Adaptive Send Effect Processing for MPEG Surround Externalization

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Solution Overview

Problem

MPEG Surround binaural decoding in Low Power mode lacks natural externalization due to incomplete representation of HRTF data, leading to unrealistic surround experiences when using send effects like reverberation, as the existing methods result in uneven reverberation strength across channels.

Innovation Solution

Compensating for unequal weighting of component signals by applying send effects adaptively based on parameters representing dependencies between weighted component signals, allowing for proportional effect strengths across channels, thereby enhancing the realism of the surround experience.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If parallel reverberation is added to compensate for lack of externalization in Low Power mode, then externalization is improved, but the binaural output sounds too reverberant when original content is primarily present in the center channel

Engineering Contradiction:

ImproveexternalizationVSAvoidexcessive reverberation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies different reverberation gains to different channels based on their weighting parameters. Center channels receive lower reverberation gains while surround channels receive higher gains, creating local quality differences that prevent excessive reverberation in center-dominated content while maintaining externalization benefits.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts the reverberation gain parameter for each channel based on the weighting parameters of the downmix matrix. By changing these parameters adaptively, the system compensates for the unequal weighting of component signals and achieves balanced externalization without excessive reverberation.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If send effects are applied to the downmix signal in Low Power mode, then processing complexity is reduced, but unequal weighting of component signals causes unrealistic surround experience

Engineering Contradiction:

Improveprocessing complexityVSAvoidsurround experience realism

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses the weighting parameters from the downmix matrix to adjust send effect gains for different channels. This parameter-based approach maintains low processing complexity while achieving realistic surround experience by compensating for unequal channel weighting without requiring full multi-channel processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The weighting parameters serve as intermediaries that convey information about channel importance from the downmix process to the send effect processing. These parameters enable the system to make informed gain adjustments without requiring complex analysis of the original multi-channel signal.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9591424B2Generating an output signal by send effect processing

Publication Date: 2017.03.07 KONINKLIJKE PHILIPS NV

AI summary

An output signal is generated from an input signal by applying a send effect processing to the input signal. The input signal comprises a weighted sum of component signals. Dependencies between the weighted component signals are represented by parameters. In accordance with the present invention, the output signal is generated in dependence of the parameters to compensate for an unequal weighting of component signals comprised in the input signal. Due to this compensation the strength of the send effect corresponding to the separate component signals is (nearly) proportional to the strength of each of the component signals, which results in more realistic surround experience.