Binaural Decoder Gain Compensation for HRTF Energy Errors
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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 with downmix signals containing spatial parameters that are not energy-aware.
Innovation Solution
A multi-channel decoder is developed that calculates a gain factor to correct energy errors in binaural signal generation by using upmix rule information and HRTF filter characteristics, allowing for energy-corrected binaural signal production without fully rendering the multichannel signal, thereby reducing spectral coloring artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-energy-conserving upmixing rules are used to generate binaural signals from downmix signals, then computational efficiency is improved and audio quality is enhanced, but energy errors occur and spectral coloring artifacts are introduced
Solution Approach 1:
The patent calculates compensation gain factors before applying HRTF filters to the downmix signals. By pre-computing the gain factors based on upmix rule information and HRTF filter characteristics, the system compensates for energy errors in advance, preventing spectral coloring artifacts while maintaining computational efficiency of the shortcut binaural rendering approach
Solution Approach 2:
The patent introduces gain factor parameters that are calculated based on the relationship between upmix rule information and HRTF filter characteristics. These parameter adjustments compensate for energy losses introduced by non-energy-conserving upmixing, allowing the system to maintain both computational efficiency and energy accuracy
2Measurement precision
If prediction parameters are used for waveform matching in upmixing, then time domain accuracy is improved, but energy distribution accuracy deteriorates due to automatic energy loss
Solution Approach 1:
The patent uses upmix rule information as feedback to calculate compensation gain factors. This feedback mechanism allows the system to adjust the energy distribution after waveform matching has been performed, correcting the energy losses introduced by prediction-based upmixing while preserving the waveform matching accuracy
Solution Approach 2:
The patent modifies the energy distribution parameters by applying calculated gain factors to the downmix signals after prediction-based upmixing. This parameter adjustment restores energy distribution accuracy while maintaining the benefits of waveform matching achieved through prediction parameters
3Device complexity
If HRTF filters are linearly combined based on prediction parameters, then binaural signal generation is simplified, but spectral coloring artifacts increase when prediction performance is poor
Solution Approach 1:
The patent calculates compensation gain factors before combining HRTF filters, based on upmix rule information and filter characteristics. This preliminary compensation prevents spectral coloring artifacts from occurring when prediction performance is poor, while maintaining the simplicity of linear filter combination
Solution Approach 2:
The patent applies different compensation gain factors to different HRTF filter combinations based on their specific characteristics and the upmix rule information. This asymmetric approach targets the specific sources of spectral coloring artifacts without increasing overall system complexity
Data Source
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.