Audio Channel Mapping with Equalization Filters
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Solution Overview
Problem
Existing audio reproduction technologies face challenges in preserving spatial diversity and envelopment when converting between different loudspeaker channel configurations, often resulting in a less enjoyable listening experience due to loss of acoustic channels and timbre differences during downmixing processes.
Innovation Solution
The application of an equalization filter to input channels, configured to boost specific spectral portions and compensate for timbre differences, helps preserve the spatial diversity and perceived location of sound sources, even when mapped to different output channels, by considering elevation angles and using measured binaural room impulse responses or empirical knowledge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If downmixing is applied to convert between different loudspeaker channel configurations, then the output channel configuration is achieved, but spatial diversity and timbre differences are lost
Solution Approach 1:
The patent applies different processing to different input channels based on their spatial characteristics. Specifically, it identifies whether input channels are from the same or different spatial locations and applies corresponding equalization filters to preserve local timbre characteristics while achieving the desired output configuration.
Solution Approach 2:
The patent changes the spectral parameters of audio signals by applying equalization filters that boost specific frequency ranges. This allows preservation of timbre characteristics associated with different spatial locations while performing the downmixing operation to achieve the target channel configuration.
2Manufacturing precision
If equalization filter is applied to preserve spatial diversity, then sound reproduction quality is improved, but processing complexity increases
Solution Approach 1:
The patent applies equalization filtering selectively rather than universally. It processes only those input channels that require timbre preservation based on their spatial characteristics, avoiding unnecessary processing of channels that don't require it, thus balancing quality improvement with processing efficiency.
Solution Approach 2:
The patent segments the audio processing into distinct pathways: one for channels requiring equalization filtering to preserve spatial timbre characteristics, and another for channels that can be directly mapped. This segmentation allows complex processing only where necessary.
Data Source
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AI summary
An apparatus for mapping a first input loudspeaker channel and a second input loudspeaker channel of an input loudspeaker channel configuration to at least one output loudspeaker channel of an output loudspeaker channel configuration, wherein each input loudspeaker channel and each output loudspeaker channel has a direction in which an associated loudspeaker is located relative to a central listener position, wherein the apparatus is configured to map the first input loudspeaker channel to a first output loudspeaker channel of the output loudspeaker channel configuration. The apparatus is further configured to map the second input loudspeaker channel to the first output loudspeaker channel, comprising processing the second input loudspeaker channel by applying at least one of an equalization filter and a decorrelation filter to the second input loudspeaker channel.