Windows Media Technologies
Microsoft Windows Media Technologies support to create, deliver, and play streaming media files for applications ranging from news and entertainment to e-commerce and corporate training. Windows Media Technologies components include the Windows Media Tools, Windows Media Services streaming server, and Windows Media Player. These provide an end-to-end solution for streaming multimedia, from content authoring to delivery to playback.
Microsoft Windows Media Technologies is distributed as part of the Microsoft Windows 2000 operating system. It allows you to create, distribute, and play streaming media files
(Figure 1: Components of Windows Media Technologies transmission)
Windows Media Technologies use an application-level protocol called Microsoft Media Server (MMS) to send Active Streaming Format (ASF) files across the Internet and intranet. A URL that points to a streaming ASF file includes MMS as its protocol,
The MMS protocol automatically looks for the optimal transport to stream media, in the following order:
- UDP (User Datagram Protocol)
- TCP (Transmission Control Protocol)
- HTTP (Hypertext Transfer Protocol)
Streaming is the term used for media files that, unlike conventional files that must download in their entirety, begin playing while they are being transmitted to the player. Why is streaming important? Time. With Windows Media Technologies, content authors can create, deliver, and play streaming media files in the Advanced Streaming Format (ASF). ASF files solve the problem of long download times by starting playback almost immediately, while the data is being sent. As the name streaming suggests, ASF files flow like a stream. Rather than picking up and sending a whole reservoir of data at once, ASF files send the first part of an audio or video clip down the "pipe" first. While that is playing, the rest of the data flows down, arriving in time to be played. To make sure playback isn't interrupted if logjams slow the network, the player collects a small backlog of data, called a buffer, before it starts playing. If the data keeps flowing fast enough, playback is continuous. Users only have to wait the few seconds it takes to create this buffer before viewing the file, regardless of whether the file lasts 30 seconds or 30 minutes.
Windows Media Technologies can stream both live and on-demand (stored) content. On-demand content can be streamed from either a Web server or a Windows Media Services server, though the latter provides more flexibility and better performance. And Windows Media Services performs both standard unicast streaming (delivering live or on-demand content to thousands of users) and bandwidth-conserving multicast streaming (sending a single stream of real-time content to an unlimited number of users).
Windows Media Technologies also give content authors the ability to embed the Windows Media Player in a Web page. To make streaming media files interactive and to create rich multimedia presentations, authors can add script commands to open Web pages in adjoining browser frames or place text captions in the player screen, all synchronized with the ASF content.
The Windows Media Technologies 4.0 opens up a whole new realm of possibility for generating revenue and for business solutions. With FM-stereo quality audio at Internet connection speeds, customers are willing to pay to view and listen. Companies are taking advantage of two new features--the improved content piracy protection in the new Windows Media Rights Manager, and an easy-to-use wizard that sets up viable pay-per-view applications. Other companies are adding audio or video to their online training or Web-based communications applications, making the delivery of the information more effective.
Streaming Media with Windows Media Technologies
There are three basic steps to delivering ASF files: create, serve and play. The Windows Media Technologies provide the tools and platforms necessary for all three tasks.
1. Creating Streaming
The content creation components of Windows Media Technologies include tools for authoring both live and on-demand content, and for converting other file formats such as WAV, AVI, MPEG and MP3 to ASF.
The Windows Media Encoder creates live content for broadcast over the Internet or intranets. Content authors can encode live audio and video feeds and then add them to dynamic mixtures of other media. The tool synchronizes and compresses the media components into a single file, augments the file with error-correction information, and delivers it to a Windows Media Services server, which then transmits it over a network. The Windows Media Encoder can also encode stored content for on-demand playback.
The other Windows Media Tools provide simple ASF authoring tools for creating or editing on-demand content. The tools include the Windows Media On-Demand Producer, Windows Media Author, Windows Media Plug-in for Adobe Premiere, and the command-line utilities VidToAsf, WavToAsf, and PublishToAsf. In addition to the growing number of Windows Media content creation tools, there are also an increasing number of third-party tools that output .asf files.
2. Hosting and Delivering Streaming Media
To host an ASF file for streamed delivery, you simply place the compressed ASF file on a Windows Media Services server and link to this file on a Web server.
The Windows Media server components are a set of services running on Windows NT Server that can unicast and multicast audio, video, and other media to client computers. To deliver live, real-time content, the server works in conjunction with the Windows Media Encoder, which compresses the audio and video feed in real time and passes it to the Windows Media server for delivery to the network. On-demand ASF files must be stored on a server's hard drive and passed to the network by the Windows Media Services server.
Windows Media Services offer the widest range of bandwidth, delivering live broadcasts or streaming stored multimedia content from as low as 3 Kbps audio to 6 Mbps of audio and video. Windows Media Services can scale to meet the heaviest demands; a single server can scale to support over 3000 simultaneous user connections, letting you host large Internet broadcasts easily and cost-effectively. And Windows Media Services automatically ensure top performance over the network for the smoothest video and richest audio experience to every end user.
3. Playing Streaming Media
Users play ASF content with the Windows Media Player. Intranet and Internet surfers can use the player to play audio, illustrated audio (synchronized sound and still images), and full-motion video files, plus RealAudio and RealVideo 4.0 (and earlier) content, as well as to offer playback of many other multimedia data types. With the advanced content compression technologies in Windows Media Technologies 4.0, Windows Media Player delivers superb audio and video quality at standard 28.8 kilobit per second (Kbps) Internet connections.