Stereo Signal Manipulation for Surround Sound Reproduction
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Solution Overview
Problem
Existing audio processing techniques fail to effectively generate a stereo output signal from a stereo input signal, particularly in surround systems, leading to inadequate reproduction of sound sources and ambient signals, and result in artifacts such as crosstalk and smearing of sound sources.
Innovation Solution
An apparatus that generates a stereo output signal by manipulating a combination signal derived from the input channels based on energy or amplitude values, using manipulation information to create distinct output channels that isolate and attenuate center-panned and ambient signal portions, and employing difference signals to remove sound sources equally present in both channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the first input signal is provided unaltered to a first group of loudspeakers and the second input signal unaltered to a second group, then the system is simple to operate, but the listener does not get the impression of real-life surround sound
Solution Approach 1:
The invention segments the stereo input signal into different components (center-panned signals, ambient signals, and side-panned signals) and routes them to different loudspeaker groups. The first group (front speakers) receives the left and right stereo channels, while the second group (surround speakers) receives processed signals with center-panned and ambient portions attenuated, creating a realistic surround sound experience without complex manual configuration
Solution Approach 2:
The invention introduces an intermediary processing stage that analyzes the stereo input signal and generates manipulated signals by attenuating specific components. This intermediary process automatically separates and routes different signal portions to appropriate loudspeaker groups, resolving the contradiction between operational simplicity and surround sound quality
2Device complexity
If both surround speakers are provided with the same signal, then the system is simple to configure, but sounds from the left should not be reproduced by the right surround speaker and vice versa
Solution Approach 1:
The invention applies asymmetric processing to the signals sent to left and right surround speakers. The left surround speaker receives a signal where the right channel's center-panned and ambient portions are attenuated, while the right surround speaker receives a signal where the left channel's center-panned and ambient portions are attenuated. This asymmetric approach ensures spatial accuracy without requiring complex manual configuration
Solution Approach 2:
The system dynamically processes the stereo input signal by continuously analyzing and manipulating the signal components in real-time. The processing adapts to the content of the input signal, automatically adjusting the attenuation of center-panned and ambient portions to achieve accurate spatial reproduction while maintaining simple configuration
3Device complexity
If center-panned signal components are reproduced by surround speakers, then the system maintains signal simplicity, but these components should not be reproduced by left and right surround speakers behind the listener
Solution Approach 1:
The invention extracts and attenuates center-panned signal components from the stereo input before sending signals to the surround speakers. By removing these components that should originate from front speakers, the system achieves accurate sound source localization without increasing overall signal processing complexity
Solution Approach 2:
The invention applies different processing qualities to different signal components and different loudspeaker groups. Center-panned and ambient portions are selectively attenuated for surround speakers while being preserved for front speakers, ensuring each loudspeaker group reproduces only the appropriate signal components for its spatial position
4Device complexity
If ambient signal portions are reproduced equally in both surround speakers, then the system is simple to implement, but the left and right ambient signal portions should be reproduced by their respective surround speakers
Solution Approach 1:
The invention applies asymmetric processing to ambient signal portions, where the left ambient signal is attenuated in the right surround channel and the right ambient signal is attenuated in the left surround channel. This creates spatially accurate ambient reproduction while maintaining relatively simple implementation
Solution Approach 2:
The invention segments ambient signal portions from the stereo input and routes them to the appropriate surround speakers with selective attenuation. This segmentation approach enables spatially accurate ambient reproduction without significantly increasing implementation complexity
Data Source
AI summary
An apparatus for generating a stereo output signal includes a manipulation information generator being adapted to generate manipulation information depending on a first signal indication value of a first input channel and on a second signal indication value of a second input channel, and a manipulator for manipulating a combination signal based on the manipulation information to obtain a first manipulated signal as a first output channel and a second manipulated signal as a second output channel. The combination signal is a signal derived by combining the first input channel and the second input channel. Furthermore, the manipulator is configured for manipulating the combination signal in a first manner, when the first signal indication value is in a first relation to the second signal indication value, or in a different second manner, when the first signal indication value is in a different second relation to the second signal indication value.