A Few Digital Audio Topics - Jan 17, 2001

By: Randy Mandsen - Revised: 2006-07-13 devin


Information about sampling rate, bit resolution, audio frequency spectrum, and compression types/algorithms.

Common Terms

Sampling Rate
Referred to in Samples per second: number of time a signal can be measured with known values.

Bit Resolution
Number of known values from which a sample value can be assigned: counted in binary (CD audio is 16 Bit - 65536 values)

Audio Frequency Spectrum
Generally referred to as 20 Hz. to 22 Khz. (an average adult human ear has a range up to 18 - 20 Khz)

Compression Types and Algorithms
Most compression uses a form of lossy (loses data) compression using psycho-acoustic principles to determine what data to throw away

MPEG 1, MPEG 2 (layers II, III ->mp3), MPEG 4, Windows Media, Real, Qdesign (based on MPEG) -> QuickTime, Quallcom PureVoice

Most of these algorithms use slow compression and fast decompression.

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