Intel Fireface 800 - Manual (Page 26)

26 User's Guide Fireface 800 © RME
12.3 Notes on WDM
The driver offers a WDM streaming device per stereo pair, like Fireface ADAT 1 (1+2). WDM
streaming is Microsoft's current driver and audio system, directly embedded into the operating
system. WDM streaming is hardly usable for professional music purposes, as all data is proc-
essed 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 (option Interleaved, see chapter 12.4),
Sonar not only finds the stereo device mentioned above, but also the 8-channel interleaved
devices, and adds the channel number at the end:
RayDAT ADAT (1+2) is the first stereo device
RayDAT ADAT (3+4) is the next stereo device
RayDAT ADAT (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 <
12.4 Channel Count under WDM
The HDSP system’s ADAT optical interfaces allow to record sample rates of up to 96 kHz using
a standard ADAT recorder. For this to work single-channel data is spread to two ADAT chan-
nels using the Sample Multiplexing technique. This reduces the number of available ADAT
channels from 8 to 4 per ADAT port.
Whenever the Fireface changes into Double Speed (88.2/96 kHz) or Quad Speed mode
(176.4/192 kHz) all devices no longer available vanish automatically.