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 with downmixed signals and spatial parameters.
Innovation Solution
A multi-channel decoder that calculates a gain factor to correct energy errors in binaural signal generation by utilizing upmix rule information and HRTF filter characteristics, allowing for energy-corrected binaural signal production without fully rendering multichannel signals, thereby reducing spectral coloring artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-energy-conserving upmixing rules are used for binaural signal generation, then computational efficiency is improved, but energy errors and spectral coloring artifacts occur
Solution Approach 1:
The patent segments the binaural signal generation process into two independent parts: (1) spatial parameter calculation from downmixed signals using efficient upmixing rules, and (2) HRTF filtering applied separately to reconstruct accurate binaural signals. This segmentation allows computational efficiency in parameter extraction while maintaining energy conservation in the final signal reconstruction.
Solution Approach 2:
The patent introduces spatial parameters (inter-channel coherence, channel level difference) as intermediary elements that bridge the downmixed signals and the final binaural output. These intermediaries carry essential spatial information without requiring full multichannel signal reconstruction, thus improving computational efficiency while preserving energy characteristics through proper HRTF filtering.
2Device complexity
If non-energy-conserving upmixing rules are used, then device complexity is reduced, but spectral coloring artifacts increase
Solution Approach 1:
The decoder complexity is reduced by segmenting the processing into spatial parameter extraction from downmixed signals and separate HRTF filtering, avoiding full multichannel signal reconstruction. This segmentation maintains audio quality by preserving energy conservation in the binaural output while simplifying the decoder architecture.
Solution Approach 2:
The patent changes the approach from processing full multichannel signals to processing spatial parameters (inter-channel coherence, channel level difference) derived from downmixed signals. This parameter-based approach reduces decoder complexity while maintaining audio quality through proper HRTF filtering application.
3Speed
If HRTF filters are combined using non-energy-conserving upmixing, then processing speed is improved, but energy distribution accuracy deteriorates
Solution Approach 1:
The processing is segmented into fast spatial parameter calculation from downmixed signals and separate HRTF filtering for accurate binaural reconstruction. This segmentation achieves high processing speed in parameter extraction while ensuring energy distribution accuracy in the final binaural signal through energy-conserving HRTF filtering.
Solution Approach 2:
Spatial parameters serve as intermediaries that enable fast processing while preserving energy distribution accuracy. The inter-channel coherence and channel level difference parameters capture essential spatial and energy information, allowing rapid processing followed by accurate HRTF filtering to restore proper energy distribution in the binaural output.
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.