You might think you understand video conferencing pretty well until someone unfamiliar with it approaches you with a simple definition. When they ask, “What exactly is video conferencing?” you might suddenly realize that you have no words. The simplest definition of how video conferencing works is simply the integration of video, audio, and peripherals to allow two or more people to communicate simultaneously over some form of telecommunications lines. In other words, you are transmitting synchronized images and verbal communications between two or more locations instead of being in the same room. How video conferencing works is a bit more difficult to explain than answering the question “What is video conferencing?”. Millions of people use video conferencing every day around the world, but very few know how the technical aspects of the process work. The main ingredients of a successful video conference are video cameras, microphones, appropriate computer software, and computer equipment and peripherals that will be integrated with the transmission lines to transmit the information. Analog information recorded by microphones and cameras is broken down into discrete units, translating it into ones and zeros. A codec encodes the information into a digital signal that can then be transmitted to a codec at the other end, which will translate these digital signals back into analog video images and audio sounds. The theory is the same, transmission has changed In the early days of video conferencing, T1, ATM, and ISDN lines were used almost exclusively, but were really only practical for room-based video conferencing systems. These dedicated lines were expensive and only large corporations used to have the facilities and money to invest in this type of installation. However, as the Internet became a part of everyday life for all businesses, the way video conferencing was conducted changed. Internet TCP/IP connections are much less expensive and can carry large amounts of information, including video conferencing packets, with relative ease. Because of this, video conferencing has become much more prevalent in small business and desktop packages that can be set up with computer-to-computer networking software. Compression makes streaming video convenient The problem that arises when converting from analog to digital for streaming is the loss of clarity in an image. Analog signals are a continuous wave of amplitudes and frequencies that show shades and color ranges, as well as depth and brightness. When you convert to digital, which is strictly 0 and 1, you need to develop a grid to represent values, intensities, and saturations of different color values ​​so that the image can be interpreted and reshaped at the receiving end. This large amount of digital information requires high bandwidth and means that the time it would take to transmit video images would not be practical for most applications. That’s where compression is crucial. When determining how video conferencing works, one of the most important elements is the compression ratio. The higher the compression ratio, the faster the information can be transmitted. In many cases, however, this also means some loss of clarity or audio/video quality. For example, a compression ratio of 4:1 would be excruciatingly slow but still have fantastic image quality. But by the time it aired, everyone on the other end would probably have left the room for a cup of coffee. Lossy compression discards unnecessary or irrelevant sections of a signal to transmit only the essentials, which significantly speeds up transmission time, but sometimes results in a loss of quality. Compression can be intra-frame or inter-frame for repetitive or redundant material, such as the wall behind the conference participant. Since the wall remains static and never changes, this image is redundant and can be removed from streams to some degree with proper compression. Intraframe compression assumes that redundancy will be present in parts of a frame that are close to each other. Interframe compression assumes there is redundancy over time (ie like that wall). Any of these can achieve a fairly high degree of accuracy while reducing the bandwidth required for signal transmission. A newer version of compression/decompression is SightSpeed ​​technology, developed by Cornell University. SightSpeed ​​​​​​compresses only the images considered essential and removes what is considered ‘filler’, relying on the brain to complete the decompression at the other end. Based on an artificial intelligence model, SightSpeed ​​​​achieves a compression of around 90:1, compared to the typical 15:1 for video conferencing. Any video conferencing session you use will provide compression of the broadcast signal. The key is to determine the balance between speed and video image quality that is right for your needs. Point-to-point videoconferencing Point-to-point videoconferencing is exactly what it sounds like: a link between two different points on the planet or two different videoconferencing endpoints. It could be between an office in New York City and a conference room in Munich. Peer-to-peer video conferences can easily be started if someone on one end contacts the other end as if they were making a standard phone call. There are no special arrangements to make other than knowing that the participants will be there. Multipoint conferencing is more complex Multipoint conferencing is more complicated because you have to coordinate several different locations simultaneously. Since you can’t be in direct contact with multiple places at once while everyone is in contact with others, you need a source that unites them all. In video conferencing, this is called a multipoint bridge or a multipoint conference unit (MCU). An MCU enables video conferencing at multiple locations by providing a sort of “central processing center” for all locations through which all information flows. The MCU receives all the information from the various locations and then sends it to each location. In some cases, the MCU is located on a particular PC, and in other cases, it is located on a remote server (the most common structure, particularly for more powerful MCU networks). Audio is typically sent and received simultaneously at all locations with an MCU without issue due to the relatively small bandwidth required for transmission. It is transmitted in what is called “full duplex” mode, which means that everyone can talk and listen at the same time with no dropouts when one person or another is speaking. However, streaming video can be transmitted in a number of ways with an MCU depending on the quality of the software and the complexity of the system. Some common types of video streaming for video conferencing include:

• Continuous Presence video conferencing, which allows you to view up to four conference sites simultaneously on split screens. This is typically used if you have a small group or individuals in separate locations and will primarily be viewing close-ups.
• Universal control the video conference is controlled by the conference initiation site. The main site determines who sees what on all other sites.
• voice activated Video conferencing is by far the most common type used today. The image with these systems changes to the site that is currently activating the microphone so you can always see who is speaking. However, if there is a lot of background noise, participants should mute their microphones when they are not speaking to avoid unnecessary image jumping.

Overcoming the language barrier Obviously, communication via video conferencing cannot be achieved unless both ends of the conference “speak the same language.” That is, anything that is transmitted electronically will need to be reassembled correctly and clearly heard and seen at the other end. The Codec (Coder-Decoder) system is useless if both ends are not using the same virtual language to interpret the signals. The International Telecommunication Union (ITU) developed a set of standards in 1996 called H.323 to outline specific guidelines for videoconferencing standards and protocols to make compliance and support between networks easier to achieve and maintain. Since then, many manufacturers and developers of video conferencing tools have adopted the H.323 guidelines as their own. Web conferencing solutions such as Click to Meet, Lotus SameTime, and WebEx also offer corporate solutions based on Internet video conferencing. These systems have shared protocols that can be downloaded and used anywhere at any location for subscribers over the Internet. These are becoming increasingly popular with businesses that like convenience and ease of use. They will no doubt get more and more refined over time, competing with and perhaps surpassing H.323 standards. Overcoming firewall issues There are, of course, hurdles to overcome when you take a look at how video conferencing works. After all, you are sending large amounts of translated data, either directly or through a control system (the MCU) that switches and transfers information between a variety of computers. Almost any business these days has a firewall system in place to provide security and protect the system from possible viruses. The problem is that many firewalls also block data transmission for video conferencing. Recent innovations have largely avoided these problems by designing firewall solutions that recognize video conference signaling requests and allow information packets to bypass the firewall or router without disabling firewall protection for other traffic. Even with this, however, there may be times when packets are dropped due to heavy traffic on the system, so investing in a firewall system that can handle substantial traffic is essential for quality video conferencing performance. . How video conferencing works will certainly evolve over time and improve in the years to come, but a basic understanding of what it is and how it works now will help you make the decision that’s best for you when you’re ready to start video conferencing yourself. This article on “How Video Conferencing Works” is reproduced with permission.

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