Microsoft KB Archive/817865

= Windows 2000 USB audio capture may drop isochronous packets =

Article ID: 817865

Article Last Modified on 10/12/2005

-

APPLIES TO


 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Service Pack 4
 * Microsoft Windows 2000 Service Pack 3
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 1
 * Microsoft Windows 2000 Service Pack 3
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Service Pack 2
 * Microsoft Windows 2000 Service Pack 1

-



SYMPTOMS
When you capture audio by using a universal serial bus (USB) audio device on Windows 2000, the USB audio driver may occasionally drop audio packets. This may result in gaps or clicks in the captured audio.



CAUSE
The Windows 2000 USB audio driver (Usbaudio.sys) submits two buffers at a time to the USB driver stack when you capture audio. Each buffer holds 10 milliseconds of audio. Sometimes, the USB audio driver cannot process and resubmit one of these buffers to the USB driver stack before the other buffer becomes full. This results in lost isochronous audio packets because the capture buffers are not available.



RESOLUTION
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 2000 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.

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.   Date         Time   Version         Size    File name 08-Apr-2003 19:04  5.0.2195.6702   68,944  Usbaudio.sys



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



MORE INFORMATION
For more information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the following article number to view the article in the Microsoft Knowledge Base:

265173 The Datacenter program and Windows 2000 Datacenter Server product

Keywords: kbbug kbfix kbwin2000presp4fix kbqfe kbusb kbhotfixserver KB817865

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.