Transform-Decoded Audio Pre-Echo Attenuation Across Frequency Bands
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Solution Overview
Problem
Current digital audio signal decoding methods suffer from pre-echo noise, particularly in transform coding, where abrupt signal transitions lead to noise distribution across the entire decoding window, causing audible distortion and degrading audio quality.
Innovation Solution
A method for pre-echo attenuation in digital audio signals involves decomposing the decoded signal into sub-signals based on a predetermined criterion, calculating attenuation factors for each sub-signal, and applying these factors to the pre-echo area to reduce noise effectively without requiring additional auxiliary information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transform coding with long windows is used to increase coding gain, then coding efficiency is improved, but pre-echo noise becomes more prominent
Solution Approach 1:
The decoded signal is decomposed into multiple sub-signals based on frequency characteristics (e.g., low-frequency and high-frequency components). This segmentation allows different attenuation factors to be applied to different frequency bands, enabling precise control over pre-echo noise reduction while preserving coding efficiency achieved through long-window transform coding.
Solution Approach 2:
Different attenuation factors are calculated and applied to different sub-signals based on their specific frequency characteristics and energy distribution. This local quality approach ensures that attenuation is adapted to each frequency band's needs, effectively reducing pre-echo noise in high-frequency regions while maintaining low-frequency signal integrity and overall coding performance.
2Object-affected harmful factors
If uniform attenuation is applied to reduce pre-echo noise, then noise reduction is achieved, but frequency-specific characteristics are lost
Solution Approach 1:
The signal is divided into frequency-based sub-signals, allowing the attenuation process to be customized for each frequency band. This segmentation enables the system to adapt to different frequency characteristics rather than applying a one-size-fits-all attenuation approach.
Solution Approach 2:
Each sub-signal receives a specifically calculated attenuation factor based on its frequency characteristics and energy distribution. This local quality ensures that the attenuation is tailored to each frequency band's specific needs, preserving the adaptability and frequency-specific characteristics of the original signal while effectively reducing pre-echo noise.
3Measurement precision
If attenuation factors are calculated per sample to precisely control noise reduction, then noise attenuation precision is improved, but computational complexity increases
Solution Approach 1:
The signal is segmented into a smaller number of frequency-based sub-signals rather than processing each sample independently. This segmentation reduces the total number of attenuation factors that need to be calculated and stored, thereby reducing computational complexity while still providing precise control over noise attenuation through frequency-specific processing.
Data Source
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AI summary
The invention relates to a method for processing the attenuation of pre-echo in a digital audio signal decoded by transform decoding. Said method comprises the following steps: decomposition (E603) of the decoded signal into at least two sub-signals according to a pre-determined decomposition criterion; calculation (E604) of attenuation factors per sub-signal and per sample of a previously determined pre-echo zone; attenuation (E605) of pre-echo in the pre-echo zone of each of the sub-signals by applying attenuation factors to the sub-signals; and production (E606) of the attenuated signal by addition of the attenuated sub-signals. The invention also relates to a processing device implementing the steps of the described method, and to a decoder comprising such a device.