IP Based Video Conferencing
Thomas Petersen
Department of Computer Science
University of Wisconsin - Platteville
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Abstract
As video conferencing is becoming more and more popular, it is important that companies take advantage of it. Video conferencing has made great strides since the 90’s and is now used by many different users, not just large businesses in meeting rooms. IP based video conferencing has lots of advantages over ISDN, the biggest one being price. The price is fixed so you don’t get charged depending on how much you use it or where you are connecting to in the world. There are many different types of service you can get ranging from free to over $1,000 a month depending on the quality you need. Video conferencing is becoming more user friendly and easier to use, there is no reason not to use it with its many benefits.
Introduction
There is a wide variety of internet protocol based video conferencing. The solution that is right for you depends on your specific needs. You can get as cheap as buying a webcam for around $20 and using Skype, AOL instant messenger or Windows Live Messenger. You can also get as expensive as spending over $5,000 on the camera and another $900 a month for a service with good bandwidth and unlimited uses. This may seem high but it is actually much cheaper than what it has been in the past.
When setting up to do video conferencing there are several main components that you will need. Some of them you might think about include camera, microphone, and display to view the picture. Some of them you might not think about are the codec and the application itself. How all these parts work together really isn’t that complicated and they have many benefits, but also a few drawbacks.
History
Video Conferencing started to take off in 1990 and has become more mainstream since then. Back in the 90’s video conferencing was done over ISDN lines and was very expensive. You had to pay based on how long the conference call went, so the longer the meeting the more you had to pay. H.320 protocols were used, which had some problems with disconnecting you and sometimes you couldn’t even reconnect.
Today video conferencing systems use H.323 protocols which really open up the possibilities of video conferencing. With H.320 you had to dial a number of the video conferencing system you wanted to connect to. With H.323 you type in the IP address of the system you want to connect to, so that is a little different. H.323 allows you to connect to any computer on your network, LAN or the internet with video conferencing capabilities. When in the past you had to go to a specific meeting room to use video conferencing it now can be done from just about anywhere, your personal desktop can even be set up for video conferences if you like[1].
Table1: taken from: howstuffworks.com
As you can see from Table 1 H.323 protocol is actually a family of protocols that is made up of many different protocols. The most important protocols in this family are H.225 and H.245 which are both in the transport layer. H.225 performs call control while H.245 performs call management [6].
The last important protocol to know about is SIP which stands for Session Initiation Protocol. SIP is an internet based application that uses TCP, UDP and others to make it work. SIP user agents can be telephones, video units, PDA’s and more [5].
Main Components
Video conferencing systems are made up of five main parts. The first part is the video camera. This is pretty self explanatory you have to have a camera so that the people on the other side of the video conference can see you. The second part is the video display. You have to have some way to see the people on the other side of the conference, also known as the other endpoint. Some examples of displays are computer screens, TV’s and projectors. The third part is the audio components. You have to have a way to let the other people hear what you are saying and hear what they are saying. It is pointless to have picture if they can’t also hear what you are saying. The next part is the codec. This is that part that a lot of people don’t think about but it is one of the most important parts. Codec stands for compressor/decompressor. The codec changes the audio and video into a form that can be transmitted over the internet. Once it is sent the codec on the other side decompresses the file back into the audio and video so that it can be viewed. The last part is the user interface. The user interface should be simple and easy to use. Remember the three golden rules to a user interface, keep the user in control, reduce the user’s memory load, and keep the interface consistent.
Figure 1: done with Visio some pictures taken from polycom.com
Figure 1 shows how a video conference might take place. All you need are two or more video conferencing systems that you can connect using the internet or a LAN depending on if the two systems are on the same network or not. In general you get much better quality from a video conference if they are set up on the same network.
How it Works
IP based video conferencing works by sending data from the camera and microphone to a codec. The codec puts that data into a form that it can send over the internet or network to the other endpoint. The data then travels over the internet or network to the place you are sending it to, the other half of the conference also known as an endpoint. Once the data is received, the codec then puts the data into a form that can be viewed with a monitor and played through the speakers. One nice feature that you can use while sending the data over the internet is Quality of Service (QoS). QoS manages data traffic and makes sure that the quality of the IP video transmission is good. It does this by setting aside an amount of bandwidth for video calls and doesn’t allow other traffic to use it [2].
Another nice feature is a Gatekeeper. A gatekeeper is software that allows you to register all the users that you might want to contact for a video conference. For example if you wanted you could set up the system to connect to Conference Room 1 instead of that computer’s IP address. This makes it easy for people that aren’t experts in computers to do exactly what they want. Another feature is that you can set an arbitrary phone number to connect to instead of the IP address. So you could set up the system in such a way that you type in the phone number of a specific room and the video conferencing system will connect to that room because that number is linked to the IP address of the computer in that room which is what your computer really wants to know. Again that just makes things easier for everyone trying to set up a video conference. The last nice feature is that you can limit bandwidth for specific users. This is very nice if you want to make sure that the conference rooms get the bandwidth they need. Basically what it does is limits other peoples bandwidth and saves it for the places you really need it. So say someone setting up a video conference from their desk wouldn’t get as much bandwidth as the people in the conference room down the hall [4].
