Graphic Equalizer Gain Limiting to Prevent Audio Clipping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Graphic equalizers struggle to prevent audio signal clipping and distortion when gains are set high, as the increased gains in adjacent bands interfere, making it difficult to determine the appropriate gain limit, leading to deformation of the audio signal waveform.
Innovation Solution
An audio processor with a Fourier transform unit, filtering unit, inverse Fourier transform unit, band gain setting unit, volume setting unit, first filter coefficient calculator, and second filter coefficient calculator that transforms audio signals into the frequency domain, performs filtering, and limits gains to prevent clipping by comparing and adjusting filter coefficients based on set gains and volume levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gain in any band is increased to maximize volume, then the volume level is improved, but the audio signal exceeds the full-scale value and overflows causing clipping and distortion
Solution Approach 1:
The patent performs preliminary calculation of the maximum allowable gain for each band based on the full-scale value and the sum of gains in adjacent bands before processing the audio signal. This advance computation prevents overflow by establishing safe gain limits that account for interference between adjacent bands, thereby maintaining signal integrity while maximizing volume.
2Adaptability or versatility
If the gain for respective bands is increased to improve frequency characteristics, then the frequency response is improved, but the total gain exceeds the full-scale value causing clipping
Solution Approach 1:
The patent applies different gain values to different frequency bands according to the user's equalizer settings, allowing optimization of frequency characteristics for each band. Simultaneously, it calculates the maximum allowable gain for each band by considering the full-scale value and the interference from adjacent bands, ensuring that local gain adjustments do not cause overall signal overflow.
3Reliability
If the maximum gain is set for all bands to prevent clipping, then signal integrity is maintained, but the volume level and frequency characteristics adjustability are reduced
Solution Approach 1:
The patent dynamically calculates the maximum allowable gain for each band based on the specific equalizer settings and the full-scale value, rather than applying a fixed maximum gain to all bands. This dynamic adjustment allows the system to maintain signal integrity while preserving the user's desired frequency characteristics and volume level, adapting the gain limits to the current processing conditions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An audio processor (1) includes a first filter coefficient calculator (31) that calculates a first filter coefficient so as to correspond to first gains for respective bands set by a user, a second filter coefficient calculator (32) that if values of third gains for respective bands of the first filter coefficient are greater than an absolute value of a second gain set by the user, calculates a second filter coefficient by limiting the values of the third gains for the respective bands to the amplitude value of the second gain, and a filtering unit (35) that filters an audio signal that has been transformed into a frequency-domain signal, using the second filter coefficient.