Audio Compressor Curves to Avoid Boosting Background Noise
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Solution Overview
Problem
Existing audio processing systems amplify unwanted background noise in non-professionally recorded audio, as they are designed for professionally produced content and struggle to differentiate between wanted and unwanted signals, leading to unpleasant amplification of ambient noise.
Innovation Solution
Implementing a dynamic range control (DRC) and automatic gain control (AGC) system that limits processing below a specified threshold level, using noise possibility values and auditory scene analysis to avoid boosting unwanted noise, and employing DRC compression curves with extra knees to prevent noise amplification, while maintaining consistent volume and sonic balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic range control (DRC) and automatic gain control (AGC) are applied to amplify low-level audio signals, then the volume consistency is improved, but unwanted background noise is amplified along with the desired audio
Solution Approach 1:
The patent applies different processing characteristics to different parts of the audio signal based on its content. By analyzing spectral skewness and noise possibility values, the system identifies whether low-level signals represent desired audio or unwanted noise, then applies appropriate gain control accordingly. This local differentiation allows volume consistency for desired signals while avoiding noise amplification.
Solution Approach 2:
The system dynamically changes processing parameters (gain amounts, compression curve characteristics) based on real-time analysis of the audio signal's spectral properties. By monitoring spectral skewness and noise possibility values, the system adjusts DRC/AGC parameters to maintain volume consistency when needed while preventing noise boosting when detected.
2Device complexity
If a single DRC compression curve is used for all audio content, then the system is simple to implement, but it cannot differentiate between professionally produced audio and non-professional recordings
Solution Approach 1:
The patent employs dynamic selection of DRC compression curves based on real-time analysis of the audio signal's spectral characteristics. The system calculates spectral skewness and noise possibility values to determine the appropriate compression curve, transitioning between different processing modes as needed. This dynamic adaptation provides both simplicity (automated selection) and versatility (multiple curve options).
Solution Approach 2:
The system uses feedback from spectral analysis (skewness calculation, noise possibility assessment) to automatically select the appropriate DRC compression curve. This closed-loop approach allows the system to adapt to different content types without manual intervention, maintaining simplicity while achieving content-aware processing.
Data Source
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AI summary
The processing of audio signals during playback is provided, so that audio signals that fall below a specified threshold loudness level are processed to avoid making unwanted background noise audible. N-channel audio is received from a playback volume controller/leveler (101). The level of the audio is compared with a threshold level. If the level is greater than the threshold level, the audio is processed with a first amount of gain in accordance with a first dynamic range control (DRC) compression curve that is tuned for professionally produced audio. If the level is less than or equal to the threshold level, the audio is processed with a second amount of gain in accordance with a second DRC compression curve that is designed to avoid boosting unwanted background noise. After applying the gain to the audio, the audio is sent to a downstream device.