So you can now talk over the internet.

And that's not all.  Have you tried using video as well as audio?

How to Add Video to your VoIP Voice Calling
	If you're already using your internet data line for VoIP voice communications, why not add video to your calls as well?   Part 6 of a 7 part series - click for Parts  One  Two  Three  Four  Five  Six  Seven

Faster internet connections give you enough bandwidth to allow you to add video to your voice calls.

Here's how to enjoy video with your voice conversations.  Quality varies remarkably among different video services and settings, so read on and use this information to get the best video experience possible.

Realizing the Dream of the Picture Phone

Picture phones, offering combined voice and video transmission - have been talked about, and occasionally offered, for decades, with the first appearance probably dating back to the New York World's Fair in 1964.  But the technology has been too expensive, systems usually incompatible with each other, and the quality too poor to encourage broad acceptance.  Without a ruling standard and a growth towards general use, none of the various products have ever achieved any significant sales or success.

The underlying premise of the picture phone - sending video over a regular phone line - at first appeared impossible.  But the development of DSL, allowing high speed data over regular phone lines, and the complementary development of cable data services, now makes it possible for reasonably good quality video to be sent and received; in our homes, and our offices.  At the same time, 3G wireless services are making video increasingly a standard part of their mobile phone service, growing the awareness and interest in video phone service.

The Four Compromises with Internet Video

Video is massively bandwidth hungry.  Full uncompressed video would require about 221 Mbps of bandwidth (4,000 times more bandwidth than is available on a 56kbps dialup line!).  Probably none of us have sufficient bandwidth for full broadcast quality video, so it becomes necessary to compromise between the quality/video experience you'd like and the bandwidth available to you.

You'll need to juggle three aspects of the video you send to balance against the fourth compromise - the bandwidth available to you.  If you want the best in one of these categories, you'll have to trade-off by accepting poorer settings in other categories.

Note that not all these variables can be adjusted.  And, depending on the camera and video software you are using, some adjustments may be done using the camera software, and other adjustments might be made through the video software.

Picture size

The bigger the picture size, the more bandwidth your video will take.  Normal television pictures have a resolution of 720x486 pixels (and to make things more complicated, the pixels aren't exactly square).  A comparable computer resolution would be 640x480 square pixels.

Chances are your computer screen has a resolution of 800x600 or larger, meaning that even 'full resolution' television shouldn't take up the entire screen.

Webcams typically are theoretically capable of this resolution, and of several smaller resolutions, too, of which the most common is 'quarter frame' - 160 x 120 pixels (also called QVGA).  Note that quarter frame is actually only one sixteenth the total number of pixels.  In other words, a smaller size can make a big saving in the amount of bandwidth you need.  A similar size is 176x144.

Most people seem content to use picture sizes between quarter frame and half frame for their webcams.  For general person to person talking, this gives plenty of picture of the other person's head and shoulders.

Picture quality

The biggest saving in bandwidth is made by compressing the picture information that is transmitted.  The higher the picture quality (the sharper and clearer it is) the more bandwidth your video will take.  Blocky and blurry video has been more highly compressed than fine clear video.

The difference in bandwidth between 'okay' quality and visibly poor quality is about a factor of two.  Good quality video requires about twice as much bandwidth as poor quality.  And very poor quality video will use even less - perhaps one third the amount of good quality video.

On the other extreme, to go from 'good' to 'great' quality video will require an increase of about four times in bandwidth.

So tune your picture quality to the lowest acceptable, but you don't need to go lower than that, because the bandwidth saving starts to be dwarfed by the loss of quality.

Refresh speed

Normal television and movie pictures have 24 or 30 images every second.  This is sufficient for us to perceive smooth motion.  The fewer the number of images (called frames) per second, the more jerky the motion becomes.

Once your refresh rate goes below 10 frames per second, the jerkiness becomes increasingly obvious, and below about 3 fps you start to see a series of slowly changing images rather than experience any sensation of motion.

Bandwidth

How much bandwidth is needed to support acceptable video?  The answer is 'it depends'.  Obviously it depends on the settings for the three variables above.

The Yahoo video program has a helpful feature which shows you how much bandwidth the video feed you are sending or receiving is using.  These measurements are in kb/sec - kilobits/sec.  Most datalines are rated in kilobits or megabits per second, making it easy for you to match the bandwidth being used with the total bandwidth you have.

Yahoo reports that its video takes anywhere from less than 10kb/sec up to as much as 240 kb/sec.

Keep in mind you can't use all the rated bandwidth on your data line for video.  You're almost certainly using some bandwidth for your voice communication, plus you'll have other things communicating with the internet as well (for example, your mail program might be regularly checking for email and downloading new messages).

Plus, if you and the person you are communicating with are both sending video to the other person, then you'll be using twice as much bandwidth - half to send and half to receive.  Some datalines have separate bandwidth for sending and receiving channels, other types of dataline have total bandwidth for both sending and receiving, and some datalines have much more download bandwidth (ie for receiving video) than they do for uploading (ie sending bandwidth).

