Method for computing nonlinear function in inverse quantization formula

Abstract

A method for calculating nonlinear function in counter quantization formula includes counting distribution probability of quantized spectral coefficient in code stream , calculating nonlinear function with table looking - up method in scope that occurrence probability of quantized spectral coefficient is relatively concentrated , using polynomial approximation to calculate nonlinear function is scope that occurrence probability of spectral coefficient is not relatively concentrated.

Description

technical field [0001] The invention relates to the field of audio compression algorithms, in particular to a method for calculating nonlinear functions in inverse quantization formulas. technical background [0002] AAC (Advanced Audio Coding) is a new audio compression algorithm formulated by the ISO MPEG organization in the MPEG-2 compression standard, which was further enhanced in the MPEG-4 standard later. AAC and MP3 algorithm are not compatible with each other. Compared with MP3 algorithm, AAC adopts some new encoding tools. Therefore, under the same compression quality, AAC has a higher compression ratio than MP3. When an AAC decoder is implemented on a hardware device, usually the device only supports fixed-point operations and does not support floating-point operations due to power consumption and cost reasons. figure 1 The structure diagram of the AAC decoder is given. When the decoder is implemented on a fixed-point device, since the inverse quantization formula...

AI Technical Summary

Problems solved by technology

[0021] If f: [a, b] → R is a continuous function defined in the closed interval [a, b], ε > 0, then there is a polynomial function P ε (x), such that |f(x)-P ε (x)|<εx∈[a,b] The disadvantage of polynomial approximation is that when the order of the polynomial is high, the calculation overhead is large

Images