Kmixer Plays Only the Top 16 Bits of 24-Bit or 32-Bit Audio (308883)


The information in this article applies to:

  • Microsoft Windows 2000 Server SP1
  • Microsoft Windows 2000 Server SP2
  • Microsoft Windows 2000 Advanced Server SP1
  • Microsoft Windows 2000 Advanced Server SP2
  • Microsoft Windows 2000 Professional SP1
  • Microsoft Windows 2000 Professional SP2
This article was previously published under Q308883

SYMPTOMS

The following symptoms may occur:
  • You cannot play high-quality audio in Kmixer: Kmixer truncates all 24-bit and 32-bit data to 16 bits internally. This means that you cannot play source material with 24-bit or 32-bit samples by using the Wave or DSOUND APIs and have 24-bit or 32-bit samples arrive at the hardware intact (except for certain kinds of hardware). The bottom 8 or 16 bits are discarded. This occurs on both capture and playback.
  • Problems in audio capture: If the driver completes captured buffers out of order, Kmixer does not correctly reorder them when it sends the data to its clients. Kmixer incorrectly sends the more recent audio samples first, and then older data second, instead of always sending oldest-to-newest samples. This means that problems can occur in capture if you are using the DSOUND and Wave APIs to capture audio.
  • Silence on audio capture: If Kmixer is configured to use a floating point for its internal calculations (this in general is rare), you receive silence on capture.

CAUSE

These problems occur because the kernel does not deal well with high sample rates and concurrency.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack

The English version of this fix should have the following file attributes or later: 
   Date         Time     Version      Size     File name
   ------------------------------------------------------
   22-Mar-2002  19:15  5.0.2195.5237  149,840  Kmixer.sys

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article. This problem was first corrected in Windows 2000 Service Pack 3.

MORE INFORMATION

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

265173 The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:

296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot

For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:

249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes

Modification Type:MinorLast Reviewed:9/26/2005
Keywords:kbHotfixServer kbQFE kbbug kbfix kbOSWin2000fix kbWin2000PreSP3Fix kbWin2000sp3fix KB308883
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