Directional Audio Parameter Coding With Adaptive Spatial Quantization
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Solution Overview
Problem
Current methods for encoding directional audio coding parameters, such as DirAC metadata, face challenges in achieving low bit-rates while maintaining high quality, particularly due to the large amount of data required for transmitting 3D audio scenes, and previous solutions have compromised on spatial resolution or limited applications to specific scenarios like teleconferences.
Innovation Solution
The proposed solution involves quantizing and encoding directional audio coding parameters with different resolutions for diffuseness and direction parameters, using a parameter quantizer and encoder to generate an encoded representation, and employing different encoding modes based on diffuseness values to optimize bit-rate reduction while preserving quality, including quasi-uniform coverage of the 3D sphere and extended Golomb-Rice coding for efficient entropy coding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If directional audio coding parameters are transmitted with high spatial resolution, then audio quality is improved, but data transmission volume increases
Solution Approach 1:
The patent segments the audio scene into multiple frequency bands and applies different quantization resolutions to different parameter types (diffuseness vs. direction). This segmentation allows high spatial resolution to be maintained where perceptually important while reducing data volume in less critical areas, directly resolving the contradiction between audio quality and transmission volume.
Solution Approach 2:
The patent implements local quality by applying different quantization precision levels to different parameters based on their perceptual importance. Diffuseness parameters use coarser quantization while direction parameters use finer quantization, particularly in frequency bands where directional information is more critical. This localized differentiation maintains audio quality where needed while reducing overall data transmission volume.
2Ease of manufacture
If uniform quantization resolution is applied to all parameters, then encoding simplicity is maintained, but encoding efficiency decreases
Solution Approach 1:
The patent introduces dynamic, adaptive quantization where the resolution and coding mode for each parameter are adjusted based on local signal characteristics such as diffuseness values and frequency band properties. This dynamic adaptation improves encoding efficiency by allocating bits according to perceptual importance while maintaining reasonable encoding complexity through systematic decision rules.
Solution Approach 2:
The patent changes parameters adaptively by selecting different quantization resolutions and coding modes (e.g., Golomb-Rice coding with different parameters) based on the statistical properties of the audio signal in each frequency band. This parameter adaptation optimizes the trade-off between encoding simplicity and efficiency by automatically adjusting to signal characteristics.
3Measurement precision
If high bit-rate coding is used, then audio quality is maintained, but transmission cost increases
Solution Approach 1:
The patent applies partial action by using high precision coding only where necessary (low diffuseness regions where directional information is critical) and coarser coding where it suffices (high diffuseness regions where directional precision is less important). This selective application of high bit-rate coding maintains audio quality in critical areas while reducing overall transmission cost.
Solution Approach 2:
The patent changes the coding parameters (quantization resolution, coding mode) based on the diffuseness parameter and frequency band, transitioning between different bit-rate regimes adaptively. This dynamic parameter adjustment maintains high audio quality where needed while reducing bit-rate to lower transmission costs in less critical regions.
Data Source
AI summary
An apparatus for encoding directional audio coding parameters comprising diffuseness parameters and direction parameters having a parameter calculator (100) for calculating the diffuseness parameters with a first time or frequency resolution and for calculating the direction parameters with a second time or frequency resolution; and a quantizer and encoder processor (200) for generating a quantized and encoded representation of the diffuseness parameters and the direction parameters.