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 ACID, 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 Windows to connect different hardware and software. For
example, a sound card device driver is used by Windows software to control sound card
recording and playback.
Digital Rights
Management (DRM)
A system for delivering songs, videos, and other media over the Internet in a file format
that protects copyrighted material. Current proposals include some form of certificates
that validate copyright ownership and restrict unauthorized redistribution.
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.
DirectX A set of Application Program Interfaces designed by Microsoft for multimedia
development. A DirectX® plug-in, such as the Sony Noise Reduction™ DirectX Plug-In,
uses the DirectX Media Streaming Services (DMSS) API. Because DMSS is a standard API, a
DirectX plug-in can be used in any application that supports DMSS.
Downbeat This term is used in the Beatmapper to refer to the first beat of the first measure.
Downloadable Sound
(DLS)
A DLS file stores a custom sound set that you can load into your soft synth, giving you
another set of voices for MIDI playback.
Drag and Drop A quick way to perform certain operations using the mouse. To drag and drop, you click
and hold an item, 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.
Envelopes Envelopes allow you to automate the change of a certain parameter over time. In the case
of volume, you can create a fade out (which requires a change over time) by adding an
envelope and creating a point in the line to indicate where the fade starts. Then you pull
the end point of the envelope down to -inf.
Equalization (EQ) Equalizing a sound file is a process by which certain frequency bands are raised or
lowered in level. EQ has various uses. The most common use for ACID users is to simply
adjust the subjective timbral qualities of a sound.
Event An instance of a media file on a track. An event may play an entire media file or a portion
of the file.
File Format A file format specifies the way in which data is stored. In Windows, the most common
audio file format is the Microsoft WAV format.
Frame Rate Audio uses frame rates only for the purposes of synching to video or other audio. To
synchronize with audio, a rate of 30 fps (frames per second) is typically used. To
synchronize with video, 29.97 fps drop is usually used.
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