Any Soft Virtual Sound Device Software Buffers Altogether

In both cases its generally possible to connect them up such that you can hear the performance with effects, but still record it dry, for maximum flexibility during later mixdowns.

Here you can see the Control Panels for the Echo (left) and Emu (right) ranges, as launched from the Cubase SX Device Setup window.

Sometimes this delay may be as much as a second, making real time performances almost impossible.

Newcomers to computer music soon cotton on to the fact that this is because of latency and buffer sizes, but are often left wondering just what to adjust and what the best setting is.

The ideal setting can depend on quite a few different factors, including your particular PC and how you work with audio, while the parameters youre able to change, and how best to do it, can also vary considerably depending on which MIDI Audio application you use.

To maintain a continuous audio stream, small amounts of system RAM (buffers) are used to temporarily store a chunk of audio at a time.

Similarly, during audio recording the incoming data slowly fills up a second set of buffers, and Windows comes back every so often to grab a chunk of this and save it to your hard drive.

If the buffers are far too small, these glitches occur more often, firstly giving rise to occasional crackles and eventually to almost continuous interruptions that sound like distortion as the audio starts to break up regularly.

This is latency, and is most obvious in two situations: when playing a soft synth or soft sampler in real time, or when recording a performance.

In the first case you may be pressing notes on your MIDI keyboard in real time, but the generated waveforms wont be heard until the next buffer is passed to the soundcard.

You may not even be aware of a slight time lag at all (see Acceptable Latency Values box), but as it gets longer it will eventually become noticeable, then annoying, and finally unmanageable.

Some plug-ins add latency to the audio path, as revealed by this Plug-In Information window in Cubase SX.

The window shows which plug-ins exhibit additional latency when used, and whether or not to automatically compensate for it.

Any tracks in your song using these effects would be delayed compared with the rest, so to bring them all back into perfect sync most MIDI Audio applications now offer automatic delay compensation throughout the entire audio path.

Activating this function during an audio recording or soft-synth performance may allow less real-time latency.

Fortunately, many audio interfaces provide so-called zero-latency monitoring for recording purposes.

Any Soft Virtual Sound Device Software Buffers Altogether

This bypasses the software buffers altogether, routing the interface input directly to one of its outputs.

However, as I explained in my article The Truth About Latency (see Further Reading box), the total latency value isnt just that of the buffers.

The audio signals also have to pass through the A-D and D-A converters on their way into and out of the computer, which adds a small further delay.

So zero-latency monitoring actually means about 2ms latency, which is still almost undetectable in most situations.

Its incredibly useful during recording, because the performers can listen to their live performance without any audible delay, which makes it far easier to monitor via headphones, for instance.

However, it does have one unfortunate side-effect: you cant hear the input signal with plug-in effects, which prevents you from giving vocalists some reverb in the cans to help with pitching, or guitarists some distortion, for example.

One way around this is to buy an interface with on-board DSP effects and use them instead.