Video on the Internet is displayed differently than both film and analog television. Internet video is really just digital data. When you download a video from YouTube, you are not downloading a video, you are downloading digital code that needs special software to decode it and display it as a video. This software could be Windows Media Player, RealPlayer, or Adobe Flash Player.
To put this into perspective, everything in your computer is digital data. What you write in a text document is saved on your hard drive as digital code, not as a document of text. When you open it in a software program, the program decodes the digital data and turns it into text. This happens with images, too.
Not all types of files are equal when it comes to size—text usually requires very little data to record information. But images, audio, and video are made up of much more data. You can see how large image files are when you surf the web. On a webpage, you’ll notice that the text downloads faster than pictures. You’ll usually see the text immediately but have to wait a few seconds for the images to appear, because pictures require more data than text and take longer to download. The reason for this delay comes down to competition between bandwidth and file size.
Trade-off between bandwidth and file size
Bandwidth is the measurement of how fast data can travel along a connection. It’s measured in terms of how many bits of data can travel across the connection between you and the Internet per second. Bandwidth is often categorized as either narrowband or broadband. Narrowband simply means narrow bandwidth and broadband means wide bandwidth.
There’s no sense putting an actual figure on what constitutes broadband because the figure continues to evolve. When I led workshops about the Internet to broadcasters in Britain in 1999, a bandwidth of 512 kilobits per second was considered broadband. Today, 10 megabits (10,000 kilobits) per second is considered broadband. Next week it may be 20 megabits—all we know is that the capacity will continue to increase.
Bandwidth will affect how easily your viewers access your video. If they have broadband, they should be able to watch video. If not, your video will not download in real time, and may stop and start as they watch it. Because of the restrictions of bandwidth, we are not able to download true high-quality video. Most of it is highly compressed so that the file requires less data.
Bandwidth is a huge issue facing corporations because their connections to the Internet are almost always shared among purposes. And given that video is generally large in file size, you need more bandwidth. If you’re in a retail organization and want to make learning video available to all of your stores, you will be competing for bandwidth at each retail location with connections to banks and credit card merchant services. If you’re in an office environment, you’ll be competing for bandwidth with other workers who are sending holiday photos and email jokes.
File size creates big problems for video on the web. If you have 25 frames per second, then for every 10 seconds of video, you are downloading the equivalent of 250 images—that’s a lot of data. There’s not a lot you can do about bandwidth, especially if you’re sharing your Internet connection with a whole office. But you can take one step to reduce file size, and that’s known as compression.
Basically, our aim is to reduce the amount of data required to display a video. The less data we use, the smaller the file size. The process of compression achieves this by doing two things: First, it will adjust pixels in the picture, and second, it will compress movement. Let’s quickly consider both in nontechnical terms.
Adjusting the pixels
Every individual frame is made up of many square dots called pixels. In high-quality images, each pixel may have a different color value. Often your image will have minor variants in color that are largely unrecognizable to the naked eye. By averaging these out, you can reduce the amount of data needed. The key here, of course, is to only change the differences that are unlikely to be noticed by the eye.
The second way to compress video is to record only the changes that take place between frames. Consider, for example, a video of a baseball player running to home plate. The only thing that changes in this image is where the baseball player is—the green grass and red dirt around home plate remain the same. Instead of recording four or five different frames, we can record a reference frame and then only the data that actually changes in relation to the reference frame.
When we compress video, these are the two things we are doing. Depending on the settings we use when we export our video, we can emphasize one more than the other. The key is to only compress the video as much as we need in order to reduce file size and still maintain quality.
There are two times when you will compress video. The first is when you export the master copy from your video editing software. You will be offered a range of options, and you need to discuss these with your IT administrator. The second time to compress video is after, when you have the option to take a high-quality video and run it through a file format conversion program, such as Format Factory. It will offer you options for the rate of compression, which will often be described in terms of the bandwidth on which you want your video to easily display.
Future of video
This all seems complex to a new videographer, and it sounds like you have to compromise on quality when streaming video over the web. If you’re worried, don’t be—the good news is that bandwidth continues to grow. This is due to new technology, including fiber-optic cable, which can carry incredible amounts of data per second.
If you consider the quality of video today compared to 10 years ago, you will have seen video evolve from blurry, smudged images that were the size of a postage stamp into remarkably clear video that can fill up your entire screen. It will only get better. But in the meantime, we need to compress our videos. Besides file size compression on the computer, there are a number of things you can do when shooting your video that will help to keep file sizes small.
This article is excerpted from Rapid Video Development for Trainers: How to Create Learning Videos Fast and Affordably (ASTD 2012). Rapid Video Development for Trainers meets the needs of companies and individuals who are thinking about or have dabbled in video production. Although producing focused, high quality video is well within the capability of nearly every development professional, the skill sets required to do so have not traditionally fallen within most trainers’ job descriptions.