FIX: Windows Media Encoder 9 Series may get ahead of the network output while looping file sources (872900)

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256986 Description of the Microsoft Windows Registry

SYMPTOMS

You configure the Microsoft Windows Media Encoder 9 Series to loop a file as a broadcast source. As multiple iterations occur, the encoder may be getting slightly ahead of the network output. When this problem is occurring, the encoder may take progressively longer to stop, depending on how long it has been running. Additionally, in Task Manager, you may notice that the encoder process is using more and more memory.

This problem occurs only if you are switching between multiple file sources.

CAUSE

The encoder is adding small bits of silence to the stream to compensate for the time that it takes to switch between live sources. In this case, the encoder is configured to use file sources that may not have to have this additional audio gap. Additionally, the encoder starts processing the next source group before the previous source group has finished encoding. Together, these issues cause the encoder to slowly get ahead of itself.

THINGS TO TRY

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Before you apply the hotfix that is mentioned in the "Resolution" section, it is a good idea to try the following steps.

Note See the "More Information" section for information about the locations and the values of the registry keys that are mentioned in these steps.

Set the Silence Audio Gap registry value to 0 (0x0), and then monitor the encoder to see if the problem stops.

Note The Silence Audio Gap registry value exists in the release version of the Windows Media Encoder 9 Series. You do not have to apply the hotfix to modify this value. This hotfix is only required if step 1 does not resolve the problem.
If step 1 does not resolve the problem, apply the hotfix, and then set the Silence Audio Gap registry value to its default value of 500 (0x1F4) milliseconds.
If the problem is still occurring, but to a lesser degree, after you perform step 2, set the Silence Audio Gap registry value back to 0 (0x0), and then monitor the encoder to see if the problem stops.
If step 3 does not resolve the problem, increase the MAX Slow Down Sleep registry value. For example, set the value to 3000 (0xBB8) or 4000 (0xFA0) milliseconds. Leave the Silence Audio Gap registry value at 0 (0x0).

RESOLUTION

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

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

Download the WindowsMedia9-KB872900-x86-ENU.exe package now.

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

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
   -------------------------------------------------------
   13-Jul-2004  08:06  9.0.0.3219  1,574,400  Wmenceng.dll

MORE INFORMATION

The following registry keys are associated with this article:

To reduce the amount of silence that the encoder is automatically adding between source group switches, add the following REG_DWORD registry key:
HKCR\Software\Microsoft\Windows Media Tools\Encoder\Silence Audio Gap
- The default value for this key is 500 milliseconds (0x1F4).
- Typically, if you are noticing problems, you can improve performance by setting this value closer to 0 (0x0) or equal to 0 (0x0).
By default, this hotfix enables a self-regulating mechanism to help make sure that the source group changes are not occurring too quickly. The following REG_DWORD registry key will help limit the time that the encoder will wait during a source group switch:
HKCR\Software\Microsoft\Windows Media Tools\Encoder\MAX Slow Down Sleep
- The default value for this key is 2000 milliseconds (0x2000).
- The more you increase this value, the longer the encoder may wait during a source group switch.
- To disable the self-regulating mechanism, set the value of this key to 0 (0x0).

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates