Surround Sound Generation Using Adaptive Filter Step Size
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Solution Overview
Problem
Conventional audio devices generating surround signals from 2-channel stereo signals can only produce a single set of surround signals, limiting the creation of spatially broad surround sound and requiring complex configurations to generate multiple sets, which complicates the process.
Innovation Solution
An audio device with multiple surround signal generation units that extract high-correlation components from L and R signals using adaptive filters with different step size parameters to generate distinct surround signals, allowing for varied sound effects by adjusting the level of subtraction and filter coefficient updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the same adaptive non-correlator processing is repeated to generate multiple surround signals, then the processing method remains simple, but the same surround signal is generated only, failing to provide spatially broad surround sound
Solution Approach 1:
The patent changes the step size parameter μ in the adaptive algorithm to generate different surround signals. By varying this parameter, multiple distinct surround signals can be produced from the same 2-channel stereo input without adding complex processing circuits. Each set of surround signal generation units uses a different step size parameter value, enabling diversity in the generated surround signals while keeping the overall system configuration relatively simple.
2Adaptability or versatility
If different processing circuits are added to generate multiple sets of surround signals, then spatially broad surround sound can be generated, but the configuration and process become complicated
Solution Approach 1:
The patent makes the adaptive non-correlator processing circuit multi-functional by allowing it to generate multiple different surround signals through parameter variation rather than requiring separate dedicated circuits for each surround signal set. The same processing circuit structure can produce different outputs by adjusting the step size parameter, thereby achieving versatility without proportionally increasing hardware complexity.
Solution Approach 2:
By varying the step size parameter μ, the system can generate multiple distinct surround signals using the same processing circuit architecture. This parameter-based differentiation allows one circuit to perform multiple functions that would otherwise require multiple separate circuits, reducing overall system complexity while maintaining the capability to provide spatially broad surround sound.
3Adaptability or versatility
If the step size parameter is kept uniform across all surround signal generation units, then the system configuration remains simple, but all units produce identical surround signals, limiting spatial coverage
Solution Approach 1:
The patent applies local quality by assigning different step size parameter values to different surround signal generation units. Each unit has a locally optimized parameter value that allows it to produce surround signals with specific characteristics suitable for its particular output channels. This localized parameter differentiation enables diverse surround signal generation while maintaining a relatively simple overall system structure.
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AI summary
An audio device (100) capable of generating two or more sets of surround signals based on 2-channel stereo signals, comprises an SL signal generation section (20) and a BL signal generation section (40) representing first surround signal generation units for receiving an L signal and an R signal of 2-channel stereo signals, extracting a component of the R signal having high correlation with the L signal and subtracting the component from the L signal, thereby generating a first surround signal; and an SR signal generation section (30) and a BR signal generation section (50) representing second surround signal generation units for extracting a component of the L signal having high correlation with the R signal and subtracting the component from the R signal, thereby generating a second surround signal. The level of subtracting a component from the L signal or the R signal for generating the first or second surround signal is differentiated between the plural sets.