Ambisonics Signal Rendering via Segmented Pre-Rendering and NFC Filtering

Solution Overview

Problem

The technical problem addressed in this patent is the inefficient rendering of ambisonics audio signals, particularly in adapting the rendering to different speaker arrangements.

Innovation Solution

The solution involves a method for rendering ambisonics signals using a loudspeaker arrangement with S loudspeakers, which includes converting ambisonics channel signals into unfiltered pre-rendered signals and performing near field compensation (NFC) filtering to generate filtered loudspeaker channel signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the number of audio channels and directivity patterns is increased to improve soundfield description precision, then the precision of soundfield description is improved, but the computational complexity and rendering efficiency deteriorate

Engineering Contradiction:

Improvesoundfield description precisionVSAvoidrendering complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the rendering process into two distinct stages: pre-rendering (converting ambisonics channels to unfiltered pre-rendered signals) and NFC filtering (applying near-field compensation). This segmentation allows the computationally intensive conversion to be performed once during pre-rendering, while the NFC filtering stage processes fewer signals, thereby reducing overall computational complexity while maintaining high soundfield description precision through higher-order ambisonics channels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs the conversion from ambisonics channel signals to pre-rendered signals in advance during a pre-rendering stage. This preliminary action separates the heavy computational workload from the real-time rendering stage, allowing the main rendering process to operate more efficiently with reduced computational burden while preserving the high precision benefits of multiple ambisonics channels and directivity patterns.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the ambisonics signal is converted directly to loudspeaker signals without pre-rendering, then the rendering process is simpler, but the computational complexity during rendering increases

Engineering Contradiction:

Improverendering process simplicityVSAvoidrendering efficiency

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent performs the conversion from ambisonics channel signals to pre-rendered signals in advance during a pre-rendering stage. This preliminary action separates the heavy computational workload from the real-time rendering stage, allowing the main rendering process to operate more efficiently with reduced computational burden while preserving the high precision benefits of multiple ambisonics channels and directivity patterns.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the rendering process into two distinct stages: pre-rendering (converting ambisonics channels to unfiltered pre-rendered signals) and NFC filtering (applying near-field compensation). This segmentation allows the computationally intensive conversion to be performed once during pre-rendering, while the NFC filtering stage processes fewer signals, thereby reducing overall computational complexity while maintaining high soundfield description precision through higher-order ambisonics channels.

Inventive Principle:

Principle #1Segmentation

3Measurement precision

If NFC filtering is applied to all ambisonics channel signals before conversion, then the near-field compensation is more accurate, but the computational complexity increases

Engineering Contradiction:

Improvenear-field compensation accuracyVSAvoidfiltering complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the rendering process into two distinct stages: pre-rendering (converting ambisonics channels to unfiltered pre-rendered signals) and NFC filtering (applying near-field compensation). This segmentation allows the computationally intensive conversion to be performed once during pre-rendering, while the NFC filtering stage processes fewer signals, thereby reducing overall computational complexity while maintaining high soundfield description precision through higher-order ambisonics channels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies NFC filtering selectively to M unfiltered pre-rendered signals rather than to all N ambisonics channel signals. This partial action approach reduces the number of filtering operations required while still achieving effective near-field compensation for the rendered output, thereby balancing compensation accuracy with computational efficiency.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20250142276A1Methods and devices for rendering an ambisonics audio signal

Publication Date: 2025.05.01 DOLBY LABORATORIES LICENSING CORP

AI summary

The present document describes a method (400) for rendering an ambisonics signal using a loudspeaker arrangement comprising S loudspeakers. The method (400) comprises converting (401) a set of N ambisonics channel signals (111) into a set of unfiltered pre-rendered signals (211), with N>1 and S>1. Furthermore, the method (400) comprises performing (402) near field compensation, referred to as NFC, filtering of M unfiltered pre-rendered signals (211) of the set of unfiltered pre-rendered signals (211) to provide a set of S filtered loudspeaker channel signals (114) for rendering using the corresponding S loudspeakers.