In calculating your video bandwidth requirements, don't forget also that the limiting factor will be who has the slower internet connection - you or the person you're sharing video with.  Or, perhaps you both have extremely fast internet connections, but maybe there is a bottleneck somewhere else on the internet between the two of you.  This can particularly be the case if you are in two different countries; there might be plenty of internet bandwidth within each country, but sometimes there can be bottlenecks on the international circuits between the countries.

One more comment about bandwidth - if you're not sure what your dataline is actually capable of giving you in the form of real world bandwidth, then you should use this site to test your speed.  The results might surprise you.

Best Strategy for Compromising your Settings

If bandwidth isn't an issue, go for as high a quality, large picture and high refresh rate as you and the other person/people can support.

But if bandwidth is a problem - either at your end, or at the other person's end, then cut back first on picture size down to a minimum acceptable size for your purpose, then slow down refresh rate to 5-10 frames per second, then trim quality back to where you start to see visible degradation in picture quality.

If that still uses too much bandwidth, slow down the refresh rate some more, and then perhaps drop the picture quality a bit more.

If that still doesn't work, then - alas - there simply isn't enough bandwidth for video.

The importance of the camera

There are many different webcams available for sale, ranging in price from as low as $20 and up to $100 or more.  There's commonly available in computer stores, and (as with many other things) Amazon has an extensive range and at good prices.

In most cases, even the $20 webcam is going to have greater capabilities than most of the free video communication programs can handle.

Most cameras use a USB connection.  USB cables should be no longer than about 15' for best performance, but hopefully this doesn't restrict your ability to conveniently position the camera.

And, talking about positioning, a flexible tilt/swivel mounting base is a great help when trying to work out where to put the camera and how to mount it in its place.

True or Interpolated Resolution

One thing to be careful of, when reading camera specs, is whether the resolution being quoted is the true resolution or an interpolated resolution.  An interpolated resolution is a meaningless measure - it is what happens when the camera's base resolution is artificially boosted by simply inserting extra pixels that have artificial data sort of midway between the real pixels.  It gives you no more resolution or clarity, it just makes for a bigger picture and more bandwidth, but with no more picture quality.  Be sure to always compare true resolution data, not interpolated resolution data.

Field of View/Focal Length

A seldom quoted measure is the camera's focal length or field of view (the two being related - the shorter the focal length, the more 'wide angle' it becomes and the greater the field of view).

If your camera will be close to you, then a wide field of view is a good thing to have, so you will be able to get your entire head and shoulders into the image.  If the camera will be further away, then a narrower field of view (and longer focal length) would be better.

A common problem with cameras that have very wide fields of view is that you get a distorted image - a 'pin cushion' or 'fish eye' effect, such that the middle of the sides push out, and square shapes become more like circles.

Normal fields of view seem to range from about 42 degrees up to about 55 degrees.  Wide angle cameras can go up to almost 80 degrees.

Refresh Rates/Frame per Second

Have a look at camera refresh rates if you will be using your camera within a LAN environment (where bandwidth isn't a problem).  Some cameras can't give a full 30 fps when sending large (ie 640x480 size) images.  But if your usage will be mainly over the internet, you're unlikely to ever have enough bandwidth to allow for 30 fps at 640x480 resolution.

Manual or Fixed Focus

Because webcams have a short focal length and small aperture, it is often acceptable for them to be fixed focus.

Better quality webcams will have a manual focus ring on them.  If you get a webcam with manual focus, be sure to remember to adjust this from time to time if you change the distance between the webcam and whatever it is viewing (eg yourself).

Adjustments

Unlike a regular film camera, most of the adjustments in a webcam (or any other digital camera) are electronic rather than physical.

This means the flexibility of the camera is usually determined by the driver software that comes with it, and so obviously this can be almost as important as the camera itself.

If you can adjust the 'white balance' of the camera, and if you can adjust the brightness and contrast, then you'll have more control over your image quality than if these are all done automatically (or not at all).

Camera positioning and lighting

The camera is best positioned if it is looking straight at you, and you looking straight at it.

This means the camera should be very close to the side of your screen.  It is best to not have the camera looking up at an angle at you, or down from an angle, because this creates an image different from what people would see when looking at you normally.

I also put the windows for conferencing on the same side of my monitor as the camera is, so when I'm looking at the windows on the computer, it appears as though I'm looking more closely at the camera than if the windows were on the far side of the computer screen.  This also reduces the 'shifty eye' effect which can sometimes be quite noticeable, being caused when you swap focus between the camera and the screen.

Cameras generally work better in moderately bright even lighting conditions.  Ideally, you should have soft white light falling on your face, and you want to avoid extremes of light and shade in the picture (including whatever is in the background).

Generally a diffuse light is better than a single spot light - it reduces the harshness of shadows in the picture.

Try not to have any lights that shine directly into the camera.  This can upset the camera's auto exposure.

Summary

Adding a video feed to your conversations is now easy and inexpensive.  A webcam costs about $30 or less, and the video sharing software is usually free and sometimes already pre-installed on your computer.

If you have a broadband internet connection, why not get even more use out of it by having video as well as voice conversations via the internet.

Read more about video over your internet line

The next part of this series tells you all you need to know about choosing the best (and free!) software to use with your webcam.

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Originally published 9 Sep 2005, last update 21 Jul 2020

You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.