When you play back certain pieces of MPEG4 content, the rendered video may appear blocky.

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This behavior occurs because the MPEG4 decoder does not correctly put a boundary on all quantized coefficients. Therefore, the decoder uses the wrong prediction direction, and the video looks blocky.

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A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next release that contains this hotfix.

The following file is available for download from the Microsoft Download Center:
Download the WindowsMedia9-KB872899-x86-ENU.exe package now. (http://download.microsoft.com/download/8/7/6/876d69b6-f66d-4712-b81c-f241a1438382/windowsmedia9-kb872899-x86-enu.exe)

For additional 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 to prevent any unauthorized changes to the file.

The English version of this hotfix has the file attributes (or later) 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.

   Date         Time   Version            Size    File name
   --------------------------------------------------------------
   14-Jul-2004  05:46  9.0.0.3220        385,024  Mp4sdmod.dll     

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

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