Audio Error Concealment Using Signal-Adaptive Replacement Frames
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Solution Overview
Problem
Existing error concealment techniques for digital audio signals, such as muting, repetition, and interpolation, often result in noticeable artifacts like sudden changes, 'clicking' noises, and echo effects, especially during burst errors, and are not versatile enough for real-time communication systems.
Innovation Solution
A method that classifies speech or audio data into characteristics to generate replacement frames, using techniques like pitch computation, filterbank analysis, and extrapolation processing to minimize errors and smooth signal boundaries, reducing computation overhead and retransmission delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple error concealment techniques like muting or repetition are used, then the computation load is low and implementation is simple, but noticeable artifacts like sudden changes, clicking noises, and echo effects occur
Solution Approach 1:
The patent introduces an intermediary processing stage between error detection and simple replacement. Instead of directly applying muting or repetition, the system first processes the error frame through interpolation or extrapolation algorithms that generate intermediate replacement values. These intermediary values smoothly transition between the last valid frame and the replacement data, eliminating abrupt changes and clicking noises while keeping the overall system structure relatively simple.
Solution Approach 2:
The patent changes the parameters of the replacement data by dynamically adjusting interpolation factors, smoothing coefficients, and transition rates based on the specific error conditions and surrounding audio characteristics. This parameter adjustment allows the system to adapt the concealment strategy to minimize artifacts like echo effects and sudden changes while maintaining implementation feasibility.
2Object-affected harmful factors
If interpolation techniques are used to reconstruct replacement data, then better error concealment results are obtained compared to simple techniques, but computation load increases
Solution Approach 1:
The patent applies partial interpolation by selectively processing only the necessary frequency bands or time segments of the error frame rather than performing full-frame interpolation. The system identifies which portions of the audio signal require concealment and applies interpolation algorithms only to those regions, reducing overall computation load while maintaining adequate error concealment quality for the most critical parts of the signal.
Solution Approach 2:
The patent segments the audio signal into multiple frequency bands using filter banks, then applies different interpolation strategies to each band based on its characteristics. This segmentation allows the system to use computationally intensive interpolation methods only where necessary (e.g., in frequency bands with important audio content) while using simpler methods or skipping processing in less critical bands, thereby balancing quality and computation load.
3Object-affected harmful factors
If codec-dependent error concealment methods are used, then optimization for specific speech or audio codecs is achieved, but versatility across different codecs is reduced
Solution Approach 1:
The patent implements a universal error concealment framework that operates at the audio signal level rather than at the codec-specific parameter level. The system processes the decoded audio waveform directly using signal processing techniques like interpolation and extrapolation that are independent of the specific codec used. This multi-functional approach allows the same error concealment mechanism to effectively handle errors from various codecs (e.g., MP3, AAC, Opus) without requiring codec-specific optimization, thereby achieving both effectiveness and versatility.
Data Source
AI summary
The conventional error conceal processing generates a greatly fluctuating irregular sound which is unpleasant to ears and causes a remarkable echo effect and click noise. A notification signal detection unit (301) judges processing for an input frame. In case of an error frame, a sound detection unit (303) makes judgment whether a preceding non-error data frame is a sound signal. If it is a sound frame, a sound copying unit (304) generates a replacing frame. If it is a non-sound frame, a transient signal detection unit (305) judges whether it is an attack signal by the transient signal detection and selects an appropriate area from the preceding non-error frame.