Audio Encoding Parameters for HF Tonality Mismatch Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio coding technologies face issues with tonality mismatch and perceptual artifacts due to spectral fine structure differences between high-frequency and low-frequency bands, particularly in bandwidth extension and intelligent gap filling methods, leading to annoying noise bursts and instability.
Innovation Solution
A novel approach that analyzes both the source and target spectral bands to calculate a compensation value, adjusting parameters based on psychoacoustic models to minimize perceptual annoyance by damping problematic spectral regions, thereby reducing tonality mismatch and enhancing perceptual quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spectral patching is used to reconstruct the HF spectral region, then bandwidth extension is achieved, but tonality mismatch occurs leading to perceptual artifacts
Solution Approach 1:
The patent applies local quality by differentiating between tonal and non-tonal spectral regions. The analyzer detects tonality characteristics in both source and target bands, and the compensator applies selective compensation only to regions exhibiting tonality mismatch. This ensures that perceptual artifacts are reduced in problematic regions while preserving the bandwidth extension benefit in regions where patching is appropriate.
Solution Approach 2:
The patent changes parameters by calculating a compensation value that adjusts the spectral envelope based on detected tonality characteristics. The compensator modifies the gain factor or spectral envelope parameters in the target band to match the tonality of the source band, thereby reducing perceptual artifacts while maintaining the bandwidth extension functionality.
2Loss of information
If bandpass noise is scaled up to replace tonal content, then spectral holes are filled, but annoying noise bursts occur
Solution Approach 1:
The patent changes parameters by using the detected tonality characteristics to control the scaling factor applied to bandpass noise. When tonality mismatch is detected, the compensator reduces the scaling factor or applies selective attenuation to prevent noise bursts. This parameter adjustment ensures that spectral holes are filled appropriately without generating perceptually annoying artifacts.
3Stability of the object's composition
If artificial replacement sinusoids are inserted to address tonality mismatch, then tonal stability improves, but additional side information increases bit demand
Solution Approach 1:
The patent extracts the essential tonality characteristics by analyzing and comparing spectral features between source and target bands. Instead of transmitting full spectral data or multiple side information parameters, the system extracts only the necessary tonality detection results and compensation values. This extraction approach maintains tonal stability while minimizing the additional bit demand, as only compact representation of tonality characteristics and compensation factors need to be transmitted.
4Measurement precision
If spectral envelope is adjusted to match original HF signal, then spectral fidelity improves, but tonality mismatch persists
Solution Approach 1:
The patent applies local quality by treating the spectral envelope adjustment and tonality matching as separate, localized operations. The analyzer first detects tonality characteristics in specific frequency regions, then the compensator applies targeted compensation only to regions exhibiting tonality mismatch. This allows the spectral envelope to maintain high accuracy overall while locally correcting tonality issues where they occur.
Solution Approach 2:
The patent applies preliminary action by performing tonality detection and compensation calculation before final spectral reconstruction. The analyzer detects tonality characteristics in advance, the compensator calculates the necessary compensation values, and only then is the spectral envelope applied. This preliminary processing ensures that tonality mismatch is addressed proactively rather than reactively, improving both spectral fidelity and tonal accuracy.
Data Source
AI summary
An apparatus for encoding an audio signal includes: a core encoder for core encoding first audio data in a first spectral band; a parametric coder for parametrically coding second audio data in a second spectral band being different from the first spectral band, wherein the parametric coder includes: an analyzer for analyzing first audio data in the first spectral band to obtain a first analysis result and for analyzing second audio data in the second spectral band to obtain a second analysis result; a compensator for calculating a compensation value using the first analysis result and the second analysis result; and a parameter calculated for calculating a parameter from the second audio data in the second spectral band using the compensation value.