Real-Time Loudness Range Processing for Live Audio Compliance
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Solution Overview
Problem
Existing audio signal processors lack the ability to automatically control loudness level and range in real-time without prior analysis or metadata, making it difficult to comply with regulations requiring specific loudness standards in live broadcasts and other applications.
Innovation Solution
A loudness signal processor that determines a time-varying gain based on a time-varying level distribution and predetermined target loudness parameters, using continuous non-parametric statistical signal analysis to control loudness level and range in real-time, allowing for dynamic compression, expansion, or gain alignment without pre-analysis or metadata.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If real-time processing is implemented without pre-analysis or metadata, then processing speed and latency are improved, but the ability to accurately control loudness level and range deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the processor continuously monitors the input signal's loudness level and range, compares these measurements against target values, and dynamically adjusts the gain in real-time. This closed-loop control enables accurate loudness normalization without requiring pre-analysis or metadata, resolving the contradiction between real-time processing speed and measurement precision.
Solution Approach 2:
The processor performs self-service by automatically analyzing the statistical properties of the input signal and determining appropriate gain values without external control signals or pre-provided metadata. The system independently measures loudness level and range, generates transfer functions based on these measurements, and applies corrective gain, enabling real-time operation while maintaining accurate loudness control.
2Device complexity
If traditional dynamic range compressors are used with fixed parameters, then device complexity is reduced, but adaptability to different audio content deteriorates
Solution Approach 1:
The patent transforms the static, fixed-parameter compressor into a dynamic system where the transfer function adapts in real-time based on the statistical properties of the input signal. The processor continuously updates the gain values according to the measured loudness level and range, enabling the same device to optimally process diverse audio content without requiring multiple pre-configured settings or increasing structural complexity.
Solution Approach 2:
The system achieves adaptability by dynamically changing the gain parameters based on real-time statistical analysis of the input signal. Instead of using fixed compression ratios and thresholds, the processor adjusts these parameters continuously according to the measured loudness characteristics, allowing a single device with moderate complexity to adapt to various audio content types.
3Measurement precision
If 2-pass processing with pre-analysis is implemented, then loudness control accuracy is improved, but processing time and productivity are reduced
Solution Approach 1:
The patent eliminates the interruption caused by 2-pass processing by implementing continuous real-time analysis and control. The processor performs loudness measurement, transfer function generation, and gain application simultaneously and continuously as the signal passes through, maintaining both measurement accuracy and processing throughput without requiring separate analysis and processing passes.
Solution Approach 2:
The processor performs preliminary estimation of the transfer function based on initial statistical measurements, then continuously refines this estimate as more data becomes available. This allows the system to begin processing immediately with preliminary gain values while improving accuracy over time, avoiding the need to wait for complete pre-analysis before starting processing.
Data Source
AI summary
Loudness signal processors and methods for processing an input audio signal in order to control a resulting integrated loudness level and a resulting loudness range of an output audio signal by a predetermined target loudness level and by a predetermined target loudness range, the processors and methods comprising level detection and level distribution analysis; transfer function generation based on the level distribution, the predetermined target loudness level and the predetermined target loudness range; and calculation of a gain to apply to said input audio signal, resulting in said output audio signal.