Spherical Harmonic Coefficient Compression via Energy Analysis

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Solution Overview

Problem

Current audio coding technologies face challenges in efficiently compressing multi-channel audio data, particularly with higher-order spherical harmonic coefficients, which are essential for representing three-dimensional soundfields, while maintaining backward compatibility and adaptability to various speaker geometries.

Innovation Solution

The method involves performing an energy analysis on spherical harmonic coefficients to determine a reduced version, dynamically applying thresholds based on energy volumes, and generating a bitstream, which adapts to the significance of each coefficient, thereby reducing data while ensuring quality and compatibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If higher-order spherical harmonic coefficients are used to represent three-dimensional soundfields, then the accuracy and quality of spatial audio representation is improved, but the data size and processing complexity increase

Engineering Contradiction:
Improvespatial audio representation accuracyVSAvoiddata size
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent extracts only the salient spherical harmonic coefficients that contribute significantly to spatial audio quality. By performing energy analysis and comparing coefficient magnitudes against thresholds, the system identifies and retains only those coefficients above the threshold, discarding redundant information while preserving perceptual quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent dynamically adjusts the energy threshold parameter based on the characteristics of the audio signal and speaker configuration. By changing the threshold parameter adaptively, the system optimizes the balance between retaining sufficient spatial information and reducing data size, allowing flexible compression ratios while maintaining quality.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If higher-order spherical harmonic coefficients are used to represent three-dimensional soundfields, then the accuracy and quality of spatial audio representation is improved, but the processing complexity increases

Engineering Contradiction:
Improvespatial audio representation accuracyVSAvoidprocessing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the salient spherical harmonic coefficients that contribute significantly to spatial audio quality. By performing energy analysis and comparing coefficient magnitudes against thresholds, the system identifies and retains only those coefficients above the threshold, discarding redundant information while preserving perceptual quality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by processing only the necessary subset of coefficients rather than all higher-order coefficients. By selectively analyzing and retaining only those coefficients that exceed the energy threshold, the system reduces computational load while maintaining sufficient spatial representation accuracy.

Inventive Principle:
Principle #16Partial or excessive action

3Quantity of substance

If spherical harmonic coefficients are compressed by eliminating non-salient coefficients, then the data size is reduced, but the perceived sound quality may be impacted

Engineering Contradiction:
Improvedata sizeVSAvoidperceived sound quality
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The patent dynamically adjusts the energy threshold parameter based on the characteristics of the audio signal and speaker configuration. By changing the threshold parameter adaptively, the system optimizes the balance between retaining sufficient spatial information and reducing data size, allowing flexible compression ratios while maintaining quality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses energy analysis feedback to identify which coefficients contribute significantly to the soundfield representation. By continuously analyzing the energy distribution across coefficients and adjusting retention decisions based on this feedback, the system ensures that only non-impactful coefficients are removed, preserving perceived quality.

Inventive Principle:
Principle #23Feedback

4Productivity

If spherical harmonic coefficients are compressed to reduce data size, then the storage and transmission efficiency is improved, but the adaptability to various speaker geometries may be reduced

Engineering Contradiction:
Improvecompression efficiencyVSAvoidspeaker geometry adaptability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent dynamically adjusts the energy threshold parameter based on the characteristics of the audio signal and speaker configuration. By changing the threshold parameter adaptively, the system optimizes the balance between retaining sufficient spatial information and reducing data size, allowing flexible compression ratios while maintaining quality.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9466302B2Coding of spherical harmonic coefficients
Publication Date: 2016.10.11 QUALCOMM INC
  • US9466302B2 patent drawing
  • US9466302B2 patent drawing
  • US9466302B2 patent drawing

AI summary

In general, techniques are described for coding of spherical harmonic coefficients representative of a three dimensional soundfield. A device comprising a memory and one or more processors may be configured to perform the techniques. The memory may be configured to store a plurality of spherical harmonic coefficients. The one or more processors may be configured to perform an energy analysis with respect to the plurality of spherical harmonic coefficients to determine a reduced version of the plurality of spherical harmonic coefficients.