Binaural Decoder Gain Correction for Non-Conserving Upmix Rules
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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 downmixed signals and spatial parameters.
Innovation Solution
A multi-channel decoder that calculates a gain factor to reduce or eliminate 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, and applying this gain factor during filtering to mitigate spectral coloring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-energy-conserving upmixing rules are used to generate binaural signals from downmixed signals, then computational efficiency is improved and audio quality is enhanced, but energy errors and spectral coloring artifacts occur
Solution Approach 1:
The patent applies parameter changes by introducing gain factors that modify the energy characteristics of the upmixed signal. These gain factors are calculated based on the upmixing rule and HRTF filter characteristics to compensate for energy losses introduced by non-energy-conserving upmixing, thereby resolving the contradiction between computational efficiency and energy conservation
Solution Approach 2:
The patent uses gain factors as intermediary elements that mediate between the downmixed signal and the final binaural output. These gain factors act as compensatory mechanisms that correct energy errors without requiring full re-rendering of the multi-channel signal, thus maintaining computational efficiency while reducing energy loss
2Speed
If non-energy-conserving upmixing rules are used to generate binaural signals, then processing speed is improved, but spectral coloring artifacts are introduced
Solution Approach 1:
The patent modifies spectral parameters by applying gain factors that are specifically calculated to counteract spectral coloring effects. These gain factors adjust the frequency response of the upmixed signal based on the interdependence between upmixing rules and HRTF filters, thereby eliminating spectral artifacts while maintaining fast processing
Solution Approach 2:
The patent implements a feedback mechanism where the gain factors are calculated based on the characteristics of the upmixing rule and HRTF filters. This feedback loop allows the system to automatically compensate for spectral coloring artifacts introduced by non-energy-conserving upmixing, resolving the contradiction between processing speed and audio quality
3Device complexity
If HRTF filters are combined using non-energy-conserving upmixing, then device complexity is reduced, but energy distribution accuracy deteriorates
Solution Approach 1:
The patent changes the energy parameters of the combined HRTF filters by applying gain factors that are calculated to preserve energy distribution accuracy. This allows the system to use simplified non-energy-conserving upmixing rules while still achieving accurate energy distribution through the compensatory gain adjustment
Solution Approach 2:
The gain factors serve as intermediary elements that bridge the gap between simple non-energy-conserving upmixing and accurate energy distribution. By introducing these compensatory factors, the system achieves both low device complexity and high energy distribution accuracy
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.