Frame Error Concealment via Phase Matching and Smoothing

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Solution Overview

Problem

Existing audio encoding and decoding methods using time-frequency transform processing face challenges in minimizing sound quality deterioration due to frame errors without increasing complexity or introducing additional delay, especially when errors occur in partial frames of decoded audio signals.

Innovation Solution

A frame error concealment method that selects between phase matching and simple repetition modes based on frame states and phase matching flags for time domain error concealment, performing smoothing processing to reduce signal fluctuations and improve low-frequency band quality without additional delay or complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If regression analysis method is used for error frame concealment, then original energy is considered, but complexity increases when number of parameter types increases

Engineering Contradiction:

Improveerror concealment accuracyVSAvoidprocessing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the error concealment process into two distinct modes: frequency domain error concealment for spectral coefficients and time domain error concealment for time domain signals. This segmentation allows each mode to be optimized independently, reducing overall complexity while maintaining accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically selects between different error concealment methods based on frame characteristics (transient vs. non-transient frames). For transient frames, time domain concealment is used; for non-transient frames, frequency domain concealment is applied. This dynamic adaptation optimizes concealment accuracy without requiring complex processing for all frames.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If interpolation method is used for parameter prediction, then accuracy improves, but additional delay of one frame occurs

Engineering Contradiction:

Improveparameter prediction accuracyVSAvoidprocessing delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Instead of using future frames to predict current error frames (interpolation requiring future data), the patent inverts the approach by using past good frames to conceal current error frames through repetition and smoothing. This eliminates the need for future frame data, removing the additional delay while maintaining concealment accuracy.

Inventive Principle:

Principle #13The other way round (Inversion)

3Device complexity

If simple repetition method is used for error frame restoration, then complexity remains low, but reconstructed sound quality deteriorates due to OLA processing characteristics

Engineering Contradiction:

Improveprocessing complexityVSAvoidsound quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent creates a composite error concealment approach by combining frequency domain spectral coefficient repetition with time domain signal repetition and smoothing. This composite method leverages the advantages of both domains: frequency domain simplicity and time domain quality preservation, achieving good sound quality without excessive complexity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces smoothing processing as an intermediary step between simple repetition and final output. This intermediary smoothing operation reduces the harmful effects of OLA processing on repeated signals, improving sound quality while adding minimal complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If error concealment is applied to minimize sound quality deterioration, then adjacent frame quality improves, but processing complexity increases

Engineering Contradiction:

Improvesound qualityVSAvoiderror concealment complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies different error concealment strategies to different parts of the audio signal based on local characteristics. Transient frames receive time domain concealment with smoothing, while non-transient frames receive frequency domain concealment. This localized approach optimizes quality for each frame type without requiring complex processing for all frames.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10140994B2Frame error concealment method and apparatus, and audio decoding method and apparatus

Publication Date: 2018.11.27 SAMSUNG ELECTRONICS CO LTD

AI summary

Disclosed are a frame error concealment method and apparatus and an audio decoding method and apparatus. The frame error concealment (FEC) method includes: selecting an FEC mode based on at least one of a state of at least one frame and a phase matching flag, with regard to a time domain signal generated after time-frequency inverse transform processing; and performing corresponding time domain error concealment processing on the current frame based on the selected FEC mode, wherein the current frame is an error frame or the current frame is a normal frame when the previous frame is an error frame.