Audio Dynamic Range Control Using Multi-Band Compression Stages
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Solution Overview
Problem
Conventional audio processing systems in mobile devices face challenges in handling a wide range of audio signals with varying qualities, requiring flexible processing capabilities to manage duplex operations efficiently, especially with the integration of new voice and audio compression techniques in wireless systems.
Innovation Solution
A method and system for dynamic range control that involves expanding the dynamic range of audio signals using a dynamic expander, dividing them into frequency bands for individual compression, and utilizing a full-band compressor, along with adaptive thresholds and envelope detection, to optimize audio quality and loudness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If audio signals are processed with fixed gain and filtering in conventional codecs, then the system structure is simple, but the system cannot adapt to different audio qualities and sources
Solution Approach 1:
The patent implements dynamic range control by dividing the audio signal into multiple frequency bands and applying different compression/expansion operations to each band based on real-time signal characteristics. This dynamic processing allows the system to adapt to varying audio qualities and sources while maintaining manageable complexity through modular band-processing architecture.
Solution Approach 2:
The audio signal is segmented into multiple frequency bands, with each band processed independently through its own compression and expansion operations. This segmentation enables targeted processing of different frequency ranges according to their specific characteristics, improving overall adaptability without requiring complete redesign of the entire processing chain.
2Reliability
If the audio signal is compressed to reduce distortion, then the audio quality improves, but the dynamic range is reduced
Solution Approach 1:
Different compression and expansion operations are applied to different frequency bands based on their local characteristics. This allows the system to reduce distortion in specific bands where it is most problematic while preserving the dynamic range in bands where it is less critical, thereby improving audio quality without uniformly sacrificing dynamic range across the entire signal.
Solution Approach 2:
The system employs dynamic compression and expansion operations that adjust their parameters based on the instantaneous characteristics of each frequency band. This dynamic approach allows the system to reduce distortion when and where it occurs while maintaining dynamic range during portions of the signal where distortion is less problematic, resolving the contradiction between quality improvement and dynamic range preservation.
3Adaptability or versatility
If multiple audio sources are processed simultaneously in duplex operations, then the system functionality is enhanced, but the processing requirements and complexity increase
Solution Approach 1:
The duplex audio processing system divides incoming and outgoing audio signals into multiple frequency bands, allowing independent processing of each band. This segmentation enables the system to handle multiple audio sources simultaneously with reduced computational burden compared to processing the entire spectrum as a single unit, as each band can be processed in parallel with simpler operations.
Solution Approach 2:
The patent implements a universal processing architecture where the same compression, expansion, and filtering operations are applied across multiple frequency bands and both uplink and downlink directions. This multi-functional approach allows the system to handle diverse audio sources and duplex operations using a standardized processing framework, enhancing versatility without proportionally increasing complexity.
Data Source
AI summary
Methods and systems for dynamic range control in an audio processing system are disclosed and may include controlling a dynamic range of an audio signal by expanding the dynamic range utilizing a dynamic expander, and dividing the audio signal into a plurality of frequency bands. Each of the bands may be individually compressed utilizing a multi-band compressor. A sum of the individually compressed frequency bands may be compressed utilizing a full-band compressor. The audio signal may be filtered utilizing a pre-emphasis filter, such as an infinite impulse response filter and may be divided into frequency bands utilizing one or more finite impulse response filters and/or delay modules. The dynamic expander may include adaptive thresholds and an envelope detector. Each of the frequency bands may be compressed utilizing syllabic compression in the multi-band compressor. The compressed sum of compressed plurality of bands may be processed utilizing an audio CODEC.