The Vidyo Story

Something had to be done. Web conferencing took off like gangbusters, but not Video conferencing in spite of the fact that it has been around much longer. In brief, it is because Web conferencing has been far more accommodating. In fact, it is essentially available to anyone with an Internet connection, which is to say pretty much everyone. Web conferencing provides for easy interaction between vastly different clients, as distinguished by compute power, available bandwidth and screen resolution. Web conferencing is indifferent to all these variations, so people are able to join conferences from wherever they happen to be, on whatever system they happen to have. Historically, however, this has not been the case for video conferencing, which was designed originally around the embarrassingly dated notion that all conferences would have the benefit of special video conferencing facilities and dedicated high-bandwidth networks.

Setting a New Standard
One of the reasons traditional video conferencing has never really taken off in quite the way Web conferencing has is that it was designed for an entirely different world than the one we find ourselves in now. That is, unlike the Web, traditional video conferencing was designed to rely almost entirely on centralized Multipoint Control Units (MCUs), dedicated high-bandwidth lines, and special conferencing facilities. And doesn't that sound like a throwback to the old mainframe days? So, guess what — it turns out the clunky old video conferencing systems are painfully out of place in a Web-powered world. Surprised?

When people think about conferencing, they think in terms of universal connectivity, the ability to call from anywhere to anywhere. People also want to be able to include all different kinds of users in their discussions, ranging from the people in corporate headquarters who can gather in video conferencing rooms to those individuals who will be connecting over the Internet from home offices. That kind of flexibility and affordability has never been associated with traditional video conferencing.

Given all these concerns, Vidyo founder Ofer Shapiro (who was also the inventor of RADVISION's Gatekeeper and MCU) long ago saw that a whole new approach was called for, one that would enable high quality video conferencing over converged networks. He became one of the earliest advocates for a new Internet Protocol (IP) video compression algorithm to provide for high quality video at relatively low transmission bit rates, eliminating the need for dedicated lines. Ultimately, this vision was realized with the creation and adoption of the Scalable Video Coding (the Scalable Video Coding (SVC) extension to the H.264 video coding standard. And now, as CEO of Vidyo, Inc., Ofer Shapiro has the privilege of presiding over the release of the first video conferencing products designed to take full advantage of SVC technology. Video conferencing will never be quite the same again.

A Better VidyoConferencing Experience
Even as video communications have become more integral to enterprise applications over the past few years, the limitations of the current crop of video communications solutions have become uncomfortably apparent. The high cost of the systems and solutions themselves, not to mention the need for special rooms and dedicated networks. Users have also been forced to bear with decidedly marginal performance, choppy frames, long delays, blurred motion, and broken pictures have lessened the video conferencing experience, giving people good reason to expect more.

VidyoConferencing provides higher-quality experiences with greater flexibility at a lower cost by providing products and services based on a better technical foundation, the H.264 Scalable Video Coding (SVC) standard. By using this standard a full range of user environments becomes available, from the home-office desktop up to the dedicated corporate video-conferencing facility.

VidyoConferencing products have all been designed to take advantage of an organization's existing IP infrastructure, no dedicated networks are required. Yet Vidyo still manages to surpass the quality of video communications as we have come to know, at just a fraction of the cost. By addressing the performance, cost, ease-of-use, and networking issues associated with traditional conferencing solutions, Vidyo has at long last made broad-based video communications affordable for both enterprises and consumer applications alike.

High Time for a Change
What's wrong with traditional video conferencing? Let's go straight to the heart of the matter: the Multipoint Control Unit (MCU). From a computational standpoint, this is where all the heavy lifting in a traditional video conferencing network is done. And that's just the problem. Web-savvy applications handle much of the compute load out at the endpoints. MCUs, on the other hand, are like a lingering vestige from a bygone era when mainframes roamed the earth and endpoints were regularly treated as nothing more than dumb terminals. It's high time we woke up and smelled the coffee.

