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 |
| sample value of 16,384 can be referred to having a value of |
|
|
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 | A system for delivering songs, videos, and other media over the Internet in a file format |
Management (DRM) | that protects copyrighted material. Current proposals include some form of certificates |
| that validate copyright ownership and restrict unauthorized redistribution. |
|
|
Digital Signal Processing | A general term describing anything that alters digital data. Signal processors have existed |
(DSP) | for a very long time (tone controls, distortion boxes, |
| (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® |
| uses the DirectX Media Streaming Services (DMSS) API. Because DMSS is a standard API, a |
| DirectX |
|
|
Downbeat | This term is used in the Beatmapper to refer to the first beat of the first measure. |
|
|
Downloadable Sound | A DLS file stores a custom sound set that you can load into your soft synth, giving you |
(DLS) | 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 |
| 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 |
|
|
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. |
APPENDIX E 313