FIX: Images in content appear less clear after you upgrade to Windows Media Video 9 Screen codec

After you upgrade to Microsoft Windows Media Encoder 9 Series, content that has been encoded by using the Windows Media Video 9 Screen codec may not look as good as content that has been encoded by using the Windows Media Video 7 Screen codec. For example, an area of an image or the edge of an image may not appear as clear as before you upgraded.

This problem occurs because the Windows Media Video 9 Screen codec sometimes uses a different compression algorithm than the Windows Media Video 7 Screen codec.

The following terms are used to describe the cause of this problem:

• Lossless encoding. There is no loss of data between the original file and the decompressed encoded file. During the encoding process, data is not discarded to achieve the smaller file size. Therefore, lossless encoding provides a lower compression ratio than lossy encoding.
• Lossy encoding. There is a loss of data to achieve smaller file sizes. Lossy encoding provides a higher compression ratio than lossless encoding.

The Windows Media Video 7 Screen codec uses a lossless compression algorithm. Some types of content can cause the codec to drop data because of the complexity of the source material. For example, the complexity of Microsoft PowerPoint slides or Microsoft Internet Explorer windows can cause this problem.

To encode as many frames as possible, the Windows Media Video 9 Screen codec automatically switches between the lossy compression mode and the lossless compression mode, depending on the complexity of the detected content. Overall, this choice of compression mode helps to improve the performance of the codec. If the content includes either text or defined lines, the lossy algorithm may blur them as part of the encoding process. Because of this change, some encoded frames do not appear as clear as when the frames are encoded with the lossless compression of the Windows Media Video 7 Screen codec.

The following file is available for download from the Microsoft Download Center:

Download the WindowsMedia9-KB837171-ENU.exe package now. (http://download.microsoft.com/download/4/f/5/4f5fabd2-fce8-4f9a-ae20-6808b1555a43/windowsmedia9-kb837171-enu.exe)
For more information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help prevent any unauthorized changes to the file.

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To enable the fix to permit the Windows Media Video 9 Screen codec to behave similar to the Windows Media Video 7 Screen codec, you must add the following REG_DWORD registry key:Note If you enable this key, the performance on the encoding computer may be affected.

The key can have one of the following DWORD values:

• 0x0 - The Windows Media Video 9 Screen codec uses its default behavior.
• 0x1 - The Windows Media Video 9 Screen codec will use the same behavior as the Windows Media Video 7 Screen codec.

When you install this hotfix, you (the content creator) benefit from the other features in the Windows Media Video 9 Screen codec together with the lossless quality of the Windows Media Video 7 Screen codec.