Loudness Metadata Mapping for Consistent Single-Mode Playback
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Solution Overview
Problem
Existing multimedia devices face challenges in providing consistent audio leveling across varying listening environments and diverse audio formats, due to factors like dynamic range compression and the lack of standardized metadata.
Innovation Solution
The method involves using encoder-generated metadata to perform dynamic range control and loudness normalization in audio decoding operations, converting between different loudness measurement standards like ITU-R BS.1770 and Replay Gain using reversible relations, and storing these values in metadata associated with audio signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic range compression is applied to normalize audio levels, then consistent playback level is achieved, but the dynamic range of the audio content is reduced
Solution Approach 1:
The patent applies dynamic range compression during the encoding stage rather than during playback. The encoder pre-processes the audio content to compress the dynamic range and normalize levels, storing the compressed audio and associated metadata. This preliminary action allows the decoder to play back audio at consistent levels without applying additional compression that would further reduce dynamic range.
Solution Approach 2:
The patent changes the parameter of dynamic range compression from being applied at playback to being applied at encoding. By adjusting when the compression occurs in the audio processing chain, the system achieves consistent playback levels while preserving the original dynamic range characteristics in the source material, which can be utilized in different playback modes.
2Reliability
If loudness normalization is implemented across all audio formats, then consistent audio leveling is achieved, but computational complexity increases
Solution Approach 1:
The patent calculates and stores loudness metadata during the encoding stage for various audio formats. The encoder analyzes the audio content and pre-computes loudness values and normalization parameters, storing them alongside the audio data. During playback, the decoder simply retrieves and applies these pre-computed values, avoiding the need for complex real-time loudness analysis and reducing computational complexity at the playback device.
3Adaptability or versatility
If multiple loudness measurement standards are supported, then compatibility with existing metadata standards is achieved, but conversion between standards increases processing requirements
Solution Approach 1:
The patent introduces a conversion mechanism that acts as an intermediary between different loudness measurement standards (e.g., ITU-R BS.1770 and Replay Gain). The system includes conversion tables or algorithms that map values from one standard to another, allowing the decoder to work with a primary standard while maintaining compatibility with devices or metadata formats that use alternative standards. This intermediary conversion layer enables multi-standard support without requiring the entire system to process all standards simultaneously.
Data Source
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AI summary
The present document relates to processing of multimedia data, notably the encoding, the transmission, the decoding and the rendering of multimedia data, e.g. audio files or bitstreams. In particular, the present document relates to the implementation of loudness control in multimedia players. A method for providing loudness related data to a media player is described. The method comprises the steps of providing a first loudness related value associated with an audio signal; wherein the first loudness related value has been determined according to a first procedure; of converting the first loudness related value into a second loudness related value using a reversible relation; wherein the second loudness related value is associated with a second procedure for determining loudness related values; of storing the second loudness related value in metadata associated with the audio signal; and of providing the metadata to the media player.