Audio Encoding Initial Value Estimation for Quantization Loop
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Solution Overview
Problem
Existing audio encoding methods require heavy calculation due to significant differences between initial and expected values of iterative variables, such as scalefactors and global gain, during the quantization iterative loop process, leading to inefficiency.
Innovation Solution
The proposed audio encoding method estimates initial values of scalefactors and global gain based on frequency samples and masking curves, partitioning the frequency domain into scalefactor bands, and performing a quantization iterative loop encoding process using these values to generate a coded frame, thereby reducing the need for heavy calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If initial values of iterative variables (scalefactors and global gain) are set to zero, then the encoding process follows a standard procedure, but heavy calculation is required due to significant differences between initial and expectation values
Solution Approach 1:
The patent applies preliminary action by pre-calculating and setting initial values of scalefactors and global gain based on frequency sample energies before the quantization iterative loop begins. This preliminary estimation avoids the need for heavy calculations during the iterative process by starting closer to the expected final values, thereby improving encoding efficiency while reducing computational demand.
2Loss of time
If initial values of scalefactors and global gain are estimated based on frequency samples, then calculation efficiency is improved, but the complexity of determining initial values increases
Solution Approach 1:
The patent performs preliminary estimation of initial values by calculating frequency sample energies and using these to initialize scalefactors and global gain before the iterative loop. This preliminary action reduces the number of iterations needed while keeping the estimation complexity manageable through systematic calculations based on frequency domain characteristics.
Solution Approach 2:
The patent changes the parameter values of initial scalefactors and global gain from fixed zero values to dynamically estimated values based on frequency sample energies. This parameter change allows the encoding process to start from more accurate initial conditions, reducing iterative loop time while the estimation complexity is controlled through structured parameter calculation methods.
Data Source
AI summary
An audio encoding method previously estimates better initial iterative values of global-gain and scalefactor for avoiding heavy calculation. The estimating process of the encoding method includes calculating the bit allocation of one frequency sample based on a sampling rate, a bit rate, and the number of audio channels according to an input frame, and the psychoacoustic model, searching one frequency sample having the greatest sample energy in each of a plurality of scalefactor bands, quantizing the frequency sample to comply with the bit allocation and to generate a corresponding scalefactor, searching a maximum scalefactor of all scalefactor bands corresponding to the input frame, and setting initial values of scalefactors and an initial value of global-gain for the quantization iterative loop process according to the corresponding scalefactor and the maximum scalefactor.