Windows Media Services enables streaming of multimedia content over all types of networks. These networks can range from low-bandwidth, dial-up Internet connections to high-bandwidth local area networks. Windows Media Services (called “Streaming Media Services”) is a server role installed from the Server Manager:
- Click Start | Server Manager. In the server tree on the left, click Roles.
- Under Roles Summary in the right pane, click Add Roles and click Next.
- In the list of roles, click Streaming Media Services and click Next. Read the Introduction To Streaming Media Services and click Next.
- If you think you will want them, click Web-Based Administration and Logging Agent. If you are asked if you want to add the features required for Web-Based Administration or Logging Agent, click Add Required Role Services and click Next.
- You are asked if you want to use Real Time Streaming Protocol (RTSP) or Hypertext Transfer Protocol (HTTP), but HTTP is grayed out since port 80 is being used for normal (nonstreaming) HTTP connections. Click Next three times (because you are also installing some additional features of IIS) and click Install.
- When you are told that the installation is successful, click Close.
NOTE: Streaming audio and video allows the media to be played on the receiving computer as it is being downloaded, instead of waiting for it to completely download before playing it. The Microsoft Windows Media Player, included in Windows XP and Vista, can be used to play streaming audio and video.
Utilizing Windows Media Services, a media server can stream audio and video content over the Web. To understand why this is significant, it helps to understand the way a typical HTTP session works. First, a web browser sends out a request for a URL over the network. The web server hosting the URL responds to the request and downloads the appropriate information to the browser. Once the web pages are downloaded from the site, the browser displays them.
When the user clicks another link, the browser requests another URL and the server responds. This works great for small file sizes, such as a web page, but video and audio files are so large that waiting for files to download in this way is like waiting for paint to dry. Windows Media Services uses streaming technology to enable you to load and play the audio or video while it is still downloading. This greatly increases the satisfaction of the user who is downloading the file.
Stream Methods
There are two ways to stream audio and video. One uses a web server alone; the other separates the web tasks from the streaming media tasks. The second method utilizes a streaming media server to stream audio or video, in conjunction with a web server used to download the rest of the web information.
Stream with a Web Server The server sends the audio and video files in the same fashion as it would send any type of file. The streaming client stores, or buffers, a small amount of the audio or video stream and then starts playing it while continuing the download.
Buffering theoretically allows the media to continue playing uninterruptedly during periods of network congestion. In fact, it is normal for it to get interrupted on a dialup or other lower-speed connection. The client retrieves data as fast as the web server, network, and client connection allow.
Stream with a Media Server With a media server, the first step is to compress the media file and copy it to a specialized streaming media server (such as Microsoft’s Windows Media Services). Next, a reference is made on the web page so that IIS knows when and where to retrieve the streaming data for the page. Then data is sent to the client such that
the content is delivered at the same rate as the compressed audio and video streams. The
server and the client stay in close touch during the delivery process, and the streaming media server can respond to any feedback from the client.
Stream with Windows Media Services Designed specifically for the task of delivering live or on-demand streaming media rather than many small HTML and image files, a Windows Media Services server offers many advantages over standard web servers:
- More efficient network throughput
- Better audio and video quality to the user
- Support for advanced features
- Cost-effective scalability to a large number of users
- Protection of content copyright
- Multiple delivery options
Windows Media Services, diagrammatically shown in Figure above, automatically switches to the appropriate protocol, so no client-side configuration is necessary.
