Spatial Audio Signal Decoding for Loudspeaker Layout Adaptation

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Solution Overview

Problem

Existing spatial audio technologies face challenges in accurately reproducing the spatial distribution of sound energy and preserving the original artistic intent when converting between different loudspeaker configurations, leading to a loss of information and suboptimal reproduction quality.

Innovation Solution

The apparatus and method for spatial audio signal decoding, which synthesizes output audio signals by dividing the input signal into direct and diffuse parts based on spatial metadata, adjusts gains and speaker layouts to match the energy distribution of the original surround mix, and employs vector base amplitude panning to position sound in 3D space, ensuring accurate reproduction across various loudspeaker configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If spatial audio signals are converted between different loudspeaker configurations using existing technologies, then the conversion process can be performed, but the spatial distribution of sound energy is not accurately reproduced and information is lost

Engineering Contradiction:
Improveaccuracy of spatial sound energy distributionVSAvoidinformation loss during configuration conversion
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The audio signal is divided into direct sound components and diffuse sound components. The direct sound part contains directional information about sound sources, while the diffuse sound part contains ambient spatial information. This segmentation allows each component to be processed and reproduced with appropriate spatial characteristics, improving overall spatial accuracy without information loss.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses spatial metadata parameters including direct-to-total energy ratio, direction parameters, and loudspeaker layout parameters to control the reproduction process. By adjusting these parameters based on the input and output loudspeaker configurations, the system accurately reproduces the spatial distribution of sound energy while preserving all original information.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If spatial audio signals are converted between different loudspeaker configurations, then format flexibility is achieved, but the original artistic intent is not preserved

Engineering Contradiction:
Improveloudspeaker configuration flexibilityVSAvoidpreservation of original artistic intent
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system incorporates loudspeaker layout parameters that describe the original loudspeaker configuration into the spatial metadata. During reproduction, this information provides feedback to the rendering process, allowing the system to adapt to different output configurations while maintaining fidelity to the original artistic intent through iterative optimization of the spatial distribution.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

By using adjustable spatial metadata parameters including direct-to-total energy ratio and direction parameters, the system can dynamically adapt the reproduction to match the original artistic intent regardless of the output loudspeaker configuration. These parameters enable flexible format conversion while preserving the creator's spatial audio vision.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If conventional spatial audio decoding is used, then processing simplicity is maintained, but reproduction quality is suboptimal

Engineering Contradiction:
Improveprocessing simplicityVSAvoidreproduction quality
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The decoding process segments the audio signal into direct and diffuse components that are processed through separate synthesis paths. This segmentation improves reproduction quality by applying appropriate spatial processing to each component while maintaining a relatively simple overall structure that can be implemented in standard audio decoders.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The spatial audio decoder uses a universal set of spatial metadata parameters that work across different loudspeaker configurations and audio formats. This multi-functionality allows the same decoding process to achieve high reproduction quality regardless of the input format or output configuration, simplifying implementation while maintaining excellence.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3777242B1Spatial sound rendering
Publication Date: 2023.10.11 NOKIA TECHNOLOGIES OY
  • EP3777242B1 patent drawingFigure 1
  • EP3777242B1 patent drawingFigure 2
  • EP3777242B1 patent drawingFigure 3a

AI summary

An apparatus for spatial audio signal decoding associated with a plurality of speaker nodes placed within a three dimensional space, the apparatus comprising at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: receive: at least one associated audio signal, the associated audio signal based on a defined speaker layout audio signal (310); spatial metadata associated with the associated audio signal (306; 308); at least one parameter representing a defined speaker layout associated with the defined speaker layout audio signal (304); and at least one parameter representing an output speaker layout (452); synthesize from the at least one associated audio signal at least one output audio signal based on the spatial metadata and the at least one parameter representing the defined speaker layout and the at least one parameter representing an output speaker layout (421).