Block Audio Limiter Using Frame Gain to Reduce Distortion
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Solution Overview
Problem
Conventional audio limiting techniques perform processing sample-by-sample, leading to increased computational costs and audible distortion due to oscillations in gain values, as they apply multiple gain curves to individual audio samples, causing acoustic distortion and inefficiency.
Innovation Solution
Implementing block-based audio limiting, where a single gain curve is applied to a block of audio samples, determining a block gain value based on the maximum amplitude across all channels, and selecting between attack, hold, or release processing to ensure the audio signal remains below a threshold, reducing processing consumption and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sample-by-sample audio limiting processing is performed, then audio signal attenuation can be applied to prevent clipping, but computational cost increases and audible distortion occurs due to oscillations in gain values
Solution Approach 1:
The patent divides the audio signal processing into blocks of multiple samples rather than processing individual samples. Each block is processed together using a single gain curve determined from the maximum amplitude within that block, reducing the number of gain calculations from one per sample to one per block.
Solution Approach 2:
The patent combines multiple sample processing operations into a single block-level operation. By determining one gain curve for the entire block based on the maximum amplitude across all samples in that block, multiple individual processing steps are merged into a single efficient operation.
2Reliability
If multiple gain curves are applied to individual audio samples, then audio clipping is prevented, but acoustic distortion increases due to oscillations in gain values
Solution Approach 1:
The patent segments the audio signal into blocks and applies a single gain curve to each block rather than multiple gain curves to individual samples. This segmentation approach eliminates the oscillations in gain values that cause acoustic distortion while maintaining effective clipping prevention.
Solution Approach 2:
The patent performs preliminary determination of the maximum amplitude within each block before applying the gain curve. By identifying the peak amplitude in advance and calculating the appropriate gain based on that maximum value, the system avoids subsequent oscillations in gain application that would cause distortion.
3Measurement precision
If sample-by-sample processing is used, then precise audio control is achieved, but processing efficiency decreases
Solution Approach 1:
The patent segments audio processing into blocks while maintaining precision by determining the maximum amplitude within each block and calculating the gain curve based on that maximum. This approach preserves audio control precision at the block level while significantly improving processing efficiency compared to sample-by-sample processing.
Solution Approach 2:
The patent changes the processing parameter from individual sample level to block level. By processing multiple samples within a block using a single gain curve determined from the block's maximum amplitude, the system achieves both precision (through maximum-based gain calculation) and efficiency (through reduced processing operations).
Data Source
AI summary
A system configured to perform audio limiting using block-based processing to reduce acoustic distortion and/or computational cost. While sample-by-sample processing would apply a plurality of gain ramps to a single audio sample, the block-based processing applies a single gain ramp to ensure that the audio sample is below a threshold value. To perform block-based processing, an audio limiter component identifies a maximum amplitude value across all channels for a selected audio frame of an audio signal. Using the maximum amplitude value and the threshold value, the audio limiter component determines a block gain value associated with the selected audio frame and selects between attack processing, hold processing, or release processing. Using the selected processing and the block gain value, the audio limiter component determines instantaneous gain values for the audio samples within the audio frame.