The term streaming refers to the technology of broadcasting audio and video files over a network. Because of the often very large size of audio and video files even after compression, streaming technology allows end users to begin experiencing the audio or video files while the files are still downloading. In this way, very large files can be served over a network. Streaming media can generally be served over a network in two different ways: realtime (live) or progressive (on-demand) streaming. Realtime streaming is often used in the live webcasting of events or continuous services such as Internet radio. Realtime streaming uses a dedicated webserver to deliver the media and a protocol intended only for streaming media called RTSP (Realtime Streaming Protocol). Because the webserver is dedicated to the streaming of media, the streams can be adjusted to suit the connection speed of the end user, resulting in a playback with fewer pauses and glitches. Progressive streaming, also known as progrssive download, is a simpler method that does not require a dedicated server. The files are sent over the network and a media player with streaming capabilities on the user's machine starts playing the file while it is downloading.

Generally, progressive streaming is appropriate for short clips. If the clips are of high quality, this may result in a longer wait for the user, but the quality will not be adjusted by a streaming server. For longer clips such as lectures, presentations and movies, realtime streaming is better choice. Progressive streaming also has the benefit of working on any HTTP webserver, making the files much easier to administer.

There are generally three popular formats for the streaming of audio and video files: Quicktime, RealMedia, and Windows Media. The differences in quality and speed are only very slight. Your decision of which format to use should be based on the anticipated users of your files. Each of these media formats are playable only on the accompanying media player.Quicktime is an Apple product, while Windows Media is a Microsoft product. RealMedia is independent of the two but is often critisized for containing too many advertisements and for being an annoyance once installed. All three players are available for both the Mac and PC platforms, and all three players are free.

All three of these formats use basically the same process for progressively streaming the files. After the media files are created , compressed and put on a webserver, a reference file (or playlist file) is created that point to the actual location of the media file. This reference file is the file that is linked to from a webpage and that tells the appropriate media player to process the file as a stream. The first step is to create your media files. There is a huge variety of software packages available for the creation of media clips, such as Final Cut Pro, iMovie, as well as many free audio recording tools. Second, the files must be compressed and encoded in the format and level of compression you choose. This can be accomplished using Discreet's Cleaner software, Quicktime Media Player, or Real (Helix) Producer, just to name a few. Finally, the media file must be uploaded to a fileserver.

Progressive Streaming of Audio and Video with Quicktime

1. Open the Quicktime Player or Quicktime Pro application.
2. Under the File menu, select Open URL....
3. Enter the complete URL for your media file, including the prefix http://. Remember also that Quicktime files have a .mov file extension. Click OK.
4. After the media clip starts playing, stop it by clicking the Pause button in the center of the player and rewind the play head to the beginning of the clip either by dragging the playhead or by clicking the small rewind button
5. Return to the File menu and select Save As...
6. Save the file in a place where you will later be able to find it. You may rename the file if you like. The resulting file is called a reference file. It is a small file that serves as a pointer to the auctual media file. This reference file may be uploaded to a webserver and linked to just like any other type of file. Linking to this type of file however, will cause the Quicktime player to open on the users computer and for the progressive streaming of the media file to begin.

Progressive Streaming of Video with RealPlayer

1. If you are using a PC with Windows, open the Notepad application. This application is usually found under the Accessories part of the Start menu. On a Mac, open SimpleText.
2. In a new, blank document in either Notepad or Simpletext, type the complete URL of the media file you uploaded to the webserver on the first line. It is often easier to find the file with an Internet browser such as Internet Explorer or Netscape Navigator and then to copy and paste the URL. Remember that RealMedia files have a .rm file extension. If you have several media clips encoded with RealMedia, you can list them (separated by line returns), and they will play consecutively.
3. Save this file by going to the File menu and selecting Save As... You may give the file any name you wish, but it must have .ram as its extension. Double clicking this file cion on your local computer should open the REalPlayer application and start playing the clip. This .ram file serves as a pointer to the actual file and is the file you would link to from a webpage. Upload this file just as you would an .html file.

Progressive Streaming of Video with Windows Media

1. Open the Windows Media Player application.
2. Under the File menu, select Open URL....
3. Enter the complete URL for your media file, including the preceeding http://. Remember also that Windows Media files usually have a .wma file extension. Click OK.
4. After the media clip starts playing, stop it by clicking the pause button in the bottom of the player.
5. Return to the File menu and select Export Playlist to File..
6. Save the file in a place where you will later be able to find it. You may rename the file if you like. The resulting file is called a playlist file (.asx extension). It is a small file that serves as a pointer to the auctual media file. This playlist file may be uploaded to a webserver and linked to just like any other type of file. Linking to this type of file will cause the Windows Media player to open and for the progressive streaming of the media file to begin.

Links
If you would like to learn more about the techniques involved with streaming media, please visit one of the following sites:
Webmonkey - Streaming Video for the Masses
Streaming Media World

Streaming Media Players
The following players are capable of playing both audio and video files including the recently popular MPEG-4 standard.
RealPlayer / RealOne
Quicktime player
Windows Media Player