Appendix E: PureWave and SuperChannel
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Appendix E: PureWave and SuperChannel
PureWave versus WDM
With the WDM driver, you can run each wave device in either WDM mode or
PureWave mode. Here’s a chart explaining the differences between the two.
WDM wave
PureWave
Audio data may be resampled,
dithered, or otherwise modified
Audio data is sent to the hardware
unchanged
Not all 24 bit applications are
supported
All 24 bit applications are supported
30 milliseconds of latency added for
both playback and record
Latency may be adjusted to best suit
your machine.
Note that this only applies to software that uses the wave/MME API to
communicate with audio hardware. Applications that use other APIs, such as
ASIO or GSIF, do not benefit from PureWave as they already enjoy a direct
connection to the hardware.
Despite all this, you may still wish to use WDM mode. There are applications,
most notably Cakewalk’s SONAR, that take advantage of WDM Kernel
Streaming. WDM Kernel Streaming allows the application to bypass the kernel
mixer; in that case, you should definitely use WDM mode.
Surround sound playback applications such as WinDVD or PowerDVD should use
the WDM mode; see below for details.
Please note that under PureWave mode, DirectSound is not supported.
PureWave only works in Windows 2000 and Windows XP.
