Audio Limiter Backward Gain Contours for Low-Latency Clipping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio signal processing methods face challenges in mitigating hard clipping, which can lead to harsh sounds and damage to audio circuitry, while introducing latency or modifying non-clipped signal portions with soft clipping strategies.
Innovation Solution
The method employs a soft limiting function using block-wise oversampling to determine dynamic gain values, applying instant gain ascent and smooth gain decay through backward and forward passes to generate gain contours that prevent signal clipping without additional latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a delay is introduced into the audio signal to look ahead and dynamically adjust attenuation, then hard clipping is mitigated, but latency increases causing signal degradation and reduced interactivity
Solution Approach 1:
The patent applies preliminary action by performing a backward pass through the audio signal to pre-calculate gain values before the forward pass processing. This allows the system to anticipate peak levels and prepare appropriate attenuation without introducing additional latency, as the gain values are computed in advance during the backward traversal of the signal block.
2Object-generated harmful factors
If soft clipping with wave shaping function is used to avoid hard clipping, then distortion is reduced and sound quality improves, but non-clipped signal portions are modified
Solution Approach 1:
The patent implements dynamics by using time-varying gain contours that adapt to the signal characteristics. Instead of applying a static wave shaping function that modifies all signals, the system dynamically adjusts gain values based on the backward-pass analysis, applying attenuation only where and when needed to prevent clipping while preserving the integrity of non-clipped portions.
3Reliability
If block-wise oversampling is used for soft limiting, then clipping is prevented without additional latency, but processing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the audio signal into discrete blocks and processing each block independently through backward and forward passes. This block-wise approach allows the system to manage processing complexity efficiently while maintaining real-time performance, as each block can be processed in isolation using the oversampled data already available from the block-wise oversampling scheme.
Data Source
AI summary
Disclosed are systems and methods for processing an audio signal. In particular, there is provided a method for determining dynamic gain values to be applied on a digital input signal. The digital signal may be arranged in blocks. The dynamic gain values may be used for attenuating input signal values exceeding a clipping threshold. More particularly, the method comprising, for each signal block, passing backwards over the next signal block and the current signal block to produce a preliminary gain contour from the input signal; and passing forwards over the current signal block to produce a final gain contour for the current signal block based on the preliminary gain contour, wherein the gain contours are produced by applying an instant gain ascent and a smooth gain decay to the gain contours.