User Manual

400 Glossary
and so protects both the audio data and its associated metadata.
The DDP image is a data file, and when burned to optical media, is a data disc. As such,
it has the full measure of CIRC error-correction to allow error-free copying of files on your
computer and across networks (including the internet). It’s also why you often need a DVD-R
to contain a DDP image of a CD, because the data redundancy is more robust in data form
than in streaming audio form.
Sending DDP files is "best practice" for disk replicators, who will upload the image file to
their network and burn a glass master directly from the image using specialist hardware/soft-
ware. CIRC error-correction will assure that the data matches the original, or it will stop the
process.
WaveLab can read DDP files by choosing File > Import > Audio DDP Image.... Glossary
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15.25 Decibel (dB)
Decibel (dB) is a logarithmic unit of measurement that expresses the size of a physical
quantity (usually sound pressure level, power or intensity) relative to a reference level.
Decibels are often used in matters of sound because the ear perceives loudness on a log-
arithmic scale. The equation dB = 20 x log(V1/V2) is often used by sound engineers com-
paring two values. Applying a gain of 3dB doubles the amplitude of a sound, and a gain of
-3dB halves the amplitude, and this is confirmed perceptually.
The decibel does not have a unit, since it expresses a ratio of two quantities with the same
unit of measurement.
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15.26 Dithering
Dithering is the technique of adding small quantities of noise to a signal to reduce the
audibility of low level distortion in a digital recording. A small amount of random noise is
added to the analog signal before the sampling stage, reducing the effect of "quantization
errors".
Note that dithering should always be applied after the output bus fader stage.
UV22HR Dithering
Quantization
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15.27 DVD-A
DVD-Audio (DVD-A) is a digital format for delivering high-fidelity audio content on a DVD.
Audio on a DVD-A disk can be stored in many different bit-depth, sampling rate and chan-
nel combinations - from 16-, 20- or 24-bit depth, at 44.1 to 96kHz sampling rates, in mono,
stereo and various surround channel combinations, including 5.1 channel surround. The sam-
pling rate may be as high as 192kHz for stereo channels, and different bit-depth/sampling
WaveLab 7