Surround Generation Apparatus for Compressed Audio Signal Processing
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Solution Overview
Problem
Existing surround sound generation systems from two-channel stereo signals often produce distorted signals with artifacts when decoding compressed audio, leading to poor sound quality due to compression effects.
Innovation Solution
A surround generation apparatus that decodes compressed audio, separates high-correlation and low-correlation components, and adjusts the mixing ratio and delay of the high-correlation component based on coding bit rate and method to minimize distortion and maintain a stable sense of expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a decorrelation process is performed on compressed audio signals to generate surround sound, then the sense of expansion is improved, but the sound quality deteriorates due to distortion and artifacts from compression
Solution Approach 1:
The patent segments the audio signal into high-correlation and low-correlation components. The high-correlation component (which contains compression artifacts) is separated from the low-correlation component (which contains the surround sound information). This segmentation allows the system to process different components differently - using the low-correlation component for surround sound generation while minimizing the impact of compression artifacts in the high-correlation component.
Solution Approach 2:
The patent extracts the high-correlation-component signal from the decoded audio signal. This extracted component, which contains the compression artifacts, is then processed separately through an addition unit that mixes it back in at controlled ratios. By taking out and separately managing the high-correlation component, the system can reduce its harmful effects while preserving the useful surround sound information in the low-correlation component.
2Manufacturing precision
If the high-correlation-component signal is added to the surround signal, then the sound quality is improved by reducing artifacts, but the sense of expansion is reduced
Solution Approach 1:
The patent employs dynamic control of the addition ratio between the high-correlation-component signal and the surround signal. The controller adjusts this ratio based on the bit rate of the encoded audio signal - using larger addition ratios for lower bit rates (which have more severe compression artifacts) and smaller ratios for higher bit rates. This dynamic adjustment allows the system to optimize both sound quality and sense of expansion according to the specific compression characteristics of the input signal.
Solution Approach 2:
The patent changes the addition ratio parameter based on the bit rate parameter. By varying this mixing parameter according to the compression level of the source material, the system can adaptively balance between reducing artifacts (favoring higher addition ratios) and maintaining sense of expansion (favoring lower addition ratios), achieving optimal performance across different audio compression scenarios.
3Device complexity
If a fixed addition ratio is used for the high-correlation-component signal, then the system complexity is reduced, but the adaptability to different coding bit rates deteriorates
Solution Approach 1:
The patent introduces dynamic control of the addition ratio based on the bit rate parameter. Rather than using a fixed ratio, the system adjusts the ratio according to the compression characteristics of the input signal. This dynamic approach increases system adaptability while the control logic remains relatively simple, managing the trade-off between complexity and versatility.
Solution Approach 2:
The patent implements parameter change by varying the addition ratio according to the bit rate. The controller receives the bit rate parameter from the decoded audio signal and adjusts the addition ratio accordingly. This parameter-based adaptation allows the system to handle different coding scenarios effectively without requiring complex reconfiguration, maintaining simplicity while achieving broad adaptability.
Data Source
AI summary
A surround system includes a decoder that decodes an encoded audio data stream, a decorrelation unit that receives and decorrelates stereo signals decoded by the decoder so as to generate surround signals having a low-correlation component, an addition unit that adds high-correlation-component signals extracted from the stereo signals to the surround signals generated by the decorrelation unit, and a controller that controls addition of the high-correlation-component signals performed by the addition unit on the basis of the bit rate of the audio data stream.