Portable Audio Loudness Normalization With Adaptive Gain Limiting

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Solution Overview

Problem

Portable devices struggle to consistently reproduce high-quality audio with consistent loudness and intelligibility across varying media formats and content types, due to limitations in existing audio encoding and decoding standards.

Innovation Solution

The proposed solution involves a method for encoding and decoding audio signals that includes dynamic range compression and gain-limiting techniques, allowing for improved loudness and intelligibility on portable devices. This is achieved through the use of metadata that specifies dynamic range compression profiles and reference reproduction levels, which are adapted during decoding to optimize audio playback on portable devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing audio encoding and decoding standards are used, then audio content can be played back on portable devices, but consistent loudness and intelligibility cannot be achieved across varying media formats and content types

Engineering Contradiction:

Improveconsistent loudness and intelligibilityVSAvoidcompatibility with varying media formats and content types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies preliminary action by embedding metadata during the audio encoding stage that specifies dynamic range compression profiles and reference reproduction levels. This pre-prepared information allows portable devices to automatically adjust playback parameters without requiring content specifically prepared for these devices, resolving the contradiction between reliability and adaptability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes parameter changes by dynamically adjusting dynamic range compression and reference reproduction level parameters during decoding based on the embedded metadata. This allows the system to adapt audio playback parameters to ensure consistent loudness and intelligibility across different media formats and content types while maintaining compatibility

Inventive Principle:

Principle #35Parameter changes

2Reliability

If dynamic range compression and gain-limiting techniques are applied, then loudness and intelligibility are improved on portable devices, but additional processing complexity is introduced

Engineering Contradiction:

Improveloudness and intelligibilityVSAvoidencoding and decoding processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary metadata structure that carries dynamic range compression profile and reference reproduction level information between encoding and decoding stages. This intermediary approach simplifies the overall system by pre-calculating and embedding adjustment parameters, reducing the real-time processing complexity on portable devices while maintaining improved loudness and intelligibility

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250078849A1System and method for non-destructively normalizing loudness of audio signals within portable devices

Publication Date: 2025.03.06 DOLBY LABORATORIES LICENSING CORP

AI summary

Many portable playback devices cannot decode and playback encoded audio content having wide bandwidth and wide dynamic range with consistent loudness and intelligibility unless the encoded audio content has been prepared specially for these devices. This problem can be overcome by including with the encoded content some metadata that specifies a suitable dynamic range compression profile by either absolute values or differential values relative to another known compression profile. A playback device may also adaptively apply gain and limiting to the playback audio. Implementations in encoders, in transcoders and in decoders are disclosed.