Binaural Rendering With Variable-Order FFT Subband Filtering
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Solution Overview
Problem
Binaural rendering for multi-channel audio signals requires high computational complexity, especially when using long binaural room impulse response (BRIR) filters, leading to inefficient processing and potential distortion, particularly in real-time environments.
Innovation Solution
The method involves truncating subband filter coefficients based on filter order information and performing fast Fourier transforms (FFT) on subband signals to reduce computational complexity, allowing for efficient binaural rendering by using truncated FFT filter coefficients and overlap-adding inverse transformed subframes.
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
Solution Approach 1:
The patent divides the long BRIR filter into multiple subband filters operating in parallel across different frequency bands. Each subband filter processes a specific frequency range, allowing the overall filtering operation to be performed with shorter individual filters while maintaining the effectiveness of the full-length BRIR filter.
Solution Approach 2:
The patent transitions from time-domain filtering to frequency-domain filtering using FFT (Fast Fourier Transform). By converting the filtering operation to the frequency domain, the patent achieves efficient implementation of long filter effects using shorter filters through modular subband processing, significantly reducing computational complexity.
2Adaptability or versatility
If the number of input channels increases, then audio format capability is improved, but computational complexity increases enormously
Solution Approach 1:
The patent processes each input channel through parallel subband filtering operations. By segmenting the processing into independent subband filters, the system can handle multiple channels simultaneously with reduced computational burden per channel, enabling support for high-channel-count formats like 22.2 channel audio.
Solution Approach 2:
The patent implements a universal subband filtering framework that can process any number of input channels through the same architectural structure. The modular design allows the system to adapt to different channel configurations (stereo, 5.1, 7.1, 22.2, etc.) without requiring fundamentally different processing approaches.
3Manufacturing precision
If time-domain binaural filtering is performed, then filtering accuracy is improved, but additional QMF synthesis operations are required
Solution Approach 1:
The patent inverts the traditional processing sequence by performing binaural filtering directly in the frequency domain (QMF domain) rather than in the time domain. This approach eliminates the need for separate QMF synthesis operations that would be required after time-domain filtering, as the filtering and synthesis operations are integrated into a single frequency-domain process.
Data Source
AI summary
The present invention relates to a method and an apparatus for binaural rendering an audio signal using variable order filtering in frequency domain. To this end, provided are a method for processing an audio signal including: receiving an input audio signal; receiving a set of truncated subband filter coefficients for filtering each subband signal of the input audio signal, the set of truncated subband filter coefficients being constituted by one or more FFT filter coefficients generated by performing FFT by a predetermined block size; generating at least one subframe for each subband; generating at least one filtered subframe for each subband; performing inverse FFT on the filtered subframe for each subband; and generating a filtered subband signal by overlap-adding the transformed subframe for each subband and an apparatus for processing an audio signal using the same.