Poly-phase filter up-sampling for audio band expansion
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Solution Overview
Problem
Existing techniques for expanding audio frequency bands, such as combining band expansion and up-sampling, result in high-quality sound but require a significant processing amount, which can be impractical for certain applications.
Innovation Solution
A frequency band expanding device and method that uses a poly-phase configuration filter to perform up-sampling and level adjustment of low band sub band signals, generating high band signals with a small processing amount by extracting and adding low band signals to high band signals, and optionally includes noise generation for natural sound enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If band expansion technique and up-sampling are combined to expand frequency band, then high-quality sound is obtained, but processing amount is correspondingly increased
Solution Approach 1:
The patent divides the frequency band into multiple sub-bands (low band and high band) and processes them separately. The low band signal is extracted, up-sampled, and then combined with the high band signal. This segmentation allows efficient processing by handling different frequency ranges independently, reducing overall processing complexity while maintaining audio quality.
Solution Approach 2:
The patent changes the sampling rate parameter by performing up-sampling on the low band signal from a lower sampling rate to a higher sampling rate. This parameter change enables the low band signal to be processed at the target high resolution, and when combined with the high band signal, produces high-quality output without requiring the entire signal to be processed at high resolution throughout.
2Manufacturing precision
If up-sampling is performed on audio signal before band expansion, then high resolution sound is obtained, but computational resources required increase
Solution Approach 1:
The patent segments the audio signal processing into separate low band and high band pathways. Up-sampling is applied only to the low band signal, not the entire audio signal. This selective approach reduces computational resource requirements while still achieving high resolution in the final combined output.
Solution Approach 2:
The patent performs up-sampling on the low band signal in advance before combining it with the high band signal. This preliminary action ensures that the low band component is at the required high resolution before the final combination, avoiding the need to process and combine large amounts of high-resolution data throughout the entire processing chain.
Data Source
AI summary
The present technology relates to a device, a method, and a program for expanding a frequency band, which are capable of obtaining high-quality sound with a small processing amount. A low band extraction band-pass filter processing unit passes a predetermined band of a low band of an input signal and generates a low band sub band signal. A band-pass filter calculation circuit calculates band-pass filter coefficients of band-pass filters having sub bands of high bands as a pass band based on an estimate value of high band sub band power, and an addition unit obtains one filter coefficient by adding the band-pass filter coefficients. A poly-phase configuration level adjustment filter performs up-sampling and level adjustment by performing filtering on a flattened signal obtained from a low band sub band signal using the filter coefficient obtained by the addition unit, and generates a high band signal. An addition unit obtains an output signal by adding the high band signal to the low band signal. The present technology can be applied to a frequency band expanding device.