Audio Encoding of Weighted QMF Sub-Band Power for Clearer Decoding
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Solution Overview
Problem
In audio signal encoding, the power of the original signal is not accurately reproduced during decoding due to the mean value of power in high frequency scale factor bands being used, leading to diminished audio clarity and degraded quality.
Innovation Solution
An encoding device that divides the input signal into sub-bands, calculates sub-band power, weights higher power sub-bands more, and generates high frequency signals based on these calculations, while also using pseudo high frequency sub-band power estimates to improve signal reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mean value of power of each frequency band is used to represent the power of the scale factor band, then the encoding process is simple, but the power of the original signal cannot be reproduced accurately during decoding
Solution Approach 1:
The patent changes the parameter representation from simple mean value to a more sophisticated model that considers the relationship between low frequency and high frequency power. Specifically, it uses the power of low frequency scale factor bands and applies weighting coefficients to estimate high frequency power, thereby improving power reproduction accuracy while maintaining encoding efficiency.
Solution Approach 2:
The patent introduces an intermediary calculation process that uses low frequency power information as a mediator to estimate high frequency power. By using the power of low frequency scale factor bands and applying appropriate weighting, it creates an intermediate representation that bridges the gap between simple encoding and accurate power reproduction.
2Device complexity
If the mean value of power is used for high frequency scale factor bands, then the encoding complexity is reduced, but the audio clarity and quality are degraded
Solution Approach 1:
The patent modifies the power calculation parameters by introducing weighting coefficients that reflect the actual distribution of power across frequency bands. Instead of using a uniform mean value, it applies different weights to low frequency and high frequency components, thereby improving audio quality without significantly increasing encoding complexity.
Solution Approach 2:
The patent performs preliminary calculations of low frequency power and prepares weighting coefficients in advance during the encoding process. This preliminary action allows the decoder to reconstruct power values more accurately without adding complex real-time processing requirements, thus maintaining encoding simplicity while improving audio quality.
3Speed
If simple mean value calculation is used for sub-band power, then the processing speed is fast, but the reproduced power does not match the original signal
Solution Approach 1:
The patent changes the power calculation from a simple mean value to a weighted sum that incorporates low frequency power information and frequency-dependent weighting coefficients. This parameter change improves power reproduction fidelity while maintaining relatively fast processing speed by using efficient mathematical operations.
Solution Approach 2:
The patent performs preliminary computation of weighting coefficients and low frequency power values during encoding. This preliminary action enables the decoder to quickly reconstruct power values using pre-computed parameters, thereby maintaining fast processing speed while achieving accurate power reproduction that matches the original signal.
Data Source
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AI summary
The present technology relates to an encoding device and method, a decoding device and method, and a program, which enable improvement of audio quality. A QMF sub-band power calculation unit calculates power of a QMF sub-band signal of a high frequency QMF sub-band among a plurality of the QMF sub-bands constituting an input signal. A high frequency sub-band power calculation unit carries out an operation to weight more a QMF sub-band power having larger power as for a sub-band including a number of the high frequency QMF sub-bands to calculate high frequency sub-band power of the sub-band. The multiplexing circuit multiplexes high frequency encoded data and low frequency encoded data for outputting. The high frequency encoded data is selected based on the high frequency sub-band power and obtained by encoding information used for obtaining a high frequency component of the input signal by estimating, and the low frequency encoded data is obtained by encoding low frequency components of the input signal. The present technology can be applied to encoding devices.