Multichannel Audio Phase Shifting for Precise Delay Reproduction
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Solution Overview
Problem
Existing signal processing technologies, such as those using decorrelators, fail to accurately reproduce phase or delay differences between channel signals, particularly in generating stereo signals from mono signals, leading to suboptimal sound quality.
Innovation Solution
A method and apparatus that shifts the phase of decoded audio or speech signals using phase shift information, incorporating phase shift information and estimated phase shift information generated through interpolation and smoothing in the frequency domain, to enhance sound quality by aligning phases across multiple channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a decorrelator is used to generate a stereo signal from a mono signal, then a stereo signal can be generated, but the phase or delay difference between channel signals cannot be precisely reproduced
Solution Approach 1:
The patent changes the parameter of phase shift information from being unavailable to being explicitly represented and transmitted. By introducing phase shift information as a separate parameter that can be encoded and decoded, the system achieves precise phase reproduction without relying solely on the decorrelator's indirect phase manipulation.
Solution Approach 2:
The patent introduces phase shift information as an intermediary element between the mono signal and the stereo signal generation process. This intermediary carries explicit phase relationship data that mediates the conversion process, allowing precise control over the phase and delay differences between channels rather than leaving it to the decorrelator's implicit processing.
2Reliability
If phase shift information is applied to parameter bands, then sound quality is enhanced, but the complexity of signal processing increases
Solution Approach 1:
The patent segments the frequency spectrum into multiple parameter bands and applies phase shift information selectively to each band. This segmentation allows the complex task of phase correction across the entire spectrum to be divided into manageable frequency-specific operations, reducing overall processing complexity while maintaining sound quality.
Solution Approach 2:
The patent applies different phase shift information to different parameter bands based on local requirements. Rather than applying a uniform phase correction across all frequencies, the system tailors the phase shift application to specific frequency regions where it is most needed, optimizing sound quality while minimizing unnecessary processing complexity.
Data Source
AI summary
A signal processing apparatus and method thereof are disclosed. The present invention includes receiving a low frequency downmix signal including a multi channel signal, phase shift information and spatial information corresponding to parameter band of the low frequency downmix signal, generating the multi channel signal by applying the spatial information based on the parameter band to a whole frequency downmix signal, generating estimated phase shift information of a parameter band by using the phase shift information, and generating a phase shift multi channel signal by shifting a phase of the multi channel signal based on the phase shift information and the estimated phase shift information. Accordingly, it is able to efficiently reproduce a phase or delay difference, which is difficult to be efficiently reproduced by a decorrelator, in a manner of shifting a phase of a decoded audio or speech signal based on phase shift information. And, a phase shift is enabled to fit each parameter band of a multi channel signal with raised coding efficiency.