Microsoft KB Archive/818213

= FIX: Digital TV tuner card audio is muted after you Windows Messenger starts on Windows XP SP1 =

Article ID: 818213

Article Last Modified on 10/12/2005

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APPLIES TO


 * Microsoft Windows XP Home Edition
 * Microsoft Windows XP Professional

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SYMPTOMS
When you watch TV with a digital TV tuner card, and Microsoft Windows Messenger starts, the audio for the TV channel that you are watching is muted. This problem does not occur with versions of Microsoft Windows XP that are earlier than Windows XP Service Pack 1 (SP1).



CAUSE
This problem occurs because the Telephony API (TAPI) in Windows XP SP1 queries input devices by building a DirectShow capture graph. Windows Messenger calls the TAPI API. Because the TV tuner is already being used, no PIN instances are available. Therefore, the query is unsuccessful. The analog audio/video crossbar filter, or ksxbar, incorrectly mutes all audio input during the capture graph cleanup time. The analog audio/video crossbar filter is a DirectShow system component.



Service pack information
To resolve this problem, obtain the latest service pack for Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Hotfix information
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 Windows XP service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

File information
The English version of this 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 17-Apr-2003 02:34  5.1.2600.1207  38,400  Ksxbar.ax



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

This problem was first corrected in Windows XP Service Pack 2.

