Lynx Studio E44 - Manual (Page 42)

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8.2.1.3 Controlling Latency by Changing the Buffer Size
Latency in an audio interface can be defined as the time required to process a sample from an
application to the interface’s audio output. A number of factors determine the achievable
latency performance of a Lynx card: processor speed, operating system, sample rate, number
of utilized record or play channels, system efficiency, etc.
Latency can be manipulated by changing the size of the buffers used to transfer data to and
from the E22/E44. The higher the buffer size, the less work the computer has to do to stream
audio to the hardware. However, a higher buffer results in more latency. Also, the higher the
sample rate, the higher the buffer size needs to be. For instance, a buffer size of 128 samples
at a sample rate of 44.1kHz results in 2.9 milliseconds of latency. However, at 96kHz, a
buffer size of 128 = 1.33 milliseconds. Therefore the buffer size needs to be increased as the
sample rate increases to maintain the same level of performance. If the buffer size is too low,
you can experience clicks, pops or distortion in the audio. This is the result of buffer under-
runs, when the audio buffer is momentarily depleted because the computer cannot deliver
samples quickly enough to keep it filled.
Why is latency important? It isn’t in every case. Here are the main conditions where low
latency is important:
* Software input monitoring. This is where you are monitoring through your audio
software the input signals to be recorded. The software is re-directing the input signal back
out to a play device. If the buffer is too high here the performer will hear a noticeable delay
between the notes they are playing and hearing the sound back through the computer. Note
that with the E22/E44, zero latency hardware monitoring is available as an alternative to
software monitoring. See
Section 7: Lynx Mixer Application Reference .
* Virtual Instruments. Generally this would involve using a software synthesizer or other
virtual sound source as an alternative to dedicated hardware like a keyboard or tone module.
Frequently one would play these instruments with some sort of MIDI controller. The delay
between a key being struck and hearing the resulting note from the virtual instrument is a
function of latency.
* Mix Automation. Virtually all DAW applications feature some sort of Mix Automation,
and most allow an external Mix surface or MIDI controller to facilitate mixing within the
software environment. Whether using onscreen faders or a MIDI surface of some sort,
latency will determine the delay between manipulating a fader or knob, and that move being
reflected in the project.