Binaural Gain Control Integrated With Spatial Audio Rendering
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Solution Overview
Problem
Conventional automatic gain control (AGC) and dynamic range compression algorithms introduce delays in audio systems, which are undesirable in head-tracking spatial audio applications, leading to suboptimal audio quality and increased headroom requirements due to varying audio signal levels and orientations.
Innovation Solution
A processor-based system that estimates audio signal levels and applies gain control based on the position and orientation of sound sources relative to a listener, integrating gain control into the spatial audio processing system without introducing additional delay, using metadata and head-tracking information to synthesize binaural output channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional automatic gain control (AGC) and dynamic range compression algorithms are used to balance audio signal levels, then audio signal level balance is improved, but time delay is introduced which deteriorates spatial audio quality
Solution Approach 1:
The patent merges the gain control function with the spatial audio rendering process by integrating level estimation and gain calculation into the existing binaural synthesis pipeline. The processor estimates audio levels and calculates gain values within the same processing stage that generates the binaural output, eliminating the need for separate AGC processing stages that would introduce additional delay.
Solution Approach 2:
The system performs preliminary level estimation and gain calculation based on predicted head positions and sound source directions before the actual audio rendering occurs. By pre-calculating the required gain values using the estimated positions and directional information, the system prepares the gain control parameters in advance, allowing immediate application without processing delay when the audio is rendered.
2Ease of operation
If gain control is applied separately from spatial audio processing, then gain control function is achieved, but system complexity and processing delay increase
Solution Approach 1:
The patent combines multiple functions including level estimation, gain calculation, and spatial audio rendering into a single integrated processing pipeline. The processor performs level estimation of the audio signal, calculates gain values based on estimated positions, and synthesizes the binaural output all in one coherent process, eliminating the need for separate gain control modules and reducing overall system complexity.
Solution Approach 2:
The spatial audio processor is designed to perform multiple functions simultaneously: it estimates audio levels, determines sound source directions, predicts head positions, calculates gain values, and generates binaural output. This multi-functional approach allows the same processing infrastructure to handle both spatial rendering and gain control without requiring additional dedicated hardware or software components.
3Reliability
If additional headroom is allocated for orientation variability in binaural audio signals, then clipping is avoided, but audio quality and listening experience deteriorate
Solution Approach 1:
The system performs preliminary estimation of the audio signal level and the maximum expected gain variation based on the sound source direction and predicted head orientation. By calculating the required headroom in advance and applying appropriate pre-gain or limiting, the system ensures that the final binaural output will not clip regardless of head movement, while minimizing the headroom allocation to preserve audio quality.
Solution Approach 2:
The patent implements dynamic headroom management by continuously adjusting the gain values based on the estimated head position and sound source direction. Rather than allocating fixed excessive headroom, the system dynamically calculates the minimum required headroom for each audio frame based on the current spatial configuration, applying gain control that adapts to the listener's head movements while maintaining optimal audio quality.
Data Source
AI summary
Apparatus including a processor configured to: provide a position for at least one sound source relative to a reference position; analyse at least one input audio signal associated with the at least one sound source to determine at least one gain value based on the at least one input audio signal and the position for the at least one sound source relative to the reference position; and synthesize at least two output channels based on the at least one input audio signal, a directional transfer function pair, the at least one gain value and the position for the at least one sound source relative to the reference position.