System information
Decibel (dB)
A unit used to represent a ratio between two numbers using a logarithmic scale. For example, when
comparing the numbers 14 and 7, you could say 14 is two times greater than the number 7; or you could
say 14 is 6 dB greater than the number 7. Where did we pull that 6 dB from? Engineers use the equation dB
= 20 x log (V1/V2) when comparing two instantaneous values. Decibels are commonly used when dealing
with sound because the ear perceives loudness in a logarithmic scale.
In Vegas Pro, most measurements are given in decibels. For example, if you want to double the amplitude
of a sound, you apply a 6 dB gain. A sample value of 32,767 (maximum positive sample value for 16-bit
sound) can be referred to as having a value of 0 dB. Likewise, a sample value of 16,384 can be referred to
having a value of -6 dB.
Device Driver
A program that enables the Windows operating system to connect different hardware and software. For
example, a sound card device driver is used by software to control sound card recording and playback.
Digital Signal Processing (DSP)
A general term describing anything that alters digital data. Signal processors have existed for a very long
time (tone controls, distortion boxes, wah-wah pedals) in the analog (electrical) domain. Digital Signal
Processors alter the data after it has been digitized by using a combination of programming and
mathematical techniques. DSP techniques are used to perform many effects such as equalization and
reverb simulation.
Since most DSP is performed with simple arithmetic operations (additions and multiplications), both your
computer's processor and specialized DSP chips can be used to perform any DSP operation. The difference
is that DSP chips are optimized specifically for mathematical functions while your computer's
microprocessor is not. This results in a difference in processing speed.
Dithering
The practice of adding noise to a signal to mask quantization noise.
Drag and Drop
A quick way to perform certain operations using the mouse in Vegas Pro. To drag and drop, you click and
hold a highlighted selection, drag it (hold the left-mouse button down and move the mouse) and drop it (let
go of the mouse button) at another position on the screen.
Dynamic Range
The difference between the maximum and minimum signal levels. It can refer to a musical performance
(high volume vs. low volume signals) or to electrical equipment (peak level before distortion vs. noise floor).
For example, orchestral music has a wide dynamic range while thrash metal has a very small (always loud)
range.
GLOSSARY637