Video Conferencing Fundamentals

For many years, communications vendors have been hailing video conferencing as the next big thing. In fact, my first toe-dip into video conferencing was way back in the early 1990s. I was a software developer at Northern Telecom and we came up with a product that we called VISIT Video. It was Lync long before Microsoft “invented” Lync and we were sure that VISIT would revolutionize the way people communicated. Sadly, the product was eventually killed due to lack of sales. We had a really cool, cutting edge product that people weren’t ready to use.


My next trips down the video conferencing lane were with other people’s products. I was an early adopter of Microsoft’s OCS and helped build and configure Polycom room systems. Unfortunately, I was often an island unto myself and it was hard to find anyone willing to hop onto a video conference with me.

That was the norm for the next several years. People were becoming more aware of video conferencing, but the adoption rate was still very low.

However, I now see a major shift in the willingness to learn about and deploy video.  In fact, in my role as unified communications evangelist, I don’t even have to bring it up any longer.  Enterprises have been thinking hard about video and are ready to roll it out.

The Times They Are a Changing

What changed?  Frankly, a lot.  Video is so much easier to use than it was a few short years ago.  It used to be that if a company had video equipment, it only had a couple of people who knew how to operate it.  Now, video is built into our PCs and smartphones.  Video has gone from finding the one guy or gal who understands “that Polycom stuff” to clicking on a name.

People have changed.  Millennials don’t have the same fear of video that many baby boomers have.  They are as comfortable with selfies and YouTube videos as older folks are with email and telephones.  Every year these young people make up a larger portion of the workforce and their comfort with seeing and being seen is contagious.

Work styles have certainly changed, too.   Companies are embracing the results oriented, geographically distributed workplace.  Project teams are spread out across the country and the world.  Room systems, desktops, and mobile devices allow those teams to feel a cohesion that isn’t possible with other forms of communication.  We are a visual species and seeing the face of your coworker is important to building an effective working relationship.

Lastly, networks have changed.  Switches and routers have been upgraded to be Quality of Service aware.  The Ethernet pipes to our desks have been beefed up.  Wireless and 4G are everywhere.  It’s easy to overlay video on top of a network ready to handle real-time communication.

Unfortunately, I find that not everyone is as smart about video conferencing as they need to be. They are finally familiar with the big concepts of video, but can’t really explain it or fully comprehend what a salesperson is trying to sell them.

So, for the next page or so, allow me to speak about some of the terms and components that I am sure you will encounter as you make your way towards video conferencing.


A Codec (Coder Decoder) is what converts the analog signal that a video camera captures to a digital signal that can be transmitted on an IP network. This data is often compressed to minimize network bandwidth usage.

When I was working on the VISIT Video product, H.261 was the codec of choice. This was pre-IP, though, and we ran H.261 across 64kbits/s ISDN lines.  It did well for the time, though, and we were able to get close to the gold standard of ten frames per second.

A few years after H.261, H.263 was created as a low bitrate compressed format for video conferencing on IP connections. H.261 was only concerned with the video portion of the call. An audio codec such as AMR was needed to transmit voice.

H.263 was expressed in three different sizes.

SQCIF (Sub-Quarter Common Intermediate Format) creates an image of 128 x 96 pixels.

QCIF (Quarter Common Intermediate Format) creates an image of 176 x 144 pixels.

CIF (Common Intermediate Format) creates an image of 352 x 288 pixels.

Of course, like most things in the world of unified communications, technology and standards are constantly being upgraded and for the most part, H.263 has been replaced by the newer H.264.

H.264 (also known as MPEG-4 Part 10) can not only work with low bitrate video, but it can also successfully encode high quality videos. Although H.264 is considered a lossy codec (data is lost during compression and decompression), the loss is considered to be insignificant.

Scalable Video Coding (SVC) is an extension to H.264. SVC makes video available on tablets and mobile phones.

Besides video conferencing, H.264 is used by Blu-Ray disks, Adobe Flash, Microsoft Silverlight, YouTube, and Vimeo.

With the advent of WebRTC, H.264’s place is being challenged by the newcomer, VP8 (and soon VP9). The jury is still out as to who will win the codec battle, but for now it’s clear that H.264 remains the dominant protocol in video conferencing.

Stay tuned for future developments, though. No one stays king forever and VP8 has a number of things going for it.

A companion piece to this article can be found at Calculating Bandwidth for Video Calls.

SIP vs. H.323

A codec expresses how video is encoded, but you need a signaling protocol to create, manage, and release video calls. That’s where H.323 and SIP come in.

H.323 has been the dominant player in this space and the likes of Polycom, Tandberg, Lifesize, and Radvision built their original systems with it. However, like IP telephony, IP video is making the move towards SIP. SIP may have started as the protocol for desktops, but the big room systems are quickly converting to SIP.

Most products support gateways that allow SIP systems to work with H.323 systems and vice versa.

One and One and One is Three

While it’s technically possible to make a point-to-point video call without anything other than a network between the two clients, most solutions position a server of some sort in the middle for management, reporting, and address resolution. After setup, point-to-point video can travel directly between the two clients.

However, it becomes difficult, if not impossible, to create multi-party video calls without something between the endpoints. This is where a Multi-Point Control Unit (MCU) comes in.

An MCU is a bridge or media mixer that allows three or more endpoints to be part of the same video call. An MCU for video is similar to a conference bridge for audio calls. Depending upon the capabilities of the MCU, the participants in a video conference may see all the other parties in the call or simply the active speaker.



While different vendors make it sound as if telepresence is somehow different from video conferencing, that’s like saying that a Cadillac is different from a car. Telepresence is video conferencing with a strict set of rules as to how it is implemented. For instance, telepresence defines how the conference room must be set up. It specifies how the camera, speakers, tables, and chairs are arranged. It sets guidelines for the network that carries the video traffic. In the end, though, a Cadillac is a fancy car and telepresence is simply well-defined video conferencing.

Desktop vs. Room System

For many years, video conferences took place in dedicated rooms that only a few people in a company knew how to operate. Now, video conferences can be created, and often managed, on PCs, tablets, smartphones, and video-enabled desk phones.

Video systems have evolved to be able to simultaneously handle media streams from participants of all types. The same call might consist of Linda in a video conference room, Andrew on his iPhone, Dave on his iPad, and Susan on her Android phone. An MCU would handle any transcoding or conversions and each endpoint would display video according to its specifications.

Studies have shown that providing video on devices that users are already comfortable using greatly increases its adoption rate.

Video Conferencing in the Cloud

Like every other aspect of IP communications, video conferencing is finding a home in the cloud. Blue Jeans, Lifesize, Zoom, GoTo Meeting, and a number of other offerings exist today that allow you to schedule and participate in a video conference with little more than a PC, camera, and a set of speakers. Pricing models differ for the various offerings, but each claims to lower the overall cost of video conferencing.

Enough to Make You Dangerous

I hope this helps you understand the big aspect involved with video conferencing. While it may sound complicated with all those protocols and components, video has actually become fairly easy to install, manage, and most importantly, use. Key to that ease is the fact that video conferencing is standards based and there are well-defined rules as to how products of different companies can work together.

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