Audio Loudness Metadata Conversion for Consistent Media Playback
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Solution Overview
Problem
Existing multimedia playback systems struggle with inconsistent audio leveling due to varying listening environments, diverse audio formats, and computational complexity, particularly in portable devices, without altering the original audio content.
Innovation Solution
Implementing encoder-generated metadata with reversible relationships between different loudness measurement algorithms (like ITU-R BS.1770 and Replay Gain) to normalize audio levels, ensuring consistent playback across diverse content and environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If loudness measurements are performed separately for each playback mode (e.g., headphones, loudspeaker, TV speaker), then the loudness control is accurate for each specific mode, but the metadata size increases and requires multiple separate measurements
Solution Approach 1:
The patent creates a reference loudness measurement in a first playback mode and uses a transfer function to generate loudness measurements for second and third playback modes. This copying approach allows one actual measurement to serve multiple playback modes, reducing the quantity of metadata while maintaining measurement accuracy through mathematical transformation.
Solution Approach 2:
The patent transforms loudness measurement parameters between different playback modes using transfer functions. By changing the parameters (loudness values) based on the relationship between playback modes, the system can derive accurate measurements for headphone and loudspeaker modes from a single TV speaker mode measurement, reducing metadata requirements while preserving precision.
2Measurement precision
If loudness measurements are performed separately for each playback mode, then the loudness control is accurate for each specific mode, but the system complexity increases due to multiple separate measurements and metadata
Solution Approach 1:
The patent implements a universal loudness measurement approach where a single reference measurement in TV speaker mode serves multiple playback modes through transfer functions. This multi-functionality allows the same measurement infrastructure to support headphones, loudspeaker, and TV speaker modes without requiring separate measurement systems for each mode, thereby reducing system complexity while maintaining accuracy.
Solution Approach 2:
The patent introduces transfer functions as intermediaries that bridge different playback modes. These transfer functions act as mathematical mediators that translate the reference loudness measurement into accurate predictions for other playback modes, eliminating the need for direct measurements in each mode and simplifying the overall system architecture.
3Device complexity
If loudness measurements are performed in a reference playback mode (e.g., TV speaker) and converted to other modes using transfer functions, then the metadata size and system complexity are reduced, but measurement accuracy may be compromised for the converted modes
Solution Approach 1:
The patent performs preliminary calibration by measuring the transfer functions between different playback modes in advance. These pre-determined transfer functions are stored and applied during normal operation, allowing accurate conversion of loudness measurements without real-time complexity. The preliminary action of characterizing the relationship between modes ensures precision is maintained when converting measurements.
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.