Lossy Compression Ambient Extraction for Multi-Channel Audio

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Solution Overview

Problem

Existing methods for upmixing mono audio signals to multi-channel systems lack an efficient way to generate ambient signals without additional information, often introducing synthetic effects or failing to separate localizable and non-localizable sound components effectively.

Innovation Solution

The method involves determining the difference between a compressed representation of an audio signal using lossy compression and its original representation to extract ambient signals, leveraging the fact that lossy compression preserves localizable sound events while attenuating non-localizable ambient components, thus generating an ambient signal that enhances auditory impression without additional information or synthetic effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If lossy compression is applied to extract ambient signals, then ambient signal extraction is achieved, but localizable sound events may be attenuated

Engineering Contradiction:

Improveambient signal extractionVSAvoidlocalizable sound event preservation

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The audio signal is segmented into localizable sound events and ambient components through lossy compression. The compression process naturally separates these components based on their different characteristics, with ambient signals being more susceptible to compression artifacts while localizable events are preserved more faithfully.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Compression parameters are optimized to achieve the right balance between extracting ambient signals and preserving localizable sound events. By adjusting compression ratios, bitrate, and encoding parameters, the system maximizes ambient signal extraction while maintaining the integrity of important sound events.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If synthetic effects are used to generate ambient signals, then ambient signal generation is achieved, but natural auditory impression is degraded

Engineering Contradiction:

Improveambient signal generationVSAvoidauditory impression quality

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The system uses the audio signal itself to generate ambient components through lossy compression, rather than introducing external synthetic effects. The compression process extracts ambient characteristics inherently present in the signal, ensuring natural auditory impressions without artificial additions.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If complex signal processing is applied to separate sound components, then separation precision is improved, but processing complexity increases

Engineering Contradiction:

Improvesound component separationVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Complex mechanical signal processing systems are replaced with lossy compression algorithms. The compression process inherently separates sound components through mathematical transformations and psychoacoustic models, achieving effective separation with simpler computational operations compared to traditional mechanical or electronic signal processing systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2500900B1Apparatus, method and computer program for deriving a multi-channel audio signal from an audio signal

Publication Date: 2014.04.02 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

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AI summary

An apparatus for deriving a multi-channel audio signal comprising a front-loudspeaker signal and a back-loudspeaker signal from an audio signal, the apparatus comprising an apparatus for generating an ambient signal from the audio signal, wherein the apparatus for generating the ambient signal from the audio signal comprises means for a lossy compression of a representation of the audio signal so as to obtain a compressed representation of the audio signal; and means for calculating a difference between the compressed representation of the audio signal and the representation of the audio signal so as to obtain a discrimination representation, the discrimination representation describing the difference between the representation of the audio signal and the compressed representation of the audio signal and describing those portions of the audio signal not played back in the lossily compressed representation, and wherein the means for lossy compression is configured such that signal portions exhibiting regular distribution of the energy or carrying a large signal energy are preferred to be included in the compressed representation; wherein the discrimination representation forms the ambient signal; an apparatus for providing the audio signal or a signal derived therefrom as the front-loudspeaker signal; and a back-loudspeaker-signal-providing apparatus for providing the ambient signal provided by the apparatus for generating the ambient signal or a signal derived therefrom as the back-loudspeaker signal. An apparatus for generating an ambient signal from an audio signal comprises means for lossy compression of a representation of the audio signal so as to obtain a compressed representation of the audio signal describing a compressed audio signal. The apparatus for generating the ambient signal further comprises means for calculating a difference between the compressed representation of the audio signal and the representation of the audio signal so as to obtain a discrimination representation. The apparatus further comprises means for providing the ambient signal using the discrimination representation.