Audio Signal Encoding Voiced Degree Factor Mechanical Sound Reduction
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Solution Overview
Problem
Current bandwidth extension technologies in the time domain for audio signals often result in a mechanical sound in restored high band signals due to strong harmonic components, which are not characteristic of authentic voice signals, leading to poor voice quality.
Innovation Solution
An audio signal encoding and decoding method that calculates a voiced degree factor from the low frequency encoding parameter, weights the high band excitation signal and random noise using this factor to generate a synthesized excitation signal, and adjusts parameters to reduce or eliminate mechanical sounds, thereby improving the encoding and decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional bandwidth extension technology is used to restore high band signal, then bandwidth is extended, but mechanical sound is introduced due to strong harmonic components
Solution Approach 1:
The patent modifies the excitation signal parameters by adjusting the voiced degree factor and weighting coefficients to reduce harmonic components in the high band signal. This involves changing the amplitude and spectral characteristics of the excitation signal based on the calculated voiced degree, thereby eliminating mechanical sound while preserving bandwidth extension
Solution Approach 2:
The patent introduces a voiced degree factor as an intermediary parameter that mediates between the low band encoding parameters and the high band excitation signal generation. This intermediary controls the weighting between periodic and aperiodic components, allowing smooth transition and reducing artificial harmonic artifacts in the restored high band signal
2Device complexity
If bandwidth extension is performed in time domain, then encoding complexity is reduced, but voice quality deteriorates due to strong harmonic components
Solution Approach 1:
The patent changes the excitation signal parameters by dynamically adjusting the voiced degree factor and weighting coefficients based on low band encoding parameters. This allows time domain processing to achieve better voice quality by controlling harmonic component strength while maintaining encoding simplicity
Solution Approach 2:
The patent makes the excitation signal generation dynamic by calculating the voiced degree factor in real-time and using it to adaptively weight the periodic and aperiodic components. This dynamic adjustment improves voice quality by matching the natural characteristics of speech signals while keeping the time domain processing approach computationally efficient
Data Source
AI summary
An audio signal encoding and decoding method, an audio signal encoding and decoding apparatus, a transmitter, a receiver, and a communications system, which can improve encoding and/or decoding performance. The audio signal encoding method includes dividing a to-be-encoded time domain signal into a low band signal and a high band signal; encoding the low band signal to obtain a low frequency encoding parameter; calculating a voiced degree factor, and predicting a high band excitation signal; weighting the high band excitation signal and random noise using the voiced degree factor, so as to obtain a synthesized excitation signal; and obtaining a high frequency encoding parameter based on the synthesized excitation signal and the high band signal. Technical solutions in the embodiments of the present invention can improve an encoding or decoding effect.