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APPENDIX B GLOSSARY
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Clipboard
The Clipboard is where data that you have cut or copied in Vegas software is stored. You can then paste the
data back into Vegas software at a different location, or paste it into other applications. Some data, such as
audio, cannot be pasted into applications such as Microsoft Word or Notepad, but the text data from the
Edit Details window can be pasted. This allows you to then print or format the data. The Video Preview
window also lets you capture still frames to the Clipboard for use in any image editing program. For more
information, see Understanding the Video Preview window on page 287.
Clipping
Clipping is what occurs when the amplitude of a sound is above the maximum allowed recording level. In
digital systems, clipping is seen as a clamping of the data to a maximum value, such as 32,767 in 16-bit data.
Clipping causes sound to distort.
Codec
An acronym for COmpressor/DECompressor. A codec is an computer algorithm that is used to compress
video and audio data, shrinking file sizes and data rates.
Compositing
Compositing is the term used to describe the way separate video sources are mixed together. Overlay titles
are composited onto a background video sequence.
Crossfade
Mixing two pieces of overlapping audio or video by fading one out as the other fades in.
Cutoff frequency
The cutoff frequency of a filter is the frequency at which the filter changes its response. For example, in a
low-pass filter, frequencies greater than the cutoff frequency are attenuated while frequencies less than the
cutoff frequency are not affected.
DC Offset
DC Offset occurs when hardware, such as a sound card, adds DC current to a recorded audio signal. This
current causes the audio signal to alternate around a point above or below the normal -infinity dB (center)
line in the sound file. To see if you have a DC offset present, you can zoom all the way into a sound file and
see if it appears to be floating over the center line.
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 software, 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 Microsoft Windows to connect different hardware and software. For example, a
sound card device driver is used by Microsoft Windows software to control sound card recording and
playback.