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An Overview of MS Windows Media Screen Technology

Published: July 01, 2000
By Marcus Matthias, Microsoft Digital Media Division

Summary: This paper addresses the benefits of the new Windows Media Screen technology, highlights some common scenarios in which it can be used, and offers some best practices for creating content with it.

On This Page

Introduction Introduction
Usage Scenarios Usage Scenarios
Best Practices Best Practices
Recommended Configuration Recommended Configuration
Playback Considerations Playback Considerations
Conclusion Conclusion
For More Information For More Information

Introduction

One of the most anticipated features of the new Microsoft® Windows Media™ Technologies 7 platform is its screen-capture technology. This technology enables content owners and subject-matter experts to use an application such as Microsoft® Windows Media™ Encoder 7 (or tools from third parties that have licensed the Microsoft® Windows Media™ Format SDK) to capture content directly from a computer screen or file, compress that content, send it over a communications network (such as a phone line), and decompress it for viewing.

While compression technologies for camera video have progressed rapidly, compression of applications video, or video containing movement on the computer screen, hasn't progressed at the same rate. As a result, it has been virtually impossible to capture screen movement, compress it in a way that preserves quality, and distribute the compressed file over an intranet or the Internet. Consequently, companies have been forced to offer poor-quality content on the Web or distribute content by means of a CD-ROM. Microsoft® Windows Media™ Screen codec version 7.0 is specifically designed to address this problem.

Windows Media Screen codec offers perfect reproductions of computer screen images (such as mouse movement, dialog boxes, and drop-down menus) at data rates as low as 15 kilobits per second (Kbps) and at screen resolutions as high as 1024 x 768. Now, for the first time, high-quality content can be streamed over dial-up modems. In fact, files can be small enough to send through e–mail. For example, a 73-second screen capture video compressed at 22 Kbps can maintain a file size of 197 KB.

This paper covers the following topics:

  • Usage Scenarios. Discusses common applications of screen capture technology, including helpdesk support and software demonstrations.

  • Best Practices. Provides guidelines for achieving the best results using Windows Media Screen codec.

  • Recommended Configuration. Describes the optimal hardware configuration for using Windows Media Screen codec.

  • Playback Considerations. Explains how the Windows Media Screen codec is used with Microsoft® Windows Media™ Player.

  • Conclusion. Summarizes the benefits of using Windows Media Screen codec.

  • For More Information. Includes links to more information about creating content with Windows Media Screen codec and Windows Media Encoder.

Usage Scenarios

Screen capture can take place in one of two ways:

  1. You can capture content directly from the screen using Windows Media Encoder or from another application that supports Windows Media Format.

  2. You can convert content to Windows Media Format by using Windows Media Encoder from a file type such as .avi.

Some advantages of direct capture are that content is instantly ready for streamed distribution to viewers, and no additional software tools are necessary to create the Windows Media file. Some advantages of creating or converting from .avi format are that .avi files can be edited prior to being compressed into the Windows Media Format. The ability to convert files also means that legacy content can be compressed and reused as opposed to being recreated from scratch. Windows Media Encoder then uses the existing .avi, not the computer screen, as its content source.

Some of the most common applications of screen capture technology are electronic learning, helpdesk support, and software demonstrations. Potential deployment scenarios include:

  • Live presentations. Historically, it has been virtually impossible to stream live demonstration content and slides from seminars or conferences over an intranet or the Internet. In addition, content owners spend additional money on repurposing that content for the Web. Now you can capture and stream both demonstrations and slides in real time over an intranet or the Internet without any disruption to those attending the live event. You can also archive the content with negligible post-production efforts so users can access the content on demand.

  • Helpdesk support. Because Windows Media Player can synchronize with any browser object, a Web designer can create an environment where the Web application diagnostically determines what the user wants to see. Users can watch the content at their convenience. In this scenario, the content owner may want to edit the file before compressing it to add various features to the clip or to correct any mistakes made in the original screen capture. Once the edits are complete, the file is compressed and posted to a Web site.

