Audio Loudness Normalization Using Metadata Distribution
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Solution Overview
Problem
The challenge lies in effectively adjusting and normalizing the output loudness level of audio content across different contents, as existing methods struggle to maintain consistent loudness levels due to varying intended loudness settings, leading to user inconvenience in volume control.
Innovation Solution
An audio signal processing method that receives metadata with loudness distribution information, allowing for variable-length encoding of loudness ratios and applying nonlinear processing like dynamic range control to adjust the loudness based on target levels, ensuring consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If content creators increase the volume of audio signals to improve perceived sound quality, then sound quality is improved, but loudness differences occur between contents requiring frequent volume adjustments
Solution Approach 1:
The system measures the loudness of the audio signal using loudness distribution information from metadata, compares it with a target loudness level, and automatically adjusts the volume based on the difference. This closed-loop feedback mechanism eliminates the need for manual volume adjustments while maintaining consistent perceived sound quality across different contents.
Solution Approach 2:
The audio playback system automatically normalizes loudness by utilizing loudness distribution information embedded in the metadata. The system self-adjusts the volume based on the measured loudness characteristics of each content, eliminating the need for user intervention and ensuring consistent listening experience across different audio contents.
2Adaptability or versatility
If different loudness settings are applied to different audio contents during production, then intended loudness can be optimized for each content, but user convenience deteriorates due to frequent volume adjustments
Solution Approach 1:
Loudness distribution information is pre-calculated and embedded in the metadata during content production. This preliminary action allows the playback system to automatically retrieve and apply the appropriate loudness characteristics without requiring real-time measurement or user adjustment, thus maintaining both content-specific optimization and user convenience.
Solution Approach 2:
The system dynamically changes the volume parameter based on the loudness distribution information from metadata. By automatically adjusting the gain parameter according to the measured loudness characteristics of each content, the system adapts to different contents while maintaining consistent perceived loudness, eliminating the need for frequent manual volume adjustments.
3Ease of operation
If loudness normalization techniques are applied to maintain consistent volume levels, then user convenience is improved, but the ability to preserve intended loudness characteristics of different contents is reduced
Solution Approach 1:
The loudness distribution information is pre-calculated and stored in metadata during content production, preserving the intended loudness characteristics. During playback, the system retrieves this pre-computed information and uses it to automatically adjust volume, thus maintaining both the original artistic intent and consistent user experience without losing either aspect.
Data Source
AI summary
Disclosed is a method of operating an audio signal processing apparatus playing content including an audio signal. The method includes receiving the audio signal, receiving metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of the audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal, and adjusting the loudness of the audio signal based on the metadata.