PRB: Clicking Noises While Playing Sounds on SoundBlaster Card (63347)
The information in this article applies to:
- Microsoft Windows Software Development Kit (SDK) 3.0
- Microsoft Windows Software Development Kit (SDK) 3.1
This article was previously published under Q63347 SYMPTOMS
While playing some sounds on earlier models of the SoundBlaster card, some
periodic popping or clicking sounds may occur. These cards are generally
referred to as the 1.0 DSP (digital sound processing) design. Cards
using the version 2.0 DSP design can use version 1.5 of the SoundBlaster
Multimedia Device Driver (SNDBLST2.DRV), which eliminates this situation.
CAUSE
This problem generally occurs only when running under enhanced mode
Windows. It is a result of the current design of the SoundBlaster hardware,
in conjunction with the interrupt latency inherent in enhanced mode
Windows.
The SoundBlaster uses DMA (direct memory access) to transfer small
pieces of the sound data from main memory to the card, and generates a
hardware interrupt only when its buffer becomes empty. Upon receipt of
this interrupt, the SoundBlaster driver prepares the next piece of
sound data and initiates another DMA transfer. This process continues
until the sound has been completely played out.
When running in Windows enhanced mode, the interrupt latency is often
more than a few sample periods, which results in the noises discussed
earlier.
RESOLUTION
Creative Labs has corrected the problem with version 2.0 DSP along
with version 1.5 of the Sound Blaster Multimedia Device Driver. In
addition, the new card from Creative Labs, the Sound Blaster Pro, does
not exhibit the clicking problem. Contact Creative Labs to update
earlier Sound Blaster cards to version 2.0 DSP.
For testing purposes, this problem can be resolved by running in
Windows standard mode, where interrupt latencies are lower.
| Modification Type: | Major | Last Reviewed: | 10/30/2003 |
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| Keywords: | kb16bitonly KB63347 |
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