Low Latency Under Mme; Multi-Client Operation - RME Audio Multiface User Manual

12.3 Low Latency under MME (Buffer Size Adjustment)
Using Windows 95 or 98 the MME buffer size was nothing to worry about. Latencies below 46
ms were not possible. Meanwhile both computers and operating system have become much
more powerful, and since Windows ME/2000/XP latencies far lower can be used. SAWStudio
and Sonar allowed to use such low settings from the start. Sequoia was updated in version
5.91, WaveLab in version 3.04.
In the HDSP's Settings dialog the MME buffersize (in fact the DMA buffer size) is set with the
same buttons as the ASIO buffer size. Our test computers allow to use settings down to 64
samples without clicks. Please note that this setting only defines the buffer size of the hard-
ware. The true and effective latency is configured within the MME application!
Attention: the DMA buffers must not be larger than the application's buffers. Playback will be
stuttering and audio will be distorted.
This case can happen unnoticed when using ASIO and MME at the same time (multi-client)
and setting ASIO to 186 ms, while the buffers in the MME application are still set for a lower
latency.
Example: when you set the Hammerfall to 512 you can't use 128 in any program. But setting
the buffer size to 128 allows to use 128 and all higher values within the software.
Please also note that this is a you're-welcome-to-try feature. We can't guarantee that you will
be able to use 3 or 6 ms with MME. Simply check out by yourself which lowest setting your
system and software allows. Some motherboards with insufficient PCI bandwidth (like older VIA
boards) suffer from crackling at settings below 512. Be sure to set the buffer size to 512 or
higher in such a case (or get a new motherboard).

12.4 Multi-client Operation

RME audio interfaces support multi-client operation. This means several programs can be used
at the same time. Also all formats, like ASIO, MME and GSIF can be used simultaneously. The
use of multi-client operation requires to follow two simple rules:
Multi-client operation requires identical sample rates!
I.e. it is not possible to use one software with 44.1 kHz and the other with 48 kHz.
Different software can not use the same channels at the same time.
If for example Cubase uses channels 1/2, this playback pair can't be used in Gigasam-
pler/Studio (GSIF) nor under MME (WaveLab etc.) anymore. This is no limitation at all, be-
cause TotalMix allows any output routing, and with this a playback of multiple software on the
same hardware outputs. Note that the inputs can be used at the same time, as the driver sends
the data to all applications simultaneously.
ASIO-Multiclient
RME audio interfaces support ASIO multi-client operation. It is possible to use more than one
ASIO software at the same time. Again the sample rate has to be identical, and each software
has to use its own playback channels. Once again the same inputs can be used simultaneously.
RME's sophisticated tool DIGICheck is an exception to this rule. It operates like an ASIO host,
using a special technique to access playback channels already occupied. Therefore DIGICheck
is able to analyse and display playback data from any software, no matter which format the
software uses.
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User's Guide HDSP System Multiface © RME