1.6 NOTATIONAL CONVENTIONS
Unless otherwise specified, bit rates correspond to single-channel or monaural coding throughout this text. Subjective quality measurements are specified in terms of either the five-point mean opinion score (MOS, Table 1.3) or the 41-point subjective difference grade (SDG, Chapter 12, Table 12.1). Table 1.4 lists some of the symbols and notation used in the book.
MOS | Perceptual quality |
1 | Bad |
2 | Poor |
3 | Average |
4 | Good |
5 | Excellent |
Symbol/notation | Description |
t, n |
Time index/sample index |
ω, Ω |
Frequency index (analog domain, discrete domain) |
f(= ω/2π) |
Frequency (Hz) |
Fs, Ts |
Sampling frequency, sampling period |
x(t) ↔ X(ω) |
Continuous-time Fourier transform (FT) pair |
x(n) ↔ X(Ω) |
Discrete-time Fourier transform (DTFT) pair |
x(n) ↔ X(z) |
z transform pair |
s[.] |
Indicates a particular element in a coefficient array |
h(n) ↔ H(Ω) |
Impulse-frequency response pair of a discrete time system |
e(n) |
Error/prediction residual |
Transfer function consisting of numerator-polynomial and denominator-polynomial (corresponding to b-coefficients and a-coefficients) |
|
Predicted signal |
|
Quantization/approximation operator or estimated/encoded ... |
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