadcast-quality television. The natural human instinct to see and hear makes video the most compelling form of human communications.

But What is Video?

Few people alive today are not already familiar with "television," or literally "remote vision." But what is video?

Video is simply a series of still images displayed fast enough that the human eye does not detect flicker. To send video on a network, however, each still image must be compressed.

Framing the Issue

A TV image consists of a continuous series of frames presented at a rate of 30 per second (actually 29.97 per second). To convert one frame into digital format, it must be broken into individual pixels. Each pixel uses 2 bytes of storage to describe its location, color and intensity. If the industry standard sampling rate is used, 13.5 million pixels result (CCIR-601 standard). This number of pixels requires exactly 699,840 bytes (720 pixels X 486 lines X 2 bytes per pixel) to digitize one frame. With a rate of 29.97 frames per second, the data rate required to display TV-quality images with full motion is 20,974,204.8 bytes per second. One CD could only hold about 30 seconds of video, and serial transmission of this data would require over 167 Mbps in each direction. In fact, Rec-601 Component Video Serial Data Interface operates at 270 Mbps! This certainly shows the vast data-carrying capacity of broadcast television.