Compressed Audio Restoration Using Harmonic and Spatial Enhancement
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Solution Overview
Problem
Compressed audio signals often suffer from undesirable audible differences due to data compression, which discards perceptually less important components, leading to reduced quality, especially at lower bitrates.
Innovation Solution
The Signal Enhancer system modifies compressed audio signals by restoring and enhancing discarded or altered components, such as bandwidth, harmonics, transients, reverb, and masked signals, while phase-aligning harmonic components, operating on individual spatial slices and Mid-Side components of stereo signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data compression is applied to reduce audio signal size, then storage and transmission efficiency is improved, but audible quality deteriorates due to discarded signal components
Solution Approach 1:
The patent applies the principle of discarding and recovering by first identifying and discarding inaudible signal components during compression, then recovering and reconstructing the discarded audible components through analysis of the compressed signal and synthesis of missing harmonics, transients, and spatial information. This allows the system to achieve compression while restoring the perceived audio quality.
Solution Approach 2:
The patent uses an intermediary approach by introducing a perceptual model as a mediator between the compressed signal and the final output. This perceptual model analyzes the compressed signal to identify missing components and guides the reconstruction process, acting as an intermediary that translates compressed data back into perceptually accurate audio.
2Quantity of substance
If perceptual audio codec discards less important components, then data rate is reduced, but perceived audio quality deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the perceptual parameters of the audio signal during reconstruction. It adjusts parameters such as harmonic content, transient characteristics, and spatial distribution to match the original perceived quality while maintaining reduced data rates. The system changes parameters like bandwidth extension and reverb characteristics to restore quality.
3Loss of information
If compression artifacts are reduced by maintaining more signal components, then audio quality is improved, but compression efficiency deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the audio signal into different perceptual components (harmonics, transients, reverb, spatial information) and processing each segment separately. This allows selective reconstruction of only the necessary components for perceived quality, maintaining compression efficiency while restoring audio fidelity through targeted component recovery.
Data Source
AI summary
A system for processing compressed audio includes a signal enhancer module configured to generate one or more signal treatments. The one or more signal treatments may be generated by the signal enhancer module based on analysis of the incoming audio signal. Alternatively, or in addition, characteristics of the incoming audio signal may be provided to the signal enhancer module for use in generating the one or more signal treatments. The one or more signal treatments may be added to file audio signals.