B4 II – 21
computers are generally not set up for low latency; attempting to play in real
time through B4 II will probably be unsatisfying because of the delay.
Any computer-based audio system has some delay between the audio input
and output. As a result, if you’re playing a MIDI keyboard through B4 II, you
may hear an annoying delay between the time you hit a key and hear a sound.
Even the most powerful computer can only do a certain number of calculations
per second; generating and processing sounds demands a lot from a computer,
so it’s important to minimize any computer-based delays.
Fortunately, three main factors make delays virtually insignicant, assuming
you have a suitable computer setup (see System Requirements).
• Today’s multi-GigaHertz computers are so fast they dramatically reduce
latency.
• Many sound cards and audio interfaces include drivers optimized for
low latency.
• NI’s software has been optimized to function as efficiently as
possible.
Use Low-Latency Drivers
Drivers are pieces of code that handle communications between your computer
and audio interface, whether built into a computer or attached via USB or
FireWire. The more efciently they transfer data between audio interface and
computer, the lower the latency.
B4 II works with two low-latency driver types:
• ASIO (Advanced Streaming Input Output). This cross-platform protocol
was originally developed by Steinberg.
• Core Audio (Mac only). This low-latency protocol was created by Apple
for the Macintosh, starting with OS X.
If your audio interface does not support one of these protocols, you will likely
hear an audible delay if you play through B4 II in real time. Although B4 II can
work with the DirectSound and MME drivers common in Windows machines,
you will probably not have a satisfying playing experience.
How Low Can You Go?
1.5 ms of latency approaches the theoretical minimum, because it will always
take some time to convert a keyboard press into MIDI data, than convert B4's
digital audio out to analog. However, note that ultra-low latency settings (or
higher sampling rates) make your computer work harder, which may limit the
