Audio/Video on the Internet

The newspapers are full of stories about getting music and video over the Internet. These stories are full of confusing acronyms and jargon about formats and players and so on. Here is a quick primer.

Everything transferred from one computer to another–via the Internet or any other way–is reduced to a common denominator of “information,” meaning bits and bytes of data. This includes text, still images, audio, and video. Audio and video are more complicated than text and still images, and therefore they require more bits and bytes. Until now, this limited the use of video and audio on the Internet. But that is beginning to change for several reasons, including standardization, compression, and growing bandwidth.

Format: Audio and video files, like any other computer files, can be stored in different formats. A song or politician’s sound clip, for instance, can be an .au, .mp3, or .ra file, among others. Each format encodes the same audio information as a different pattern of bits and bytes and each is the baby of a different company. Likewise, video (and accompanying sound) can be a .mov, .asf, or .avi file, among others. The newest formats are .ram, being pushed by Real Networks, and .asf, being pushed by Microsoft. Each company sells software for creating audio/video files in its favored format. Then there’s the hot audio format .mp3, which isn’t owned by any one company, meaning that anyone may write software for it.

Player: To play formatted audio and video files, your computer needs a specialized bit of software called a “player.” In the old days, you had to download a different player for each audio or video format. Today’s players can each handle almost all the leading formats. In other words, you need only install one player, which can play almost any video or audio file. Current versions of the leading software—-Real Networks’ RealPlayer and Microsoft’s Windows Media Player–may be downloaded for free, here and here.

Compression: A full-length music CD contains around 70 minutes of music. That is about 640 MB of information in the format that your CD player uses (known as “raw“). But the newer formats used on the Internet compress that same music into fewer megabytes. For example MP3 can store that CD full of music as only 50 MB of compressed data–around one-twelfth of the uncompressed amount. (The program that turns ordinary sound files into compressed files is called a “ripper.”) Transferring a 640-MB file–70 minutes of music–using an ordinary 28.8 modem would take around 48 hours, whereas transferring the same music as an MP3 file takes only four hours. And it requires only a few minutes to download a single song. Once you’ve received an MP3 music file, you can play it on your computer using a player, use special software to put it on a CD (if you have a CD writer), or transfer it to a specialized Walkman-like device that can be used with headphones or in the car. Restoring the raw (uncompressed) file happens automatically.

Video vs. Audio: Video files are considerably larger than audio files, since they contain not only sound but also bits and bytes that tell your computer how to color each of thousands of constantly changing pixels. Even with compression, video of more than about five minutes is still too big for widespread use on the Internet. But as the Internet’s data-carrying capacity–“bandwidth”–increases, it’s likely that movies and TV programs will eventually be distributed this way.

Streaming: Older formats required you to download the entire file before playing it. Newer formats allow you to begin playing the file before the entire thing has been downloaded. Many of the sound and video clips found on Web sites today (including in Slate) are purposely of lower quality–the sound scratchy, the movements jerky–in order to download faster. With less information being transferred, they can “stream”: that is, a minute of sound and or images takes no more than a minute to download and you can listen to and/or watch without waiting or storing the data. Increasing bandwidth will eventually make this compromise obsolete.

Copy Protection: Technologies like MP3 allow ordinary folks to send songs from their CD collections to friends via e-mail, or to post them on Web sites. Many new artists, and a few established ones, have even built Web sites where they give away their music to build a fan base. Naturally, music labels are afraid all this will cut into their sales. They are pushing for formats that allow only a single user to listen to an audio file. Until this month, the five largest music companies had agreed not to offer music on the Internet until they’d all agreed on a format that protects their interests. But recently Sony has agreed to offer music using Microsoft’s copy-protection format, and Universal will offer music using a copy-protection format licensed from a third-party.