User Manual

User's Guide Fireface UCX © RME

9.3 Notes on WDM

The driver offers a WDM streaming device per stereo pair, like Analog 3+4 (Fireface UCX).

WDM streaming is Microsoft's current driver and audio system, directly embedded into the op-

erating system. WDM streaming is hardly usable for professional music purposes, as all data is

processed by the so called Kernel Mixer, causing a latency of at least 30 ms. Additionally, WDM

can perform sample rate conversions unnoticed, cause offsets between record and playback

data, block channels unintentionally and much more.

Several programs do not offer any direct device selection. Instead they use the playback device

selected in Windows under

XP: <Control Panel/ Sounds and Multimedia/ Audio>

Vista/7: <Control Panel/ Sound/ Playback>

The program Sonar from Cakewalk is unique in many ways. Sonar uses the so called WDM

Kernel Streaming, bypassing the WDM mixer, thus achieves a similar performance to ASIO.

Because of the driver's multichannel streaming ability Sonar not only finds the stereo device

mentioned above, but also the 8-channel interleaved devices, and adds the channel number at

the end:

Fireface Analog (1+2) 1/2 is the first stereo device

Fireface Analog (3+4) is the next stereo device

Fireface Analog (1+2) 3/4 are the channels 3/4 of the first 8-channel interleaved device.

It is not recommended to use these special interleaved devices. Also it is not possible to use

one stereo channel twice (the basic and the interleaved device).

Multi-Channel using WDM

The WDM Streaming device Loudspeaker (Analog 1+2) of the RME driver can operate as usual

stereo device, or as up to 8-channel device.

An 8-channel playback using the Windows Media Player requires the speaker setup 7.1 Sur-

round. Configure as follows:

XP: >Control Panel /Sounds and Multimedia /Audio /Volume /Speaker Settings /Advanced <

Vista/7: >Control Panel /Sound /Playback /Loudspeaker /Configure <