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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.

APPENDIX B

GLOSSARY