Spatial Audio Rendering from Stereo Downmix Signals
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Solution Overview
Problem
Current methods and apparatuses are unable to generate a surround signal with multi-channel features in environments capable only of producing mono or stereo signals, limiting the processing of media signals effectively.
Innovation Solution
A method and apparatus that utilize spatial information to convert a media signal into a surround signal by generating source mapping information, applying filter information for a surround effect, and integrating rendering information with a downmix signal to produce the surround signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional methods use spatial information to generate multi-channel signals, then multi-channel features are achieved, but the method is unusable in environments capable only of producing mono or stereo signals
Solution Approach 1:
The patent segments the surround signal generation process into two independent parts: (1) generating a downmix signal from multi-channel audio, and (2) generating a surround signal from the downmix signal using spatial information. This segmentation allows the system to work with mono or stereo downmix signals while still producing multi-channel surround output, resolving the contradiction between compatibility and capability.
Solution Approach 2:
The patent transforms the problem from a 2-channel (stereo) domain to a multi-channel domain by introducing virtual channels through spatial processing. By applying spatial information (such as inter-channel level difference, inter-channel time difference, and stereo width) to the downmix signal, the system creates additional spatial dimensions that enable surround sound reproduction in systems originally designed only for mono or stereo output.
2Device complexity
If a device generates only stereo signal, then device complexity is reduced, but the ability to generate surround signal is lost
Solution Approach 1:
The patent makes the downmix signal processing universal by designing it to accept both multi-channel and stereo/mono inputs while producing the same type of output suitable for surround generation. The spatial information processing module then applies the same surround generation algorithm regardless of the input type, enabling a single device architecture to serve multiple functions from simple stereo to complex surround sound.
Solution Approach 2:
The patent introduces spatial information as an intermediary element that bridges the gap between simple stereo downmix signals and complex surround output. By extracting or obtaining spatial information (CLD, ICT, SW) from the downmix signal and using it to modulate the signal generation process, the system enables surround effects without requiring complex multi-channel input processing.
Data Source
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AI summary
An apparatus for processing a media signal and method thereof are disclosed, by which the media signal can be converted to a surround signal by using spatial information of the media signal. The present invention provides a method of processing a signal, the method comprising of generating source mapping information corresponding to each source of multi-sources by using spatial information indicating features between the multi-sources; generating sub-rendering in¬ formation by applying filter information giving a surround effect to the source mapping in¬ formation per the source; generating rendering information for generating a surround signal by integrating the at least one of the sub-rendering information; and generating the surround signal by applying the rendering information to a downmix signal generated by downmixing the multi- sources.