Binaural Multi-Channel Decoding With HRTF Gain 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 the use of predictive upmix rules, especially when downmixing signals with uncorrelated channels of comparable magnitudes, leading to energy errors and artifacts in the binaural output.
Innovation Solution
A multi-channel decoder is developed that calculates a gain factor to correct energy errors by using upmix rule information and HRTF filter characteristics, allowing for energy-corrected binaural signal generation without fully rendering the multi-channel signal, thereby reducing spectral coloring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If predictive upmix 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 applies preliminary action by pre-calculating gain factors based on HRTF filter characteristics and upmix rule information before actual binaural signal generation. This allows the system to compensate for energy errors in advance during the upmixing process, rather than dealing with them after binaural rendering has occurred
Solution Approach 2:
The patent changes parameters by introducing gain factors that modify the energy distribution in the upmixed channels. These gain factors are derived from HRTF filter characteristics and are applied to adjust the energy balance, transforming the energy-error-prone upmix process into an energy-corrected one
2Device complexity
If predictive upmix rules are used to generate binaural signals, then the binaural signal can be obtained without fully rendering the multi-channel signal, but spectral coloring artifacts occur especially when channels are uncorrelated with comparable magnitudes
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating and applying gain factors that counteract the spectral coloring artifacts before they fully manifest in the binaural output. The gain factors are derived from HRTF characteristics and are designed to compensate for the harmful effects of predictive upmixing on uncorrelated channels
Solution Approach 2:
The patent introduces gain factors as an intermediary element between the upmix rule information and the final binaural signal. These gain factors act as a mediator that adjusts the energy distribution to prevent spectral coloring, bridging the gap between computational efficiency and audio quality
3Reliability
If linear combination of HRTF filters is performed based on transmitted spatial prediction parameters, then binaural decoding is achieved, but energy distribution is not preserved and artifacts are amplified
Solution Approach 1:
The patent applies feedback by using HRTF filter characteristics as feedback information to adjust the gain factors. The system continuously refines the energy distribution by comparing the predicted upmix results with the actual HRTF filter responses, creating a closed-loop system that preserves energy distribution
Solution Approach 2:
The patent changes parameters by deriving gain factors from HRTF filter characteristics and applying these parameters to correct the energy distribution. This transforms the fixed linear combination approach into a dynamic parameter-adjusted system that preserves energy while maintaining binaural decoding accuracy
Data Source
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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 (180) 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 (182) for filtering the downmix signal so that an energy corrected binaural signal having a left binaural channel and a right binaural channel is obtained.