Audio Processing System Reducing Bit-Error Artifacts
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Solution Overview
Problem
Current digital audio systems fail to effectively reduce audible artifacts in decoded audio signals caused by bit errors, even after error detection and correction, often resulting in muted content to avoid these artifacts.
Innovation Solution
An audio processing system that combines left and right channels to derive sum and difference signals, converts these to the frequency domain, and uses a noise reference derived from the difference signal to reduce noise artifacts through spectral subtraction, while controlling the processing with a quality-related control signal to distinguish between noise and signal content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error concealment strategies are applied to improve decoded audio signals, then audio quality is improved, but audible artifacts are still present
Solution Approach 1:
The patent segments the stereo signal into sum and difference components, processes them separately through different filtering paths, and then recombines them. This segmentation allows targeted noise reduction on the difference channel without affecting the sum channel, resolving the contradiction between maintaining audio quality and removing artifacts.
Solution Approach 2:
The patent introduces an intermediary processing stage where the difference signal is filtered through a noise reduction filter before being recombined with the sum signal. This intermediary process removes artifacts from the difference component while preserving the overall audio quality, effectively mediating between the conflicting requirements.
2Object-affected harmful factors
If content is muted to avoid audible artifacts, then artifacts are eliminated, but audio content is lost
Solution Approach 1:
The patent extracts the artifact-containing difference signal from the stereo pair, applies noise reduction filtering to remove artifacts, and then reinserts the cleaned difference signal. This extraction approach removes only the harmful artifacts while preserving the underlying audio content, avoiding the need to mute the entire signal.
Solution Approach 2:
The patent applies different processing qualities to different signal components: the sum signal is processed with minimal filtering to preserve content, while the difference signal undergoes aggressive noise reduction to remove artifacts. This local quality differentiation resolves the contradiction by treating each component according to its specific needs.
3Reliability
If left and right channels are processed independently, then channel-specific errors are handled, but artifacts remain in the decoded signal
Solution Approach 1:
The patent merges the independently processed sum and difference signals after the difference signal has undergone noise reduction filtering. This combining approach allows the benefits of independent error handling to be preserved while adding artifact reduction to the difference component, resolving the contradiction between independent processing and artifact elimination.
Data Source
AI summary
Systems and method for audio processing are disclosed. Left and right channels of an audio data stream are combined to derive sum and difference signals. A time domain to frequency domain converter is provided for converting the sum and difference signals to the frequency domain. a first processing unit is provided for deriving a frequency domain noise signal based at least partly on the frequency domain difference signal. A second processing unit is provided for processing the frequency domain sum signal using the noise signal thereby to reduce noise artifacts in the sum signal. A frequency domain to time domain converter is provided for converting at least the processed frequency domain sum signal to the time domain.