Multichannel Audio Predictive Decoding with Error Recovery

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Solution Overview

Problem

Predictive coding schemes in stereo and multichannel audio are sensitive to errors, leading to error propagation and inefficient bandwidth usage, especially in error-free channels.

Innovation Solution

Implement a method and apparatus that replace decoded parameters with estimated parameters in a decoder based on the last observed active source, using a parameter stability measure to determine when to activate parameter recovery, and switch between predictive and absolute decoding modes to reduce error propagation and bandwidth waste.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If predictive coding schemes are used in multichannel audio, then bandwidth efficiency is improved, but error propagation occurs leading to degraded audio quality

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoidaudio quality

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The system dynamically switches between predictive coding mode (for bandwidth efficiency) and absolute coding mode (for error recovery). A stability measure is calculated to determine when to activate parameter recovery, allowing the system to adapt its coding strategy based on current audio scene stability and error conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the coding parameter mode based on stability assessment. When the stability measure indicates unstable audio scenes, the system activates parameter recovery by switching to absolute coding mode, thereby preventing error propagation while maintaining bandwidth efficiency during stable scenes

Inventive Principle:

Principle #35Parameter changes

2Reliability

If parameter recovery is activated to reduce error propagation, then audio quality is improved, but bandwidth consumption increases

Engineering Contradiction:

Improveaudio qualityVSAvoidbandwidth consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Parameter recovery is dynamically activated only when the stability measure indicates unstable audio scenes or error conditions are detected. During stable scenes, the system remains in predictive coding mode, minimizing bandwidth consumption while maintaining audio quality

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes coding parameters based on stability assessment. The stability measure triggers parameter recovery only when necessary, switching between predictive and absolute coding modes to optimize the trade-off between audio quality and bandwidth consumption

Inventive Principle:

Principle #35Parameter changes

3Reliability

If absolute coding mode is used to prevent error propagation, then audio quality is maintained, but bandwidth efficiency decreases

Engineering Contradiction:

Improveaudio qualityVSAvoidbandwidth efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system dynamically selects between absolute coding mode and predictive coding mode based on real-time stability assessment. Absolute coding is used only when instability is detected or errors occur, while predictive coding is used during stable scenes to maintain bandwidth efficiency

Inventive Principle:

Principle #15Dynamics

4Loss of energy

If predictive decoding mode is used to save bandwidth, then bandwidth efficiency is improved, but error propagation and freezing of audio scene occur during errors

Engineering Contradiction:

Improvebandwidth efficiencyVSAvoiderror propagation

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system uses a stability measure as feedback to monitor audio scene stability and error conditions. This feedback mechanism triggers parameter recovery when instability is detected, preventing error propagation while maintaining bandwidth efficiency during normal operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The decoding mode dynamically switches between predictive and absolute modes based on stability feedback. This allows the system to prevent error propagation during unstable scenes while maintaining bandwidth efficiency during stable scenes

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP3948857B1Method and apparatus for error recovery in predictive coding in multichannel audio frames

Publication Date: 2025.09.17 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A method, apparatus and decoder for replacing decoded parameters in a received multichannel signal in which a frame of consecutive frames of the received multichannel signal is decoded and responsive to receiving a previous frame bad frame indicator while operating in a predictive decoding mode with a current frame of the consecutive frames, it is determined whether a parameter stability measure is below a threshold. Responsive to the parameter stability measure being below the threshold a parameter recovery is activated by retrieving the estimated parameters and replacing decoded parameters of the current frame with the estimated parameters. Otherwise, it is detected whether a source is an active source and responsive to the source being an active source, decoded parameters of the current frame are stored as estimated parameters and the parameter stability measure is determined.