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Creating High-Quality Content with MS Windows Media Encoder 7

Published: July 01, 2000
By Tricia Gill and Rich Saunders, Microsoft Digital Media Division

Summary: This document is a brief tutorial on how to use the new features in Windows Media Encoder 7 to create high-quality video content from television, film, and screen sources. This article assumes that you have a basic understanding of streaming, compression, and audio/video production. (6 printed pages)

On This Page

Introduction Introduction
Capturing and Encoding Screen Content Capturing and Encoding Screen Content
Using Video Optimization Filters Using Video Optimization Filters
Encoding High-Motion Content at 60 FPS Encoding High-Motion Content at 60 FPS
For More Information For More Information

Introduction

Microsoft® Windows Media™ Encoder 7 is a powerful, easy-to-use, production tool that enables content developers to convert both live and prerecorded audio, video, and computer screen images to Microsoft® Windows Media™-based content for live and on-demand delivery. Windows Media Encoder enables new capabilities for the type and quality of audio and video content you can create for the Web.

Producing audio and video for the Web is as much art as it is science. While this document is not meant to clear up all of the mysteries of content creation, it does provide a very targeted, step-by-step introduction to this version of Windows Media Encoder and will get you started on some of the new capabilities available in Microsoft® Windows Media™ Technologies.

This document covers the following topics:

  • Capturing and Encoding Screen Content. Describes how to perform screen capture from within the encoder, and how to use the new Microsoft Windows Media Screen codec version 7.0 with screen capture files.

  • Using Video Optimization Filters. Details how to use the deinterlacing and inverse telecine video optimizations.

  • Encoding High-Motion Content at 60 FPS. Provides steps for creating 60-frame-per-second content at 320 x 240 resolution for sports and other high-motion content.

  • For More Information. Provides links to additional information about using Windows Media Encoder.

Capturing and Encoding Screen Content

The screen capture feature of Windows Media Encoder enables you to capture your entire desktop, individual windows, or a region of the screen and broadcast them or encode them to files just as you would any other content. In addition, the encoder enables you to use the Windows Media Screen codec version 7.0 to convert existing files for efficient Web delivery.

You can use the encoder to:

  • Source from .avi files that were created with a third-party screen-capture utility.

  • Capture content directly from your desktop using the screen capture feature.

  • Capture content from a card that is connected to a scan converter device.

Note: Artifacts can be introduced when an analog signal is run through a scan converter and converted to the National Television Standards Committee (NTSC) standard. These artifacts are amplified during encoding and can degrade the quality of the encoded video.

The encoder enables you to capture directly to a Windows Media file or to broadcast your session live. The session can be broadcast and archived simultaneously.

Because of the amount of data being manipulated and the CPU power necessary to compress it quickly, capturing screen images is a performance-intensive process. Therefore, the power of your computer, the size of the screen being captured, the color depth of the display (256 colors, 16-bit, and so on), and the specified frame rate all have an effect on performance. Also, the quality of your encoded screen images can be affected by the amount of motion that occurs during the encoding process. The Windows Media Screen codec is designed specifically for capturing large areas that involve little movement. Using this codec to capture a motion video, for example, will not give good results.

To ensure that the screen you capture will encode and play well:

  • Set your monitor to use a smaller display size. For example, capturing 1024 x 768 yields more data than capturing 640 x 480.

  • Set your monitor to use 256 colors or 16-bit color.

  • Use a profile that includes the Windows Media Screen codec. Three screen capture profiles are provided.

  • Specify a low frame rate in the profile.

  • Avoid multiple scene changes, such as opening and closing windows in rapid succession, during the capture.

If you are capturing to a file, the main encoder window is minimized while the screen is being captured so you can monitor the encoding statistics and the input and output images. Restoring the window to its regular size stops the encoding session. If you do not want the encoder window to minimize while a screen is being captured, on the Tools menu, click Options, click the General tab, and then clear Minimize main window to capture screen.

Note: If you are capturing a screen for broadcast and have selected a broadcast port, the encoder window does not minimize while the screen is being captured. Broadcasting a screen capture session overrides the Minimize during screen capture session, then stop on restore setting on the General tab.

Windows Media Encoder includes three system profiles that make use of the Windows Media Screen codec. Use them when capturing a screen directly from the encoder or when sourcing from files (such as .avi) that contain screen capture content. The three screen capture profiles are:

  1. Screen capture (live) for dial-up modems (28.8 Kbps). This profile is designed for encoding on a wide range of computer systems and is tuned for real-time or live capture. A lower frame rate setting is used to improve performance during capture, which can be an issue on less capable computers. The target audience has a dial-up modem connection (28.8 Kbps) and the output video resolution will match the resolution of the source (for example, the entire screen, selected window, and so on).

  2. Screen capture for dial-up modems (28.8 Kbps). This profile has a setting of five frames per second (fps). It creates a smoother video capture but requires higher CPU usage. The target audience has a dial-up modem connection (28.8 Kbps) and the output video resolution will match the resolution of the source file or capture device.

  3. Screen capture for e-mail and dual Integrated Services Digital Network (ISDN) (128 Kbps). This profile has a setting of ten fps. The target audience has a connection of 100 Kbps or more. Use this profile with content intended for distribution by e-mail or local playback. The output video resolution will match the resolution of the source file or capture device.

To Capture and Encode a Screen Using New Session Wizard

  1. Set up a session using New Session Wizard.

  2. Using the wizard, determine whether you want to perform a live broadcast or capture to a file.

  3. When prompted to configure devices, select Screen Capture for the video device.

  4. Click Configure to choose the capture area and quality.

  5. In Capture Source, select the item that you want to capture. You can select a specific window, the whole screen, or a region of the screen.

