RME Audio Hammerfall HDSPe MADIface, User Manual

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User's Guide HDSPe MADIface
© RME
12.3 Notes on WDM
The driver offers a WDM streaming device per stereo pair, like
HDSP MADI (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 12.5),
Sonar not only finds the stereo device mentioned above, but also the 8-channel interleaved
devices, and adds the channel number at the end:
HDSP MADI (1+2) is the first stereo device
HDSP MADI (3+4) is the next stereo device
HDSP MADI (1+2) 3/4 are the channels 3/4 of the first 8-channel interleaved device.
We recommend to not use these special interleaved devices. Also note that it is not possible to
use one stereo channel twice (the basic and the interleaved device), even with different applica-
tions.
Information on multichannel WDM is found in chapter 12.5.
12.4 Channel Count under WDM
The MADIface allows the use of sample rates up to 192 kHz via the MADI interface. For this to
work single-channel data is spread to two or four channels using the
Sample Multiplexing tech-
nique. Therefore the number of channels is reduced to 32 or 16 respectively.
It is nearly impossible to change the number of WDM devices without a reboot of the computer.
So when the MADIface changes to Double Speed (88.2/96 kHz) or Quad Speed mode
(176.4/192 kHz) all devices stay present, but are partly inactive.
WDM Stereo devices Double Speed Quad Speed
MADI (1+2 to 15+16) MADI (1+2 to 15+16) MADI (1+2 to 15+16)
MADI (17+18 to 31+32) MADI (17+18 to 31+32) MADI (17+18 to 31+32)
MADI (33+34 to 63+64) MADI (33+34 to 63+64) MADI (33+34 to 63+64)