Audio Format Transcoder Spatial Reproduction

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Solution Overview

Problem

Current audio encoding techniques struggle to accurately reproduce the spatial composition of multi-channel audio signals for arbitrary loudspeaker setups, as they often require specialized microphones with predetermined directivity patterns, which can degrade sound quality and limit flexibility in spatial reproduction.

Innovation Solution

The proposed solution combines Directional Audio Coding (DirAC) with Spatial Audio Object Coding (SAOC) to efficiently convert directional audio components into separated audio source measures, using DirAC as an acoustic front-end for spatial filtering and SAOC for rendering, allowing for flexible spatial reproduction on various loudspeaker configurations without altering the downmix signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If specialized microphones with predetermined directivity patterns are used, then spatial reproduction accuracy is improved, but sound quality is degraded and flexibility is limited

Engineering Contradiction:

Improvespatial reproduction accuracyVSAvoidsound quality

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an acoustic front-end as an intermediary component that processes the microphone signal before transmission. This front-end performs spatial filtering and directional audio coding to extract spatial information without requiring specialized microphones, thereby maintaining sound quality while achieving accurate spatial reproduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical solution of using specialized microphones with predetermined directivity patterns with a signal processing approach. By using ordinary microphones combined with acoustic front-end processing (directional audio coding, spatial filtering), the system achieves the same spatial reproduction accuracy without the quality degradation associated with specialized hardware.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If DirAC is used for spatial filtering, then directional audio components are extracted, but computational complexity increases

Engineering Contradiction:

Improvedirectional audio component extractionVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the audio processing into distinct stages: acoustic front-end processing for spatial filtering, SAOC encoding for compression, and decoder processing for reconstruction. This segmentation allows optimization of each stage independently, reducing overall computational complexity while maintaining directional audio component extraction accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The acoustic front-end performs preliminary spatial filtering and directional audio coding before the main encoding process. By extracting and processing directional information in advance, the system reduces the computational burden on subsequent encoding and decoding stages.

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If SAOC is used for audio object coding, then bitrate efficiency is improved, but reproduction flexibility for arbitrary loudspeaker setups is reduced

Engineering Contradiction:

Improvebitrate efficiencyVSAvoidreproduction flexibility

Core Design Contradiction:

Loss of energyVSAdaptability or versatility

Solution Approach 1:

The patent enhances SAOC to support arbitrary loudspeaker setups by making the rendering process adaptable to different spatial configurations. The system maintains bitrate efficiency through parametric coding while adding flexibility to reproduce audio objects on various loudspeaker arrangements, including non-standard configurations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Measurement precision

If 5.1 loudspeaker setup is used, then spatial reproduction is improved, but adaptability to other loudspeaker configurations is lost

Engineering Contradiction:

Improvespatial reproductionVSAvoidadaptability to loudspeaker configurations

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic rendering that adapts to different loudspeaker configurations. Rather than being fixed to a 5.1 setup, the system can dynamically adjust the spatial reproduction parameters to match various loudspeaker arrangements, maintaining spatial reproduction quality across different configurations.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8891797B2Audio format transcoder

Publication Date: 2014.11.18 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

AI summary

An audio format transcoder for transcoding an input audio signal, the input audio signal having at least two directional audio components. The audio format transcoder including a converter for converting the input audio signal into a converted signal, the converted signal having a converted signal representation and a converted signal direction of arrival. The audio format transcoder further includes a position provider for providing at least two spatial positions of at least two spatial audio sources and a processor for processing the converted signal representation based on the at least two spatial positions to obtain at least two separated audio source measures.