What Is Streaming Media? To understand the role of streaming media, one needs to understand the functioning of the World Wide Web. Web servers are often described as "stateless." What that basically means is that the web server takes a request for information, pushes that information out the door as fast as it can, completes the transaction, disconnects and goes on to other requests by other users. On the client side, your Web browser takes the information it receives, assembles it on the screen, and then ignores the Web server until you click on a link. This stateless approach works very well for media like graphics and text. Feed them into the browser and simply slap them on the screen. However, moving images and sound are problematic. Unlike a graphic, video, animation and sound have a time element to them. With the time dimension, often comes a larger file size. Under the stateless approach, a Web user would need to download the entire video clip before it can be viewed and with the large file size that comes with even a short video clip, the wait becomes unbearable.

With streaming media, the goal is to bypass the limitations of the World Wide Web. So, rather than a stateless data connection, streaming media is more of a continuous connection. There is a commitment there. Much like TV or listening to the radio, you receive the images or audio just before you see or hear them. Spaced out over time, the file size of the clip becomes less of an issue. The reality is that raw file sizes for digital audio and video are absolutely huge. So, to get them down to a size that works for a modem or LAN, compression is used. The goal of streaming compression is to throw away data that you don’t need. That makes the file size much smaller. Streaming audio also makes it possible to broadcast live or pre-recorded music over the Internet on a continuous basis. Internet "radio stations" can broadcast to a worldwide audience.

Prior to streaming, a typical video file (*.avi) was completely downloaded from the Internet before it could be played. With streaming, only the first few seconds are downloaded (buffered) before the video begins to play. As the streaming file is being viewed, it is also downloading in the background.

Basic Concepts

Encoding
In the case of streaming media, encoding refers to the compression of media files into a streaming format. Encoding is the process whereby media files are prepared for streaming over the Internet.

On-demand encoding
Encoding from a file is as easy as pointing to the source file, setting a name for the destination file, picking audio and video codecs, choosing the bit rate, and clicking start. Most encoding software carry built-in wizard templates to make the job even easier; simply pick the template describing the target audience and the codecs and bit rates are automatically defined.

Live encoding
Live encoding is a little trickier than on-demand because the input to the encoder comes from audio and video capture cards within the encoding computer.

Codec (compression/decompression)
Codecs are mathematical algorithms that allow media files to squeeze into a smaller streaming format for decoding by the end-user’s player. Encoding software uses codecs for compressing the file while decompression occurs during the viewing process on the end user’s computer. The process is similar to zipping and unzipping a file on a PC. Standard encoding software such as Microsoft Encoder and Real Publisher encode locally stored content as well as live feeds and inputs.

Multibitrate Codecs
Multibitrate codecs allow several streams of different bit rates to be bundled into one file. The streaming server then communicates with the end user’s media player to determine the optimum speed for delivery.