  • On-demand software training. Companies can now show users how to use software applications, rather than relying on static text and screen shots. They can use the Windows Media Screen codec to create clips of various user activities or product functions, and integrate those clips into any Web page. In addition to providing an easy way to get product information to customers, the Windows Media Screen codec also offers significant value to sales personnel, who no longer must set up and maintain multiple applications.

Best Practices

You can improve the quality of content in a number of ways by using Windows Media Screen codec, starting with some fundamentals regarding the capture of any type of video.

  • Know the application for which you are designing. Will you be embedding Windows Media Player in a Web page? What is the size of the window in which your content will be displayed? For example, if you plan to use an 800 x 600 window, you'll want to capture your content at 800 x 600.

  • As with camera video, the quality of applications video degrades with excessive motion. When possible, avoid rapidly opening and closing windows.

  • If you plan to capture and compress data from a computer screen directly (as opposed to creating an .avi file) and plan to use audio, take steps to maximize audio quality. For example, use a high-quality microphone, and consider using a room designed to minimize background noise.

Windows Media Screen codec relies on sophisticated algorithms that process data in a unique way, achieving very high levels of compression for typical applications video. Nevertheless, the following screen capture activities are more difficult to compress and should be avoided or used only when additional bandwidth is available:

  • Dragging windows across the desktop. Dragging might result in dropped frames because this type of movement makes it impossible for the algorithms to have a consistent frame of reference to compute data. (If dragging windows is necessary, in Control Panel, in Display Properties, be sure to clear the Show window contents while dragging option.)

  • Scrolling down (or up) a Web page. Scrolling makes it difficult to maintain a consistent reference point, resulting in dropped frames. This underscores the importance of creating content at the appropriate resolution. (Using the PAGE UP or PAGE DOWN keys may be an acceptable alternative).

  • Displaying images containing great variation in color depth. It is difficult to compress an image where there is significant variation in color from one pixel to the next. The result could be dropped frames of data.

  • Using Windows Media Screen codec to capture a screen that includes a window in which camera video is playing. Compression of camera video and compression of applications video are two very distinct techniques. Using Windows Media Screen codec to compress camera video can result in suboptimal results. You should use a video codec, such as Microsoft Windows Media Video codec 7, to compress camera video.

Recommended Configuration

When considering hardware requirements to create content, remember that Windows Media Encoder is a CPU-intensive application. For the best results, use the fastest processor you can obtain or use a computer with multiple processors. You'll also get the best performance out of Windows Media Encoder by using an operating system that runs applications, not services, in the foreground.

Table 1 Component Configuration

Component

Optimal configuration

Recommended configuration

Minimum configuration

Operating system

Microsoft® Windows® 2000 Professional

Windows 2000 Professional

Microsoft Windows 98

Processor

Dual Pentium III, 733 megahertz (MHz)

Pentium III, 500 MHz

Pentium II, 450 MHz

Memory

256 MB

128 MB

64 MB

Free hard disk space

500 MB for content creation and editing

5 MB for Windows Media Tools; enough free hard disk space for content creation and editing

5 MB for Windows Media Tools

Playback Considerations

Windows Media Screen codec is included with Windows Media Player 7, and users of earlier versions of Windows Media Player will automatically receive Windows Media Screen codec the first time they access content that was created with it. User intervention is not necessary. The automatic codec download mechanism means that users don't need to install a new Windows Media Player every time a new codec is developed. As a result, Information Technology (IT) support costs are reduced and users enjoy a better multimedia experience.

Conclusion

Windows Media Screen codec offers long-awaited functionality to easily deliver training, helpdesk support, and software demonstrations to all users, including those on dial-up connections. And it does so with exceptional quality. Users do not need to know what the codec is or how it works. By using Windows Media Screen codec, content owners can now easily configure Windows Media Encoder to compress data from a screen or existing file.

For More Information

Windows Media Screen codec is installed with Windows Media Encoder 7 and will be available through many third-party applications. You can download Windows Media Encoder from the Windows Media product site ( http://www.microsoft.com/windows/windowsmedia/forpros/encoder/default.mspx ).

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