Loudness Metadata Processing for Consistent Volume and Sound Quality
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Solution Overview
Problem
The challenge lies in efficiently normalizing the loudness level of audio content across different sources and genres, as existing methods fail to maintain consistent volume levels, leading to user inconvenience due to varying loudness standards and the 'Loudness War' phenomenon, where content creators prioritize loudness over quality, resulting in inconsistent playback experiences.
Innovation Solution
An audio signal processing method and apparatus that utilize loudness metadata, specifically the Quality Secure Histogram Index (QSHI), to adjust and normalize the output loudness level by measuring and predicting loudness parameters, ensuring cognitive sound quality is maintained without compromising sound quality, and applying a loudness limiter to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If loudness normalization is applied to maintain consistent volume levels, then user convenience is improved, but the complexity of the audio processing system increases due to multiple processing steps
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing loudness metadata (including QSHI values) during audio content encoding. This allows the playback device to directly use pre-computed loudness information without performing complex real-time analysis, thereby reducing processing complexity while maintaining normalization functionality.
Solution Approach 2:
The patent introduces loudness metadata as an intermediary element that carries pre-analyzed loudness characteristics between the encoding and playback stages. This metadata acts as a mediator that simplifies the interaction between different processing components, enabling efficient loudness normalization without requiring complex real-time analysis.
2Stability of the object's composition
If loudness normalization processing is applied to audio content, then consistent volume levels are achieved, but sound quality may deteriorate due to excessive processing
Solution Approach 1:
The patent applies local quality by using the QSHI (Quality Secure Histogram Index) parameter to identify specific portions of audio content where loudness processing should be applied or limited. This allows differential processing where sound quality is preserved in critical regions while still achieving volume normalization overall, preventing uniform aggressive processing that would degrade quality.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting processing strength based on the QSHI parameter and loudness histogram analysis. The system modifies processing parameters adaptively according to the specific characteristics of each audio segment, ensuring normalization is achieved without excessive processing that would compromise sound quality.
3Reliability
If multiple loudness processing steps are applied to ensure quality, then sound quality protection is improved, but the processing time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-computing loudness histograms and QSHI values during the encoding phase. This shifts the computational burden to the encoding stage, allowing fast playback with minimal real-time processing while maintaining reliable sound quality protection through pre-analyzed parameters.
Solution Approach 2:
The patent extracts essential loudness characteristics (QSHI, loudness histogram) from the audio content and stores them as metadata. This extraction separates the complex analysis function from the playback function, enabling fast processing during playback while maintaining quality protection through the use of pre-extracted parameters.
Data Source
AI summary
An audio signal processing device comprises: a receiver for receiving an input audio signal; a processor for generating loudness metadata corresponding to the input audio signal; and an outputter for transmitting the loudness metadata generated by the processor. The processor is configured to acquire loudness information analyzed from input content, acquires loudness information about the input audio signal by measuring the loudness of the input audio signal, generates the loudness metadata by converting the loudness information, and transmits, through the outputter, the generated loudness metadata to an output device for outputting the input audio signal.