Adaptive Audio Gain Control for Consistent Media Stream Loudness
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Solution Overview
Problem
Existing digital volume normalization techniques for media streams are ineffective and introduce audible artifacts, leading to inconsistent perceived volume when switching between different media streams in place-shifting applications.
Innovation Solution
An adaptive gain control method that initializes processing with a fast gain adaptation scheme for initial normalization, followed by a steady state gain adaptation scheme to maintain consistent volume, using weighting factors to calculate and apply gain values to digital audio samples in a media stream, ensuring normalized volume across different media streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If existing digital volume normalization techniques are applied, then volume adjustment is automated, but audible artifacts are introduced and normalization effectiveness is reduced
Solution Approach 1:
The patent implements dynamic gain adjustment by continuously monitoring audio signal characteristics and adapting gain values in real-time based on signal strength and variability. This dynamic approach replaces static normalization methods, allowing the system to respond to changing audio conditions without introducing artifacts.
Solution Approach 2:
The system changes multiple parameters simultaneously including gain values, attack times, and release times based on the measured characteristics of the audio signal. By coordinating changes across multiple parameters rather than adjusting a single gain value, the system achieves effective normalization while maintaining audio quality.
2Stability of the object's composition
If gain adjustment is applied to normalize volume across different media streams, then perceived loudness consistency is improved, but audio quality may deteriorate due to artifacts
Solution Approach 1:
The patent employs feedback mechanisms where the output of the gain adjustment process is monitored and fed back to continuously refine the gain application. This closed-loop approach ensures that normalization is achieved while detecting and preventing artifact generation, maintaining both loudness consistency and audio quality.
Solution Approach 2:
The system applies gain adjustment selectively based on the measured characteristics of each audio segment rather than uniformly across all signals. By applying partial action only where needed and adjusting the degree of gain based on signal variability, the system achieves normalization without over-processing that would generate artifacts.
3Speed
If fast gain adaptation scheme is used for initial normalization, then normalization speed is improved, but steady state accuracy may be compromised
Solution Approach 1:
The patent divides the gain adaptation process into distinct phases: a fast adaptation phase for initial normalization and a steady-state phase for precise maintenance. This segmentation allows each phase to be optimized independently - the fast phase prioritizes speed while the steady-state phase prioritizes accuracy, resolving the contradiction between speed and precision.
Solution Approach 2:
The system performs preliminary fast gain adjustment to quickly bring audio levels into the acceptable range, then transitions to a more precise steady-state adjustment mode. This preliminary action approach allows the system to achieve rapid initial normalization followed by refined accuracy without compromising either speed or precision.
Data Source
AI summary
An adaptive gain control system and related operating method for digital audio samples is provided. The method is suitable for use with a digital media encoding system that transmits encoded media streams to a remotely-located presentation device such as a media player. The method begins by initializing the processing of a media stream. Then, the method adjusts the gain of a first set of digital audio samples in the media stream using a fast gain adaptation scheme, resulting in a first group of gain-adjusted digital audio samples having normalized volume during presentation. The method continues by adjusting the gain of a second set of digital audio samples in the media stream using a steady state gain adaptation scheme that is different than the fast gain adaptation scheme, resulting in a second group of gain-adjusted digital audio samples having normalized volume during presentation.