ID Number: Q63347
1.00
WINDOWS
Summary:
In the Microsoft Multimedia Windows environment, 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.
This problem generally occurs only when running under enhanced mode
Multimedia 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.
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.
Additional reference words: 1.00 3.00