Benefits
The biggest benefit of using IP based video conferencing is the cost. IP based video conferencing has one flat rate that the business using it can control. With ISDN video conferencing you pay-as-you-go, so how much you pay depends on how much you use it, so if you use it a lot one month you will get a big bill that you might not of planned for which might cause you to go over budget.
Another benefit is improved quality and technical advantages. There are many things that effect video quality some of them are bandwidth, frame rate, resolution, picture size, and codec’s used. Some of the other technical advantages include the ease of use. ISDN is difficult to understand and need a special technician to fix a lot of the problems. With IP based it is easier to use so your in house technicians can help you, this saves a lot of money in the long run.
A big benefit is how many people already use it. ISDN was never available in every geographic region and the regions that did have it only had it in specific conference rooms. IP based is available just about everywhere and can be installed on any computer not just in meeting rooms. One of the reasons so many people are using it is how easy it is to use. Just about anyone can use it with a little training [3].
It cuts down on travel cost. When you have video conferencing you don’t have to spend money flying employees to meetings, pay for hotels and food while they are away. It also allows the employee to be more productive because they don’t have to spend half a day traveling, they can use that time to get work done.
Problems
One of the problems with video conferencing is that you can’t have eye contact with the person you are speaking too. Eye contact is important because it shows that the person you are talking too is interested in what you have to say.
A second problem is that some people don’t like to be on camera. The camera can effect how they act and it might make them uncomfortable.
The biggest problem with IP based video conferencing is bandwidth problems. Video Conferencing works much better with high speed internet. If you don’t have high speed internet then you will not get very good quality. The picture will not be able to keep up with real time, so it will look choppy and not very good. If someone is interacting with you, you want to be able to see them and what they are doing.
Some solutions have arisen to help with the bandwidth problem. Two of them are multi-cast and real-time. Multi-cast allows multiple endpoints to receive data at the same time with about the same overhead as sending the data to a single endpoint. This makes it much easier to have a conference with multiple users with out many problems. The Real-time solution guarantees that packets are delivered in a timely manner.
Cost
Cost can be split in to two main categories, initial setup cost and monthly fees. Initial setup includes buying all the equipment needed for video conferencing. When buying the initial equipment there are two different ways to go. First you can buy an all in one unit that has everything you need in it. The other way to go is buy all the parts separately. This is better when you want to have more control over the equipment or you already have some of the equipment and only need a few extra things. The monthly fee is that amount you pay to use the service each month. This can vary a lot depending on how many locations you are setting up and how much bandwidth you need the system to handle.
Initial Setup
The two main producers of video conferencing equipment are Polycom and Tandberg. Most of their products are expensive and meant for medium to large businesses, but they do have some solutions for a more reasonable price. If you’re just looking for a camera then the Polycom ViaVideo II is a good choice. It retails for about $400.
If you are looking for an all-in-one solution one good pick is the Polycom Viewstation. The nice thing about the Viewstation is that you don’t need to hook it up to a computer all you need is the Viewstation and a TV to view the video and hear the audio from the other conference room. The Viewstation’s price ranges anywhere from $2,000 to $7,000 depending on which version you want.
Service Fee
The second category is the monthly fee. You have to pay to use the service. The price can depend on many different things including, bandwidth and how much you use it. Prices are usually between $500 and $1,000 a month. If you want to save some money you can get cheaper solutions but quality drops quite a bit.
The service fee is a big difference from IDSN video conferencing. With the initial setup it doesn’t really matter if you are using IDSN or IP based you are going to pay about the same. In fact most commercial equipment used for video conferencing can be used with either type. The service fee is probably the biggest difference between the two. With IDSN you pay for how much you use the service. So if you only make a few conference calls you only pay a little. If you make a lot of calls you pay a lot. IP based has one constant monthly fee that you can plan for. You will never be surprised by how much a bill is and you don’t have to worry about going over budget.
Figure2: Monthly charges for using IP instead of ISDN Taken from:glowpoint.com
Figure2 shows that the price of IP based video conferencing stays constant for the most part while ISDN charges change depending on how much you use it. The one exception to the constant fee for using IP based is if you are using a IP based system to contact a ISDN system you still have to pay a fee but it is much less than if you were using ISDN.
Common Questions about Video conferencing
There are many things that people don’t know about video conferencing and IP based video conferencing in particular. If people don’t know how to do something sometimes they seem to avoid it or let someone else do it for them. This section is designed to help people feel more comfortable with video conferencing and to encourage them to try new things and push their video conferencing system to get everything that they can out of it.
How many users can be linked together in a conference call?
When connecting to a conference call you can add as many others as you would like, however, the more users you are connected with, the harder it is on the system. If there are a lot of users you might experience some lag depending on your network speed.
One way to make it easier to connect to multiple users is the use of a MCU. MCU stands for Multipoint Control Unit. The sole purpose of the MCU is to make it easy to have a conference with more than two endpoints. There are two main ways a MCU can work. One way is to show you who is talking. Since your setup most likely will not allow you to view every endpoint at the same time on different screens it has to find a way to let you view the most important user at the time. It does this by seeing who is talking at that time and shows you his video. The other option is to have a grid with all the endpoints on it at once. Think of this like split screen. If you have a three way conference you can view the other two endpoints at the same time on the same screen right next to each other [4].