Look at it this way: MCUs are expensive. From a configuration perspective, they're neither flexible nor fungible. They don't scale particularly well, and whenever resolution technology improves, it takes a forklift replacement for MCUs to keep pace. Also, because MCUs are only nominally error-resilient (unable to sustain anything more than 5% packet loss), they all but require the use of expensive dedicated lines. But now, let's get down to the real problem with MCUs … For all intents and purposes, it turns out that MCUs are nothing more than quality-degradation machines. And that's because the transcoding they perform invariably degrades video quality. Also, transcoding is extremely time-consuming (adding up to 200 ms to the time it takes for each frame to leave the MCU). And all that takes place right in the middle of highly time-sensitive video transmissions, which ends up taking a huge toll on the user experience. So, let's briefly recap here: greater expense, less flexibility, limited scalability, increased latency, diminished quality. Not terribly inspiring, is it? This isn't to minimize the important contributions made by the MCU over time. But it is to say that the MCU's day has most certainly passed.

What's SVC Got to Do With It?
Dr. Thomas Wiegand, arguably the world's foremost authority on video compression and one of the chairmen of the Joint Video Committee responsible for the H.264 standard for video compression, spoke with us about what the recent adoption of the Scalable Video Coding extension to H.264 means for video conferencing.

Traditional video communication uses H.264/AVC. So why it is that traditional video conferencing based on H.264/AVC was not considered to be efficient enough?

Traditional video coding using H.264/AVC is very sensitive to transmission errors since errors are typically visible for some period due to error propagation within the video. Mitigating this is very costly and typically requires a sudden increase in bit rate to stop error propagation. However, since most errors in Internet transmissions are caused by congestion, increasing the bit rate is not the right way to stop that. Also, H.264/AVC bitstream protection through forward error correction (FEC) or automatic repeat request (ARQ) has so far not been shown to work well due to the significant bit rate overhead and the associated delay. Consequently, dedicated lines offering high Quality of Service are often used. But because dedicated networks are typically constant bit rate (CBR) and are very costly, the bit rates are generally kept as low as possible.

All these considerations apply to point-to-point as well as multipoint transmissions. In the latter case, however, the problems are aggravated since the CBR constraints of multiple transmission lines need to be considered — and that often results in people running their systems at the lowest common denominator CBR. That means the transmission rate of the transmission channel with the lowest rate effectively becomes the maximum rate everybody else can use.

So what constitutes a more efficient system for video conferencing over general-purpose IP networks?

Efficient system architecture for video conferencing over general-purpose IP networks has to look very similar to the rest of the Internet — that is, with little processing being required inside the network and instead being handled out at the edge of the network, and with the network itself being a best-effort network. That means the video encoder and decoder at the endpoints should do almost all the processing, with the media routers in the network left to do only lightweight packet operations with practically no delay. And, of course, all transmissions should actually run over the general-purpose Internet. Such a system should also share other Internet properties, including low cost, high efficiency and scaling characteristics. Therefore, SVC-based video conferencing and the Internet is a perfect match. It's also worth noting that traditional video conferencing architectures are the complete opposite of the Internet architecture. They place computationally heavyweight transcoding MCUs inside the network and also require dedicated lines.

 

Why Vidyo Technology is Better?
Vidyo's unique intellectual property leverages the recently approved H.264/SVC standard to create VidyoTechnology, an SDK that concurrently delivers a coded representation of source video signals at a variety of temporal, spatial, and quality resolutions embedded in a single bit-stream. The different bit-stream components and the VidyoRouter allow the system to dynamically adapt to varying network conditions such as packet loss, jitter, network bandwidth, and network delay. Similarly, the use of multiple bit-stream components permits the flexibility to adapt to changing processing power at the video source as well as at the receiving endpoints. VidyoTechnology's technical advantage over traditional systems also allows for these new features and benefits:

Feature Benefit Low time delay Meaningful interactive communication at the speed of life Rate matching Efficient use of bandwidth Personal video layout Gives the user — instead of MCU limitations — control over the layout Error resiliency Provides continuous high-quality video without broken pictures or other artifacts Error localization Conference participants are not affected by packet losses that may occur in other participants of the same conference. Dynamic rate control Automatically senses current network conditions and adjusts bit rates accordingly Improved random entry Existing conference participants are not affected as new participants join conference Improved media switching/routing among participants Existing conference participants are not affected as new participants join conference