Audio De-noising via Inter-frame Correlation for Missing Spectral Coefficients
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Solution Overview
Problem
Existing audio decoding systems face noise and poor acoustic effects due to mismatched and unquantized frequency bands, particularly when bit allocation is insufficient, leading to noise introduction during frequency band synthesis.
Innovation Solution
A signal de-noising method that selects spectral coefficients based on inter-frame correlation, performs weighting to predict and adjust spectral coefficients, and outputs the adjusted decoded signal to ensure adaptability and reduce noise, thereby improving the acoustic quality of the synthesized audio signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If quantization encoding is performed on high-frequency band spectra with limited bits, then code rate is reduced, but manufacturing precision deteriorates due to insufficient quantization precision in unquantized frequency bands
Solution Approach 1:
The patent introduces an intermediary processing step between dequantization and frequency band synthesis. Spectral coefficients from unquantized frequency bands are selected and used to fill gaps in the quantized spectra, serving as a mediator to bridge the precision gap caused by limited bit allocation.
Solution Approach 2:
The patent dynamically changes the parameter of spectral coefficient selection based on inter-frame correlation degree. When correlation is high, coefficients from previous frames are utilized to reconstruct missing spectral data, adapting the reconstruction process to temporal variations in the audio signal.
2Device complexity
If spectral coefficients are set to 0 or filled with noise in unquantized frequency bands, then device complexity is reduced, but object-generated harmful factors increase due to noise introduction during frequency band synthesis
Solution Approach 1:
The patent converts the harmful effect of missing spectral data into a benefit by utilizing the inter-frame correlation property. Instead of treating unquantized bands as empty or noisy, the method exploits temporal redundancy to reconstruct these bands, turning a limitation into an opportunity for improved quality.
Solution Approach 2:
The patent performs preliminary selection and preparation of spectral coefficients from unquantized frequency bands before the frequency band synthesis stage. By pre-processing and selecting appropriate coefficients based on inter-frame correlation, the method avoids the need for complex noise processing during synthesis.
3Manufacturing precision
If BWE spectra are retained in unquantized frequency bands, then manufacturing precision is maintained, but object-generated harmful factors increase due to mismatched position and energy information
Solution Approach 1:
The patent introduces dynamic adaptation by selecting spectral coefficients based on the degree of inter-frame correlation. The method dynamically adjusts which coefficients to use (from current frame, previous frame, or both) depending on the temporal characteristics of the audio signal, making the reconstruction process adaptive rather than static.
Solution Approach 2:
The patent segments the spectral coefficient selection process into different cases based on inter-frame correlation degree. It divides the frequency bands into quantized and unquantized portions, and further segments the unquantized bands into high-correlation and low-correlation regions, applying different reconstruction strategies to each segment.
Data Source
AI summary
In the field of audio encoding/decoding technologies, a signal de-noising method is provided. The method includes: selecting, according to a degree of inter-frame correlation of a frame where a spectral coefficient to be adjusted resides, at least two spectral coefficients having high correlation with the spectral coefficient to be adjusted; performing weighting on the at least two selected spectral coefficients and the spectral coefficient to be adjusted to acquire a predicted value of the spectral coefficient to be adjusted; and adjusting a spectrum of a decoded signal by using the acquired predicted value, and outputting the adjusted decoded signal. A signal de-noising apparatus corresponding to the signal de-noising method and an audio decoding system using the signal de-noising apparatus are also provided.