Audio Codec Mode Selection Using Estimated Quality Measures
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Solution Overview
Problem
Existing switched audio coders face complexity challenges in selecting between different encoding algorithms for audio signals, with open-loop mode selection performing worse than closed-loop methods but reducing complexity, and existing solutions rely on feature calculation and statistical evaluation which are not as effective.
Innovation Solution
An apparatus and method that estimate quality measures for each encoding algorithm without actual encoding and decoding, using segmental SNR in the weighted signal domain to select the best algorithm based on comparison, similar to closed-loop mode selection but with reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closed-loop mode selection is used to select between encoding algorithms, then codec quality is improved, but computational complexity increases significantly
Solution Approach 1:
The patent applies preliminary action by estimating quality measures (segmental SNR) for different encoding algorithms before actual encoding occurs. The estimator computes quality metrics in advance using simplified models, allowing the mode selector to make informed decisions without performing complete encoding/decoding cycles for each candidate algorithm, thus reducing computational complexity while maintaining quality assessment accuracy.
Solution Approach 2:
The patent introduces an intermediary quality estimator that mediates between the encoding algorithms and the mode selection process. This estimator acts as a surrogate that predicts encoding quality without requiring full encoding operations, using segmental SNR calculations on weighted signal domains to provide reliable quality metrics at lower computational cost.
2Device complexity
If open-loop mode selection is used to reduce complexity, then computational complexity is reduced, but codec quality deteriorates
Solution Approach 1:
The patent replaces the mechanical system of actual encoding/decoding operations with a computational model that estimates quality measures. Instead of physically executing the encoding process to assess quality, the system uses mathematical estimators that compute segmental SNR in weighted signal domains, substituting complex mechanical encoding operations with lighter computational calculations.
Solution Approach 2:
The patent changes parameters by working in the weighted signal domain rather than the original audio domain. By applying weighting functions to the signal before estimation, the system transforms the problem space to make quality assessment more efficient and accurate, allowing reliable quality prediction with reduced computational effort compared to unweighted full-encoding approaches.
Data Source
AI summary
An apparatus for selecting one of a first encoding algorithm having a first characteristic and a second encoding algorithm having a second characteristic for encoding a portion of an audio signal to obtain an encoded version of the portion of the audio signal has a first estimator for estimating a first quality measure for the portion of the audio signal, which is associated with the first encoding algorithm, without actually encoding and decoding the portion of the audio signal using the first encoding algorithm. A second estimator is provided for estimating a second quality measure for the portion of the audio signal, which is associated with the second encoding algorithm, without actually encoding and decoding the portion of the audio signal using the second encoding algorithm. The apparatus has a controller for selecting the first or second encoding algorithms based on a comparison between the first and second quality measures.


