Apple Final Cut Pro 7 - Manual (Page 840)

When used Audio sample rates
A multiple of 48 and 96 kHz, this is a very high-resolution sample
rate used mostly for professional music recording and mastering. 192 kHz
Bit Depth
Unlike analog signals, which have an infinite range of volume levels, digital audio samples
use binary numbers (bits) to represent the strength of each audio sample. The accuracy
of each sample is determined by its bit depth. Higher bit depths mean your audio signal
is more accurately represented when it is sampled. Most digital audio systems use a
minimum of 16 bits per sample, which can represent 65,536 possible levels (24-bit samples
can represent over 16 million possible levels).
To better understand bit depth, think of each digital audio sample as a ladder with equally
spaced rungs that climb from silence to full volume. Each rung on the ladder is a possible
volume that a sample can represent, while the spaces between rungs are in-between
volumes that a sample cannot represent.
When a sample is made, the audio level of the analog signal often falls in the spaces
between rungs. In this case, the sample must be rounded to the nearest rung. The bit
depth of a digital audio sample determines how closely the rungs are spaced. The more
rungs available (or, the less space between rungs), the more precisely the original signal
can be represented.
Quantization errors occur when a digital audio sample does not exactly match the analog
signal strength it is supposed to represent (in other words, the digital audio sample is
slightly higher or lower than the analog signal). Quantization errors are also called rounding
errors because imprecise numbers represent the original analog audio. For example,
suppose an audio signal is exactly 1.15 volts, but the analog-to-digital converter rounds
this to 1 volt because this is the closest bit value available. This rounding error causes
noise in your digital audio signal. While quantization noise may be imperceptible, it can
potentially be exacerbated by further digital processing. Always try to use the highest
bit depth possible to avoid quantization errors.
The diagram on the far right shows the highest bit depth. Therefore, the audio samples
more accurately reflect the shape of the original analog audio signal.
Analog waveform Audio sample
840 Chapter 52 Audio Fundamentals