Audio Normalization Metadata for Device-Adaptive Dynamic Range
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Solution Overview
Problem
The varying dynamic range and loudness perception across different end user devices and audio programs lead to an inconsistent user experience during digital audio playback, as existing technologies lack a systematic approach to control audio quality using conventional encoding/decoding methods and metadata.
Innovation Solution
Applying an audio normalization gain value to produce a normalized signal, computing dynamic range control (DRC) gain values based on predefined characteristics, and embedding these values as metadata with the encoded signal to adjust the dynamic range during playback, allowing for real-time DRC adjustments based on user input, device context, and playback settings.
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 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-compress the audio signal, storing DRC gain values as metadata. This preliminary action prepares the signal for playback on devices with limited dynamic range, preventing clipping before it occurs during decoding.
Solution Approach 2:
The system dynamically adjusts DRC parameters based on the specific playback device's capabilities. The decoder reads device characteristics and selectively applies DRC gain values from metadata, enabling adaptive dynamic range control that optimizes loudness while preventing distortion for each device.
2Speed
If audio signals are encoded with data-rate reduction, then bandwidth consumption is reduced and transfer speed is improved, but audio quality may be degraded
Solution Approach 1:
The patent introduces DRC gain values as metadata as an intermediary element that carries additional audio control information without significantly increasing the encoded audio data rate. This intermediary structure enables quality enhancement at playback without compromising the efficiency of the original compression.
Solution Approach 2:
The audio data is segmented into the encoded audio signal and separate DRC gain value metadata. This segmentation allows independent optimization of compression for the audio signal while preserving quality control information in the metadata, enabling quality enhancement without increasing overall data rate significantly.
3Adaptability or versatility
If different end user devices are used for playback, then device compatibility and user choice are improved, but loudness perception varies significantly leading to inconsistent user experience
Solution Approach 1:
The patent changes the parameters of the audio signal by applying device-specific DRC gain values from metadata during decoding. This parameter adjustment compensates for variations in device acoustic characteristics, ensuring consistent loudness perception across different playback devices while maintaining broad device compatibility.
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.