Audio Quality Assessment Sampling Rate Error Coefficient
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Solution Overview
Problem
Existing objective methods for predicting the subjective quality of audio signals in telecommunications systems are affected by sampling errors, particularly when there are slight differences in sampling rates between reference and degraded signals, leading to inaccuracies in Mean Opinion Score (MOS) predictions, especially in systems with analogue stages or time-warping algorithms.
Innovation Solution
The method involves detecting periodicity changes between transmitted and received signals to determine sampling errors, matching sample rates by re-sampling, and generating a sampling rate error coefficient using periodicity measures from both signals, which can then be used to resample and improve quality assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If intrusive quality assessment systems compare reference and degraded signals, then automated quality prediction is achieved, but sampling rate differences cause artificial MOS degradation
Solution Approach 1:
The patent applies preliminary action by detecting sampling rate differences between reference and degraded signals before performing the quality comparison. The system calculates a sampling rate error coefficient and resamples one signal to match the other's rate, thereby preventing spectral misalignment from occurring during the assessment process.
Solution Approach 2:
The patent changes the sampling rate parameter of one signal to match the other signal's sampling rate. By adjusting this physical parameter before comparison, the system eliminates spectral misalignment and prevents artificial MOS degradation while maintaining automated assessment capabilities.
2Measurement precision
If spectral content alignment is maintained between reference and degraded signals, then accurate MOS prediction is achieved, but this requires precise sampling rate matching
Solution Approach 1:
The patent applies self-service by having the system automatically detect sampling rate differences, calculate the error coefficient, and perform resampling without external intervention. The quality assessment system itself identifies and corrects its own sampling rate mismatch problem, simplifying the overall process despite the additional steps required for alignment.
3Measurement precision
If resampling is performed to correct sampling rate errors, then spectral alignment is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent applies partial action by performing resampling only when a sampling rate difference is detected, rather than always resampling. The system calculates the sampling rate error coefficient and only applies the correction when necessary, thereby maintaining spectral alignment accuracy while minimizing unnecessary processing time and computational overhead.
Data Source
AI summary
This invention relates to generation of a sample error coefficient suitable for use in an audio signal quality assessment system. The invention provides a method of determining a sample error coefficient between a first signal and a similar second signal comprising the steps of: determining a first periodicity measure from the first signal; determining a second periodicity measure from the second signal; generating a ratio in dependence upon said first periodicity measure and said second periodicity measure; and determining a sampling rate error coefficient in dependence upon said ratio.