Audio Metadata Correction for Consistent Loudness Playback

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Solution Overview

Problem

Existing audio playback systems face challenges in maintaining consistent loudness and dynamic range due to misuse or misunderstanding of metadata, leading to excessive variations in audio volume during broadcasts and recordings.

Innovation Solution

A method that analyzes decoded audio information to derive a second loudness normalization level and estimate the compression profile, generating an output signal with corrected metadata to adjust playback loudness and dynamic range, ensuring consistent listening experiences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If metadata is used to control playback loudness and dynamic range, then loudness consistency is improved, but metadata misuse or misunderstanding causes excessive variations in playback loudness

Engineering Contradiction:

Improveloudness consistencyVSAvoidmetadata accuracy

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The system measures the actual loudness of decoded audio information and compares it with the target loudness level indicated by metadata. Based on this feedback, the system automatically adjusts playback signal levels to achieve consistent loudness across different audio sources, compensating for metadata misuse or inaccuracies.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The playback system performs self-adjustment by automatically analyzing its own output and correcting loudness variations without requiring external intervention or perfect metadata. The system serves itself by monitoring and regulating its playback levels based on actual measured loudness rather than relying solely on provided metadata.

Inventive Principle:

Principle #25Self-service

2Stability of the object's composition

If automatic loudness control is implemented, then playback consistency is improved, but system complexity increases

Engineering Contradiction:

Improveplayback consistencyVSAvoidsystem complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system replaces manual volume adjustment mechanisms with automatic digital signal processing. A processor automatically analyzes decoded audio information, measures loudness, and adjusts playback levels through digital gain control, eliminating the need for manual mechanical volume adjustments and reducing operational complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The playback system integrates multiple functions into a single processing chain: decoding, loudness measurement, metadata interpretation, and automatic level adjustment. This multi-functional approach consolidates what would otherwise require separate devices or manual operations into one unified system, managing complexity through integration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7617109B2Method for correcting metadata affecting the playback loudness and dynamic range of audio information

Publication Date: 2009.11.10 DOLBY LABORATORIES LICENSING CORP

AI summary

A coded signal conveys encoded audio information and metadata that may be used to control the loudness and dynamic range of the audio information during its playback. If the values for these metadata parameters are set incorrectly, annoying fluctuations in loudness during playback can result. The present invention overcomes this problem by detecting incorrect metadata parameter values in the signal and replacing the incorrect values with corrected values.