Audio Encoder Adaptive Mixing Ratio for Stereo Noise Reduction
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Solution Overview
Problem
Existing audio encoders face challenges in maintaining sound quality when encoding stereo audio signals with high efficiency, particularly when the audio signals from different channels are significantly different, leading to noise and instability in decoding.
Innovation Solution
An audio encoder that determines a mixing ratio based on the frequency spectra of multiple channels to adaptively mix and encode the frequency spectra, preventing deterioration of sound quality by ensuring optimal mixing ratios for each channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If intensity stereo encoding is applied to enhance encoding efficiency, then encoding efficiency is improved, but artificial noise arises in decoding when audio signals of different channels are significantly different
Solution Approach 1:
The patent dynamically changes the mixing ratio parameter based on the correlation between left and right channel signals. When correlation is high, a higher mixing ratio is applied to enhance encoding efficiency; when correlation is low, the mixing ratio is reduced to prevent artificial noise, thus adapting the encoding approach to the actual signal characteristics
Solution Approach 2:
The patent introduces dynamic switching between different encoding modes (intensity stereo encoding and dual channel encoding) based on the calculated correlation value. This dynamic adaptation allows the system to optimize encoding efficiency when channels are similar while preventing noise when channels are significantly different
2Productivity
If M/S stereo encoding is applied when audio signals of different channels are similar, then encoding efficiency is improved, but quantization noise occurs when audio signals of different channels are significantly different
Solution Approach 1:
The patent calculates the correlation between left and right channel signals as feedback to determine the appropriate encoding mode and mixing ratio. This feedback mechanism ensures that the encoding strategy is continuously adapted based on the actual relationship between channels, preventing both quantization noise and artificial noise while maintaining encoding efficiency
3Productivity
If encoding is frequently switched between common encoding and intensity stereo encoding, then encoding efficiency is optimized for different signal conditions, but sensing positions become unstable or abnormal sound arises
Solution Approach 1:
The patent calculates the correlation between channels in advance to determine the appropriate encoding mode and mixing ratio before actual encoding. This preliminary determination prevents frequent switching during encoding, ensuring stable sensing positions and avoiding abnormal sound while still optimizing encoding efficiency based on signal characteristics
Data Source
AI summary
There is provided an audio encoder comprising a determination part determining, based on frequency spectra of audio signals of a plurality of channels, a mixing ratio as a ratio, relative to a frequency spectrum after mixing for each channel of the plurality of channels, of the frequency spectrum for another channel, a mixing part mixing the frequency spectra of the plurality of channels for each channel based on the mixing ratio determined by the determination part, and an encoding part encoding the frequency spectra of the plurality of channels after mixing by the mixing part.