Sinusoidal Model Audio Frame Loss Concealment

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Solution Overview

Problem

Conventional audio frame loss concealment methods suffer from quality impairments, leading to audible signal discontinuities due to parameter freezing and extrapolation techniques, which are not universally applicable and may not guarantee smooth signal evolution.

Innovation Solution

A method involving sinusoidal analysis to identify frequencies of sinusoidal components, applying a sinusoidal model to create a substitution frame for lost audio frames, with enhanced frequency estimation and adaptation based on tonality, using techniques like main lobe approximation, harmonic enhancement, and interframe enhancement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If parameter freezing and extrapolation techniques are used for frame loss concealment, then the concealment can be performed with simple processing, but the signal evolution becomes discontinuous and audible quality deteriorates

Engineering Contradiction:

Improveconcealment processing simplicityVSAvoidsignal continuity and quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the approach from freezing/extrapolating parameters to using sinusoidal model parameters (frequency, amplitude, phase) that can evolve smoothly over time. The sinusoidal model allows continuous parameter changes while maintaining signal quality, resolving the contradiction between simple processing and signal continuity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic parameter evolution through the sinusoidal model, where frequency, amplitude, and phase can change continuously across frames. This dynamic approach replaces the static parameter freezing technique, enabling smooth signal transition while keeping the concealment mechanism relatively simple.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If conventional frame loss concealment methods are used, then the processing complexity is low, but audible signal discontinuities occur reducing quality

Engineering Contradiction:

Improveconcealment algorithm complexityVSAvoidaudible signal discontinuities

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent employs sinusoidal model parameters (frequency, amplitude, phase) that can evolve continuously, replacing conventional parameter freezing. This parameter change approach maintains low processing complexity while eliminating audible discontinuities through smooth signal transition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the mechanical parameter freezing approach with a sinusoidal model-based approach. This substitution replaces the rigid conventional method with a more flexible mathematical model that naturally produces continuous signal evolution, reducing harmful artifacts without significantly increasing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If parameter repetition techniques are used for frame loss concealment, then the method is codec-specific and hard to apply universally, but the signal evolution remains discontinuous

Engineering Contradiction:

Improvecodec compatibilityVSAvoidsignal evolution smoothness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent creates a universal frame loss concealment method based on the sinusoidal model that can be applied across different audio codecs. The sinusoidal parameter evolution mechanism is codec-independent, providing both broad adaptability and smooth signal evolution simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses sinusoidal model parameters that can be universally applied regardless of the specific codec. By changing from codec-specific parameter repetition to generic sinusoidal parameter evolution, the method achieves both versatility and smooth signal transition.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9478221B2Enhanced audio frame loss concealment

Publication Date: 2016.10.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method is provided for concealing a lost audio frame of a received audio signal by performing a sinusoidal analysis of a part of a previously received or reconstructed audio signal. The sinusoidal analysis involves identifying frequencies of sinusoidal components of the audio signal, and applying a sinusoidal model on a segment of the previously received or reconstructed audio signal. The segment is used as a prototype frame in order to create a substitution frame for a lost audio frame. The method includes creating the substitution frame for the lost audio frame by time-evolving sinusoidal components of the prototype frame, up to the time instance of the lost audio frame, in response to the corresponding identified frequencies. The method further includes performing at least one of an enhanced frequency estimation and an adaptation of the creating of the substitution frame in response to the tonality of the audio signal.