    If you select Window or Region of Screen, use the Region button to capture the exact area. The capture dimensions are set automatically when you point to the desired capture area. You can also set the dimensions manually.

    Note: When capturing a window, if you enlarge the window so that it exceeds the output size specified in your profile, part of the window will not be captured. If you decrease the size of the window so that it is smaller than the specified output size, the excess area around the window will be black.

  6. Click OK.

  7. When prompted to choose a profile, choose one of the three profiles that make use of the Windows Media Screen codec. Using a profile that doesn't use the Windows Media Screen codec may result in poor-quality encoding.

  8. Depending on the task you chose in step 2, specify either a broadcast port (or just use the default) or a capture file.

    Note: The encoder will allow you to connect up to 50 clients directly to the encoder for a broadcast or you can create a stream on the server running Microsoft Windows Media Services to source from this encoder.

  9. Provide the rest of the information required to complete the wizard, be sure the window or portion of the screen that you want to capture is on top, and then click Start.

To Encode an .AVI File Containing Screen Content Using New Session Wizard

  1. Set up a session using New Session Wizard.

  2. Using the wizard, click Convert an audio or video file into a Windows Media file.

  3. Specify the source and destination files.

  4. Click OK.

  5. When prompted to choose a profile, choose one that makes use of the Windows Media Screen codec.

  6. Provide the rest of the information required to complete the wizard, and then click Start to begin encoding.

    Note: When capturing to .avi using a third-party screen capture tool, use run-length encoding (RLE) compression or RGB uncompressed formats for files you plan to later convert using the encoder.

Using Video Optimization Filters

What most of us know as "video" is defined by the National Television Standards Committee (NTSC), which requires that analog data be interlaced and broadcast at 30 fps (or 25 fps for Phase Alternate Line (PAL) video). Interlaced video displays an image using a half-resolution video image known as a field, and uses two video fields to make a single frame of video. Each field of video is made up of every other line. Field one displays all the odd numbered lines, then field two goes back and displays all the even numbered lines. Interlacing saves bandwidth when the video is transmitted over the air or on cable, but the video quality suffers when interlaced content is transferred to a digital format. This affect comes into consideration for many different content sources, such as DV cameras, VHS tapes, 8mm, and TV sources such as cable. The Windows Media Encoder can de-interlace the content, filtering the alternate fields into a single frame to achieve a smoother result.

Film is normally shot at 24 fps. When transferred to another medium, such as DVD and videotape, extra fields are added to the content to achieve the standard 30 fps required by NTSC using a sequence called 3:2 pulldown. The extra frames are added in a telecine room, where the film to video transfer takes place. Windows Media Encoder can remove the added fields of video and encode the image at 24 fps, resulting in a smaller file size and higher quality image. The process of removing the extra frames is called inverse telecine. PAL video does not need these extra fields of video as the frame rate is close enough that the film is just transferred at 25 fps.

To Deinterlace Video

  1. After creating a new session, on the Session menu, click Properties.

  2. Click the Sources tab. Click the source containing the video that you want to deinterlace, and then click Change.

  3. Click the Video Optimization tab.

  4. Click Deinterlace.

  5. If using multiple source groups, repeat steps 2 through 4 for each.

    Note: Use the deinterlace feature only with a video source that was previously interlaced.

To Convert Film-Based Content From 30 FPS to 24 FPS (Inverse Telecine)

  1. On the Session menu, click Properties.

  2. Click the Sources tab, select the source containing the video that you want to convert to 24 fps, and then click Change.

  3. Click the Video Optimization tab.

  4. Click Inverse telecine.

  5. If using multiple source groups, repeat steps 2 through 4 for each.

    Note: Use the inverse telecine feature only with a video source that was previously telecined with a frame rate of 30 fps. Make sure that Inverse telecine is not selected when capturing screens.

Encoding High-Motion Content at 60 FPS

Windows Media Encoder contains several high-motion profiles that enable you to encode high-motion content, such as a sporting event at 60 fps and 320 x 240 resolution. High-motion content is content that contains a lot of movement but few scene changes.

To produce content at 60 fps, begin with a source that is interlaced at full-height resolution. Full height for NTSC is 480 pixels. The resolution must be full height so the encoder can capture all the interleaved fields.

During the encoding process, you deinterlace the content to produce two half-height 30 fps frames that are joined together into a single frame and played at 60 fps.

To Encode High-Motion Content

  1. Create a session using New Session Wizard.

  2. Using the wizard, click either Capture audio or video from attached devices or computer screen or Convert an audio or video file into a Windows Media file.

    Note: The encoder will automatically capture at full resolution when capturing in real time from a device. When sourcing from .avi files, the file must have full height (480 pixels) resolution.

  3. When asked to choose a profile, choose one that is designed for high motion. The system high-motion profiles say High motion in the title.

  4. Provide the required information to complete the wizard.

  5. On the Session menu, click Properties.

  6. Click the Sources tab, select the source that you want to encode at 60 fps, and then click Change.

  7. Click the Video Optimization tab, click Deinterlace, and then click OK.

  8. Click OK again to close the Session Properties dialog box.

  9. Click Start to begin encoding.

For More Information

To learn more about Windows Media Encoder, see Windows Media Encoder Help. To learn more about encoding configuration and hardware requirements, and to download the Encoder 7, see the Windows Media Encoder page on the Windows Media product site ( http://www.microsoft.com/windows/windowsmedia/forpros/encoder/default.mspx ).

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