Multi-Band Audio CODEC Gain Control Using Envelope Detection

Solution Overview

Problem

Conventional audio processing systems face challenges in effectively managing multi-band amplitude estimation and gain control, particularly in duplex operations where simultaneous audio input and output are required, leading to sub-optimal audio quality and resource management.

Innovation Solution

A method and system for multi-band amplitude estimation and gain control in an audio CODEC, which filters and delays audio signals to generate sub-band signals, applies gain based on detected amplitudes using an envelope detector and subjective loudness curves, and adjusts gain incrementally to maintain target values, optimizing audio output for various devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional audio processing systems are used for duplex operations, then basic audio input and output functionality is provided, but audio quality is sub-optimal and resource management is inefficient

Engineering Contradiction:

Improveaudio qualityVSAvoidresource management efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The audio signal is divided into multiple frequency bands using bandpass filters. Each band is processed independently with its own gain control, allowing optimized handling of different frequency components while maintaining overall audio quality and resource efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically adjusts gain values for each frequency band based on real-time amplitude detection. The gain control adapts to changing audio conditions, improving audio quality while efficiently managing processing resources through adaptive rather than static processing.

Inventive Principle:

Principle #15Dynamics

2Reliability

If multi-band processing is implemented to improve audio quality, then aurally pleasing output is achieved, but system complexity increases

Engineering Contradiction:

Improveaudio qualityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The audio signal is divided into multiple frequency bands using bandpass filters. Each band is processed independently with its own gain control, allowing optimized handling of different frequency components while maintaining overall audio quality and resource efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system uses envelope detectors to monitor the amplitude of each frequency band and feeds this information back to the gain control mechanism. This feedback loop enables automatic gain adjustment based on actual signal conditions, achieving high audio quality without requiring complex manual control systems.

Inventive Principle:

Principle #23Feedback

3Weight of moving object

If resource-constrained portable devices are used, then portability is improved, but audio processing capability is limited

Engineering Contradiction:

Improvedevice portabilityVSAvoidaudio processing capability

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The audio signal is divided into multiple frequency bands using bandpass filters. Each band is processed independently with its own gain control, allowing optimized handling of different frequency components while maintaining overall audio quality and resource efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes processing parameters (gain values) for each frequency band based on detected amplitude levels. This parameter-based control enables efficient audio processing in resource-constrained environments by avoiding complex computational approaches while maintaining audio quality.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances audio quality by dynamically controlling gain across multiple frequency bands, ensuring aurally pleasing output while efficiently managing resources, even in resource-constrained portable devices.

Implementation Method 1

The gain may be controlled based on a detected amplitude of a summed signal derived by summing the particular one of the one or more sub-band signals and a corresponding one of the one or more level-adjusted sub-band signals. The amplitude of the summed signal may be detected utilizing an envelope detector.

Methodology Applied

Scientific EffectEnvelope detection:

Data Source

PatentUS8326640B2Method and system for multi-band amplitude estimation and gain control in an audio CODEC

Publication Date: 2012.12.04 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

Aspects of a method and system for multi-band amplitude estimation and gain control in an audio CODEC are provided. In this regard, an audio signal may be filtered and delayed to generate one or more sub-band signals, a gain may be applied to each sub-band signal to generate one or more level adjusted sub-band signals, and the one or more level adjusted signals may be added to a delayed version of the audio signal. The gain applied to a particular one of the one or more sub-band signals may be controlled based on a detected amplitude of a summed signal derived by summing the particular one of the one or more sub-band signals and a corresponding one of the one or more level-adjusted sub-band signals.