Stereo to 3D Audio Conversion via Ambient Decomposition
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Solution Overview
Problem
Existing methods for converting two-channel stereo content to 3D audio scene/object based content often compromise between audio image sharpness and spaciousness, leading to timbre and loudness artefacts, especially when altering the original spatial virtual position.
Innovation Solution
A method involving primary ambient decomposition to separate directional and ambient components, manipulating source directions, and encoding these components into Higher Order Ambisonics (HOA) format, while handling the centre channel as a static object, to maintain sharpness and spaciousness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two-channel stereo content is converted to 3D audio scene/object based content using existing methods, then the conversion is achieved, but timbre and loudness artefacts occur and audio image sharpness deteriorates
Solution Approach 1:
The audio signal is segmented into directional components and ambient components through primary ambient decomposition. This segmentation allows independent processing of each component type, enabling precise control over how directional signals are manipulated and how ambient signals are expanded, thereby maintaining audio image sharpness while achieving 3D conversion
Solution Approach 2:
The invention manipulates source direction parameters of directional components while preserving their essential characteristics. By carefully controlling parameter changes in the directional signal processing and using appropriate encoding schemes for HOA components, the method achieves spatial transformation without introducing timbre or loudness artefacts
2Adaptability or versatility
If source directions are manipulated to enhance spaciousness, then envelopment is improved, but audio image sharpness deteriorates
Solution Approach 1:
By separating directional and ambient components, the invention can manipulate ambient signals to enhance spaciousness and envelopment without affecting the clarity of directional information. The directional components maintain their original spatial characteristics for sharp direction identification, while ambient components are expanded to create immersive envelopment
Solution Approach 2:
The ambient component acts as an intermediary that enhances spaciousness and envelopment without directly interfering with directional signal integrity. By processing ambient signals separately and combining them with manipulated directional components, the system achieves both sharp direction identification and immersive envelopment
Data Source
AI summary
For generating 3D audio content from a two-channel stereo signal, the stereo signal (x(t)) is partitioned into overlapping sample blocks and is transformed into time-frequency domain. From the stereo signal directional and ambient signal components are separated, wherein the estimated directions of the directional components are changed by a predetermined factor, wherein, if changes are within a predetermined interval, they are combined in order to form a directional centre channel object signal. For the other directions an encoding to Higher Order Ambisonics HOA is performed. Additional ambient signal channels are generated by de-correlation and rating by gain factors, followed by encoding to HOA. The directional HOA signals and the ambient HOA signals are combined, and the combined HOA signal and the centre channel object signals are transformed to time domain.