Audio Decoding with Spectral Band Expansion for Low-Delay Sound
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Solution Overview
Problem
Existing audio decoding technologies in resource-poor settings face challenges in achieving high-quality sound due to increased delay and resource usage caused by band expansion processes, particularly when dealing with signals having high tonality or energy concentration at specific frequencies.
Innovation Solution
A decoding device and method that calculates pseudo amplitude spectra from MDCT spectra to extract feature quantities, allowing for high-band level adjustment based on spectral characteristics, reducing delay and resource usage while maintaining sound quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If band expansion processes (filtering, band dividing, band combining) are used to achieve high-quality sound, then sound quality is improved, but time delay increases and resource consumption increases
Solution Approach 1:
The patent extracts only the essential spectral characteristics (amplitude information) needed for band expansion, rather than performing complete filtering and band combining operations. By taking out only the necessary spectral features and using them to synthesize the high-band signal, the system achieves sound quality improvement without the time delay and resource consumption of traditional filtering methods
Solution Approach 2:
The patent replaces the mechanical filtering system (band dividing filter and band combining filter) with a spectral manipulation approach. Instead of using physical filters to divide and combine bands, the system operates directly in the frequency domain by manipulating spectral components, thereby eliminating the time delay and computational overhead associated with traditional filtering operations
2Manufacturing precision
If band expansion processes (filtering, band dividing, band combining) are used to achieve high-quality sound, then sound quality is improved, but device complexity and resource usage increase
Solution Approach 1:
The patent extracts only the essential spectral characteristics (amplitude information) needed for band expansion, rather than performing complete filtering and band combining operations. By taking out only the necessary spectral features and using them to synthesize the high-band signal, the system achieves sound quality improvement without the time delay and resource consumption of traditional filtering methods
Solution Approach 2:
The patent replaces the mechanical filtering system (band dividing filter and band combining filter) with a spectral manipulation approach. Instead of using physical filters to divide and combine bands, the system operates directly in the frequency domain by manipulating spectral components, thereby eliminating the time delay and computational overhead associated with traditional filtering operations
3Manufacturing precision
If amplitude of expanded band spectrum is adjusted using MDCT spectrum, then spectral characteristics are improved, but phase component and mutual phase relationship are disturbed
Solution Approach 1:
The patent extracts only the amplitude information from the MDCT spectrum, deliberately separating and discarding the phase component. By taking out only the necessary amplitude characteristics for spectral shaping and ignoring the phase information, the system achieves improved spectral characteristics while accepting phase loss, which is then compensated through alternative means in the band expansion process
Data Source
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AI summary
The present technology relates to an encoding device and a method, a decoding device and a method, and a program that enables acquisitions of high-quality sound even in a resource-poor setting. A demultiplexer demultiplexes a supplied code string, to obtain the quantized low-band spectrum, the spectral characteristic code, and the quantized expansion coefficient(s). At this point, the code string includes a single quantized expansion coefficient or quantized expansion coefficients of the respective bands in the high band depending on the spectral characteristic code. A spectral inverse quantization unit obtains the low-band spectrum by inversely quantizing the quantized low-band spectrum. An expansion coefficient inverse quantization unit obtains the expansion coefficient(s) by inversely quantizing the quantized expansion coefficient(s). An expanded spectrum generation unit generates an expanded spectrum, in accordance with the low-band spectrum and the expansion coefficient(s) depending on the spectral characteristic code. An IMDCT unit generates a band-expanded time-series signal from the low-band spectrum and the expanded spectrum. The present technology can be applied to decoding devices.