Binaural Multi-Channel Decoding with HRTF Energy Correction

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Solution Overview

Problem

Existing methods for generating binaural signals from multi-channel audio face challenges in energy conservation and spectral coloring due to non-energy-conserving upmixing rules, especially when using HRTF filters, leading to artifacts in binaural output.

Innovation Solution

A multi-channel decoder is developed that calculates a gain factor to correct energy errors in the upmixing process, using upmix rule information and HRTF filter characteristics to produce an energy-corrected binaural signal without fully rendering the multi-channel signal, thereby reducing spectral coloring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If non-energy-conserving upmixing rules are used to achieve waveform matching, then time domain waveform matching is improved, but energy conservation deteriorates causing energy errors

Engineering Contradiction:

Improvewaveform matching accuracyVSAvoidenergy conservation

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent modifies the upmixing parameters by introducing energy correction factors that adjust the prediction coefficients. This allows the system to maintain waveform matching accuracy while compensating for energy losses introduced by non-energy-conserving upmixing rules, effectively changing the parameters to satisfy both waveform fidelity and energy conservation requirements

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If HRTF filters are combined linearly based on prediction parameters, then binaural signal generation is simplified, but spectral coloring artifacts increase

Engineering Contradiction:

Improvefilter combination complexityVSAvoidspectral coloring artifacts

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful spectral coloring artifacts into beneficial effects by using the prediction parameters that cause the artifacts to also guide the energy correction process. The same parameters that lead to waveform matching are now used to apply appropriate energy compensation, turning the source of artifacts into a mechanism for artifact reduction while maintaining computational simplicity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If prediction parameters are optimized for waveform matching, then time domain accuracy is improved, but frequency domain energy distribution deteriorates

Engineering Contradiction:

Improvetime domain waveform matchingVSAvoidfrequency domain energy distribution

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent segments the signal processing into distinct time domain and frequency domain components. Prediction parameters are optimized for time domain waveform matching while separate energy correction factors are applied to compensate for frequency domain energy distribution errors. This segmentation allows independent optimization of each domain without compromising the other

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS10412525B2Binaural multi-channel decoder in the context of non-energy-conserving upmix rules

Publication Date: 2019.09.10 DOLBY INTERNATIONAL AB

AI summary

A multi-channel decoder for generating a binaural signal from a downmix signal using upmix rule information on an energy-error introducing upmix rule for calculating a gain factor based on the upmix rule information and characteristics of head related transfer function based filters corresponding to upmix channels. The one or more gain factors are used by a filter processor for filtering the downmix signal so that an energy corrected binaural signal having a left binaural channel and a right binaural channel is obtained.