Spherical Quantization Dictionary for Efficient 3D Audio Direction Coding
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Solution Overview
Problem
Current methods for coding and decoding 3D directions of audio sources are resource-intensive and inefficient, particularly when dealing with high coding rates for DoA information.
Innovation Solution
A method for coding spatial directions of sound sources using a spherical quantization dictionary defined by elevation and azimuth coding, where the number of points per level is determined based on cumulative cardinality values, reducing computational complexity and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spherical quantization methods are used for coding spatial directions, then coding accuracy is maintained, but computational complexity and resource consumption increase significantly
Solution Approach 1:
The spherical quantization dictionary is segmented into multiple levels corresponding to different elevation ranges. Each level contains a specific number of azimuth points, creating a hierarchical structure that reduces the total number of points that need to be searched while maintaining coding accuracy. This segmentation allows the encoder to quickly identify the appropriate elevation level and then search only within that level's azimuth points.
Solution Approach 2:
Different regions of the sphere are assigned different numbers of quantization points based on their importance. The equatorial region (elevation 0) receives more points (Nθ(0)) while polar regions receive fewer points. This local quality adjustment optimizes the distribution of quantization resources, providing higher precision where needed and reducing complexity where less precision is required.
2Measurement precision
If high coding rates for DoA information are used, then spatial resolution is improved, but resource consumption and processing time increase
Solution Approach 1:
The quantization dictionary structure is designed to be dynamic in terms of point distribution. The number of azimuth points Nθ(i) varies dynamically with the elevation level i, allowing the system to adapt the precision to the actual spatial requirements at different elevation angles. This dynamic structure enables efficient coding by matching the quantization density to the spatial importance of each region.
Solution Approach 2:
The patent changes the parameter of point distribution from uniform to non-uniform based on elevation. By modifying how points are distributed across the sphere (concentrating more points at the equator and fewer at the poles), the system achieves better spatial resolution where it matters most while reducing the total computational burden.
3Adaptability or versatility
If a comprehensive spherical quantization dictionary is created to cover all possible directions, then coding completeness is achieved, but memory usage and initialization time increase
Solution Approach 1:
The comprehensive spherical dictionary is segmented into elevation levels, with each level containing only the necessary azimuth points for that specific elevation range. This segmentation avoids storing redundant points and allows the system to achieve coding completeness for all directions while using memory efficiently by only storing the minimum required points at each level.
Solution Approach 2:
Different elevation levels are assigned different densities of azimuth points based on local requirements. The equatorial level receives more points while polar levels receive fewer, optimizing memory usage while maintaining the ability to represent any direction on the sphere with sufficient accuracy.
Data Source
AI summary
A method for coding or decoding a spatial direction of a sound source, in which a spherical quantization dictionary is defined on a 3D sphere by coding elevation and azimuth, giving at least one coded elevation index (i) on a number of elevation levels (Nϕ) and a number of points per level (Nyθ(i)) determined on the basis of two successive cumulative cardinality values (cumN (i), cumN (i−1)), the cumulative cardinality value (cumN(i)) being representative of a number of points proportional to a total number of points and according to the area of a spherical region comprising at least one region delimited by the upper horizontal plane (ϕ=(i+½)δϕ) of the positive elevation level of the coded elevation index (i) and a lower horizontal plane of the sphere.