3D Stereo Signal Synthesis via QMF Domain HRTF Application
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Solution Overview
Problem
Conventional audio coding methods for generating 3D signals are complex and degrade sound quality due to the need for repetitive domain transformations, making them unsuitable for mobile environments.
Innovation Solution
Applying the head-related transfer function (HRTF) within the quadrature mirror filter (QMF) domain to generate a simplified 3D signal using a surround data stream, transforming the downmixed signal into a sub-band filter domain and inverse transforming it to the time domain, thereby reducing complexity and improving sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional audio coding methods are used to generate 3D signals by transforming signals between time domain, QMF domain, and frequency domain, then the HRTF can be applied to generate stereo signals, but the processing complexity increases and sound quality degrades
Solution Approach 1:
The patent merges the QMF domain processing and HRTF application into a unified processing path. Instead of separately transforming signals between time domain, QMF domain, and frequency domain, the invention applies HRTF directly within the QMF domain, combining multiple transformations into a single integrated operation that reduces overall processing complexity while maintaining sound quality
Solution Approach 2:
The patent changes the domain parameter for HRTF application from frequency domain to QMF domain. By transforming the HRTF parameters into the QMF domain and applying them directly to QMF domain signals, the system eliminates the need for additional time-domain and frequency-domain transformations, thereby reducing processing complexity while preserving audio quality
2Reliability
If multiple domain transformations are performed to apply HRTF, then the stereo signal can be generated, but the processing time increases
Solution Approach 1:
The patent performs preliminary transformation of HRTF parameters into the QMF domain before signal processing. By pre-computing and storing the QMF domain HRTF parameters, the system eliminates the need for time-consuming real-time transformations during signal decoding, significantly reducing processing time while maintaining signal generation accuracy
Solution Approach 2:
The invention combines multiple sequential domain transformations into a single QMF domain operation. Instead of performing time-domain transformation, then frequency-domain transformation, then HRTF application, and finally inverse transformations, the system merges these operations into direct QMF domain processing, reducing total processing time
3Reliability
If separate QMF domain and frequency domain processing is performed, then the HRTF can be applied, but the number of processing steps increases
Solution Approach 1:
The patent extracts the HRTF application operation from the conventional sequence of separate time-domain and frequency-domain processing steps. By isolating and performing HRTF application directly in the QMF domain, the system removes unnecessary intermediate transformation steps while maintaining processing accuracy
Solution Approach 2:
The invention merges the QMF domain signal processing and HRTF application into a single integrated processing stage. This consolidation eliminates the need for separate time-domain transformations, frequency-domain transformations, and inverse transformations, reducing the total number of processing steps while maintaining signal processing accuracy
Data Source
AI summary
A method, medium, and system generating a 3-dimensional (3D) stereo signal in a decoder by using a surround data stream. According to such a method, medium, and system, a head related transfer function (HRTF) is applied in a quadrature mirror filter (QMF) domain, thereby generating a 3D stereo signal by using a surround data stream.