8.5 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 with Windows 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
hardware. The true and effective latency is configured within the MME application!
Attention: the DMA buffers must not be larger than the application's buffers. 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.
Playback will be stuttering and audio will be distorted.
Example: when you set the Hammerfall to 512 you can't use 128 in any program. But setting
DMA 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 (especially
VIA based) suffer from crackling at settings below 512. Be sure to set the buffer size to 512 or
higher in such a case (or trash the motherboard...).
8.6 Multi-Client Operation
RME audio cards 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!
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 (default in Cubase, Master bus), this playback pair
can't be used in Gigasampler/Studio (GSIF) nor under MME (WaveLab etc) anymore (the
inputs can be used at the same time). This is no limitation at all, because TotalMix allows any
output routing, and with this a playback of multiple software on the same hardware outputs.
RME audio cards 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. The inputs can be used simultaneously.
An exception is our sophisticated tool DIGICheck. It operates like an ASIO host, using a special
technique to access playback channels already occupied. Therefore DIGICheck is able to
perform an analyzis and display of playback data from any software, no matter which format
the software uses.
User's Guide Hammerfall DSP 9632 © RME