Inter-Channel Phase Encoding with Adaptive Subband Selection

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Solution Overview

Problem

Existing stereo audio encoding methods face inefficiencies in calculating inter-channel phase difference (IPD) parameters, either consuming excessive resources or compromising phase information precision and encoding quality.

Innovation Solution

An adaptive IPD parameter encoding method that determines an encoding scheme based on reference parameters such as signal characteristics and previous frames, employing time-frequency transformation and selective encoding strategies to optimize resource use and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If IPD parameters of all subbands are calculated one by one, then phase information precision is improved, but encoding efficiency deteriorates due to excessive resource occupation

Engineering Contradiction:
Improvephase information precisionVSAvoidencoding efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The frequency domain signal is divided into multiple subbands, and IPD parameters are calculated for each subband separately. This segmentation allows precise phase information extraction while enabling selective processing - only subbands requiring high precision undergo full IPD calculation, resolving the contradiction between precision and efficiency

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of calculating IPD parameters for all subbands uniformly, the patent applies partial action by selectively calculating IPD parameters only for specific subbands based on signal characteristics. This reduces overall computational load while maintaining necessary precision where required

Inventive Principle:
Principle #16Partial or excessive action

2Productivity

If only group IPD parameter is calculated for the entire frame, then resource occupation is reduced, but phase information precision deteriorates

Engineering Contradiction:
Improveencoding efficiencyVSAvoidphase information precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the frequency spectrum into multiple subbands and calculates IPD parameters for each subband individually rather than computing a single group IPD for the entire frame. This segmentation preserves phase information precision across different frequency regions while maintaining computational efficiency through selective processing

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If time-frequency transformation is performed and multiple subbands are processed, then phase information precision is improved, but device complexity increases

Engineering Contradiction:
Improvephase information precisionVSAvoidencoding complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies partial action by performing time-frequency transformation and IPD calculation only on selected subbands rather than processing all subbands uniformly. This reduces the overall computational complexity and device resource requirements while maintaining high phase information precision where it matters most

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentEP4390920B1Inter-channel phase difference parameter encoding method and apparatus
Publication Date: 2025.12.31 HUAWEI TECH CO LTD
  • EP4390920B1 patent drawingFigure 1~3
  • EP4390920B1 patent drawingFigure 4~5
  • EP4390920B1 patent drawingFigure 6

AI summary

This application discloses an inter-channel phase difference parameter encoding method, including: obtaining a reference parameter used to determine an inter-channel phase difference IPD parameter encoding scheme of a current frame of a multi-channel signal; determining the IPD parameter encoding scheme of the current frame based on the reference parameter, where the determined IPD parameter encoding scheme of the current frame is one of at least two preset IPD parameter encoding schemes; and processing an IPD parameter of the current frame based on the determined IPD parameter encoding scheme of the current frame. The technical solutions provided in this application can improve encoding quality of the multi-channel signal.