QMF Subband Binaural Filtering for Low-Complexity Audio Rendering
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Solution Overview
Problem
Binaural rendering for multi-channel signals in stereo requires high computational complexity, especially with long binaural room impulse response (BRIR) filters, leading to inefficient processing and potential sound quality loss.
Innovation Solution
The method involves performing binaural rendering in the QMF domain using truncated BRIR filters, separating filter coefficients into front and late reverberation parts, and applying fast convolution and QTDL processing to reduce computational complexity while maintaining sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If long BRIR filters are used for binaural rendering, then sound quality is improved, but computational complexity increases significantly
Solution Approach 1:
The patent divides the long BRIR filter into multiple subband filters in the QMF domain. Each subband filter operates on a specific frequency range, allowing parallel processing that reduces overall computational complexity while maintaining the effective length needed for sound quality
Solution Approach 2:
The patent transforms the time-domain convolution problem into the QMF (Quadtree-Mirror Filter) domain, changing the processing dimension from time to frequency-subband. This allows efficient filtering of multi-channel signals by operating in the subband domain where computational operations are more manageable
2Adaptability or versatility
If the number of input channels increases, then multi-channel audio capability is improved, but computational complexity becomes enormous
Solution Approach 1:
The patent applies subband decomposition to separate the multi-channel signal processing into multiple frequency bands. Each subband can be processed independently and in parallel, reducing the computational burden per channel while maintaining support for many input channels
Solution Approach 2:
The patent combines multiple subband processing results to reconstruct the final binaural output. By merging the processed subbands through QMF synthesis, the system achieves efficient multi-channel rendering without requiring separate full-length filter operations for each channel
3Speed
If fast convolution with FFT is used, then convolution speed is improved, but computational complexity increases due to multiple FFT operations
Solution Approach 1:
The patent extracts the convolution operation from the time domain and performs it directly in the QMF domain. This eliminates the need for multiple FFT and inverse FFT operations required by traditional fast convolution methods, reducing computational complexity while maintaining processing efficiency
Solution Approach 2:
The patent uses pre-computed QMF domain subband filters that capture the BRIR characteristics. These filtered templates are applied directly to the input channels in the QMF domain, avoiding repeated FFT operations and reducing real-time computational burden
4Manufacturing precision
If QMF synthesis is performed for each channel, then binaural filtering in QMF domain is achieved, but processing efficiency decreases
Solution Approach 1:
The patent merges the filtering operations across multiple channels by processing subbands in parallel and combining results through QMF synthesis. This unified approach maintains accurate binaural filtering while improving efficiency by avoiding separate time-domain processing for each channel
Data Source
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AI summary
The present invention relates to a method and an apparatus for processing a signal, which are used for effectively reproducing a multimedia signal, and more particularly, to a method and an apparatus for processing a signal, which are used for implementing filtering for multimedia signal having a plurality of subbands with a low calculation amount. To this end, provided are a method for processing a multimedia signal including: receiving a multimedia signal having a plurality of subbands; receiving at least one proto-type filter coefficients for filtering each subband signal of the multimedia signal; converting the proto-type filter coefficients into a plurality of subband filter coefficients; truncating each subband filter coefficients based on filter order information obtained by at least partially using characteristic information extracted from the corresponding subband filter coefficients, the length of at least one truncated subband filter coefficients being different from the length of truncated subband filter coefficients of another subband; and filtering the multimedia signal by using the truncated subband filter coefficients corresponding to each subband signal and an apparatus for processing a multimedia signal using the same.