Audio Loudness Metadata for Dynamic Range Control
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Solution Overview
Problem
The varying dynamic range and loudness levels of digital audio signals across different devices and playback environments lead to inconsistent user experiences, as existing technologies lack effective methods for real-time dynamic range control and loudness normalization.
Innovation Solution
The method involves applying an audio normalization gain value to an audio signal, computing dynamic range control (DRC) gain values based on predefined characteristics, and embedding these values as metadata with the encoded signal. During playback, the DRC gain values are adjusted using local parameters and metadata to ensure consistent loudness across different devices and environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If dynamic range control is applied to increase average loudness, then the average loudness is improved, but the peak levels must be reduced which causes clipping and audible distortion
Solution Approach 1:
The patent applies preliminary dynamic range control during the encoding stage to pre-adjust the audio signal's dynamic range. By computing DRC gain values and applying them before encoding, the system prepares the signal to fit within the desired envelope, preventing clipping and distortion during playback while maintaining consistent loudness across different devices and programs.
2Illumination intensity
If per-frame loudness calculations are performed to achieve loudness normalization, then the loudness consistency is improved, but the computational complexity and processing time increase
Solution Approach 1:
The patent computes loudness values and DRC gain values in advance during the encoding stage and embeds them as metadata with the encoded audio signal. This preliminary calculation eliminates the need for real-time per-frame loudness computations during playback, significantly reducing processing complexity while maintaining loudness normalization across different playback devices and environments.
3Manufacturing precision
If different audio processing settings are used for different devices, then the audio quality for each device is optimized, but the system complexity increases
Solution Approach 1:
The patent embeds device-specific audio processing parameters, including DRC gain values and loudness metadata, directly into the encoded audio signal. This allows different audio processing settings to be applied for different devices without increasing system complexity, as each device simply reads and applies the pre-configured parameters associated with its characteristics from the metadata.
Data Source
AI summary
An audio normalization gain value is applied to an audio signal to produce a normalized signal. The normalized signal is processed to compute dynamic range control (DRC) gain values in accordance with a selected one of several pre-defined DRC characteristics. The audio signal is encoded, and the DRC gain values are provided as metadata associated with the encoded audio signal. Several other embodiments are also described and claimed.