Audio Clip Detection Using Peak-Referenced Differentiator Signals
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Solution Overview
Problem
Existing audio signal clipping detection methods are inadequate when the maximum unclipped output signal level from an audio source is unknown, as they rely on predetermined reference voltages and cannot effectively detect clipping in such scenarios.
Innovation Solution
An audio signal clip detector system that includes a peak hold circuit, differentiator, and comparator to generate a peak reference signal, differentiate and rectify the audio signal, and compare it to the peak reference signal to produce a clip detect signal, indicating whether the audio signal is clipped, without relying on predetermined voltage limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If predetermined reference voltage methods are used for clip detection, then the detection system is simple and reliable, but it cannot detect clipping when the maximum unclipped output level is unknown
Solution Approach 1:
The system uses the audio signal itself to generate the reference voltage through peak detection, eliminating the need for external predetermined reference voltages. The peak detector circuit automatically captures the maximum voltage of the input signal and uses it as the comparison reference, allowing the system to adapt to any unknown signal level while maintaining reliable clipping detection
Solution Approach 2:
The reference voltage is dynamically changed based on the input signal characteristics. Instead of using a fixed predetermined voltage, the system continuously monitors the peak voltage of the audio signal and adjusts the reference voltage accordingly, enabling the detection system to work with any unknown maximum output level
2Measurement precision
If the audio signal is directly compared without differentiation, then the detection circuit is simpler, but it cannot accurately detect the onset of clipping
Solution Approach 1:
The audio signal is pre-processed through differentiation and rectification before comparison with the peak reference voltage. This preliminary action transforms the signal to emphasize the transition points where clipping occurs, allowing the comparator to accurately detect the onset of clipping by comparing the rectified differentiated signal against the peak voltage threshold
Data Source
AI summary
Methods and apparatus for audio signal clip detection are disclosed. The clip detectors may receive audio signals, from which peak reference signals, indicative of the highest voltage of the received audio signals, may be derived. The received audio signals may also be differentiated and phase-lagged to produce differentiated audio signals which may, in turn, be rectified to produce rectified differentiator signals. The rectified differentiator signals and the peak reference signals may be compared to thereby produce clip detect signals indicative of whether the received audio signals are clipped. The clip detect signals may then be used to indicate whether the received audio signal are clipped.