It took thousands of years for communication technology to progress from Mesopotamian cuneiform to the printing press, and a few hundred more-through 19th century innovations like telephony and motion pictures-to achieve today's media cornucopia. A similar evolution has been underway on the Internet, though obviously at a somewhat accelerated pace. At the birth of the Mosaic browser, the World Wide Web was a static, silent place. But the introduction of the RealAudio system for streaming sound files followed soon thereafter, and five years later, streaming media is a wanna-be mega-industry, with its own trade shows and magazines.
For information professionals, the significance of streaming proceeds from the well-worn cliché that a picture is worth a thousand words. There's no denying that human beings respond differently to visual and auditory stimulation than to simple text. Further, a presentation that is temporal and dynamic can often grab our attention in ways that static text and images can't. That doesn't mean that still pictures and the written word have lost their value as technology has expanded and transformed our communication tools. But it does mean that an information strategy that is exclusively alphanumeric in orientation may be missing a lot of opportunities. Today's information consumers-at work and at home-are ready for a multisensory approach in which messaging and learning are enhanced with animation, video, and sound.
Like any medium in its early days, the technology of streaming is uneven, and the overall state of the field is chaotic. It's likely, however, that issues such as bandwidth and incompatible standards will work themselves out in the long run. Does it make sense to steer clear in the meantime? Not if you're working with information that can be explained or reinforced with audio-visual media. For the same reasons that companies use tools such as videotape, CD-ROMs, LaserDiscs, and DVD, streaming has a role to play in today's content-delivery mix. And, of course, the fact that streaming enables delivery over networks makes it difficult to ignore. With realistic expectations, and a clear understanding of the challenges involved, streaming already has much to offer those whose job is to inform or persuade.
Streaming is often thought of as any client-side playback of time-based media that originates on a server. A more precise definition, however, takes into account the distinction between true streaming and the playback of downloaded files. Before streaming, the only way to experience posted media files was to download them in their entirety to your local hard drive before playing. That's generally not a problem for synthetically generated media such as Flash animations or MIDI music, either of which can download quickly even over a dial-up connection. But in the case of audio and particularly video (which tends toward very large file sizes), the lack of near-immediate response becomes a huge limitation.
Streaming addresses this problem by establishing a steady flow of media data from the server to the client, allowing viewing (or listening) to begin seconds after the stream is requested. The two main categories of streaming are "live" (Webcasting) and "on-demand."
While streaming media systems vary, the typical chain of events begins with an HTML page in a browser. When the user clicks a link for a media file, the browser sends a request to the server. The server sends back a small metadata file that contains information about the location and format of the requested file. The browser then launches a "plug-in" or software player that can play back media in that file format.
Once the player is launched, the browser passes it to the location of the requested media file. The player allocates a storage buffer and opens communication with the server on which the file is stored. The server streams the media to the player, which stores it in the buffer. As the buffer starts to fill, the player begins playing the streamed content out of the buffer. As long as the bitrate of the stream into the buffer exceeds the rate at which the media is played out, you've got streaming.
In addition to the advantage of near-instant response to the user's request-a key element for viable interactivity-streaming is also attractive from the standpoint of maintaining control over dissemi- nation of one's content. Depending on the player software, old data may be overwritten by new data as it is recorded into the buffer, meaning that a complete copy of the file need never be present on the client hard drive. That allows the content owner to restrict access to the content to those who are connected to the server at any given moment.