Presentation Loudness Metadata for Consistent Audio Decoding
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Solution Overview
Problem
Existing audio encoding and decoding technologies struggle to maintain accurate loudness consistency across different content substreams and presentations, leading to potential inaccuracies that exceed industry tolerances, such as 0.1 dB, which is crucial for maintaining consistent audio levels across various audio content configurations.
Innovation Solution
The proposed solution involves providing loudness data for each presentation, using mixing coefficients and dynamic range compression (DRC) data within the encoding process, allowing decoders to accurately control playback gain and ensure consistent loudness levels by combining substreams based on psychoacoustic modeling, even when user preferences or content changes occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If loudness data is provided for each content substream individually, then the decoder can process each substream separately, but the overall loudness accuracy deteriorates because adding individual loudness values does not equal the loudness of the combined signal
Solution Approach 1:
The patent segments the loudness information by providing separate loudness data for each content substream (dialog, music, effects) while also providing an overall presentation loudness value. This allows the decoder to selectively process substreams based on user preferences while maintaining accurate overall loudness control through the presentation-level loudness data.
Solution Approach 2:
The patent introduces an intermediary approach by providing both individual substream loudness data and overall presentation loudness data. The decoder uses the overall presentation loudness as a reference to maintain accurate loudness levels when combining substreams, while individual substream data allows for flexible mixing and selection without compromising overall loudness accuracy.
2Adaptability or versatility
If multiple content substreams are mixed to create different presentations, then content flexibility and adaptability improve, but maintaining consistent loudness across all presentations becomes more difficult
Solution Approach 1:
The patent applies universality by providing a standardized loudness data structure that works across all presentations and substream combinations. Each presentation contains loudness data for its constituent substreams plus an overall presentation loudness value, allowing the same decoding approach to maintain loudness consistency regardless of which substreams are active or how they are mixed.
Solution Approach 2:
The patent implements feedback by providing measured loudness values for each presentation configuration in the broadcast signal. The decoder uses these feedback loudness values to adjust its mixing and gain control, ensuring that regardless of which substreams are combined or how mixing coefficients are applied, the output loudness remains consistent with the reference level.
3Ease of operation
If loudness control is implemented at the decoder, then user flexibility improves, but the complexity of the decoding process increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding loudness data for each content substream and each presentation configuration in the broadcast signal before transmission. This allows the decoder to simply retrieve and apply these pre-computed values rather than performing complex loudness measurements and calculations in real-time, reducing decoder complexity while maintaining user flexibility.
Solution Approach 2:
The patent implements self-service by providing the decoder with all necessary loudness information (individual substream loudness values and overall presentation loudness values) needed to perform accurate loudness control independently. The decoder uses this self-provided information to automatically adjust mixing coefficients and gain levels without requiring external calibration or complex processing algorithms.
Data Source
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AI summary
This disclosure falls into the field of audio coding, in particular it is related to the field of providing a framework for providing loudness consistency among differing audio output signals. In particular, the disclosure relates to methods, computer program products and apparatus for encoding and decoding of audio data bitstreams in order to attain a desired loudness level of an output audio signal.