Transform Coefficient Extraction With Adaptive Threshold Encoding
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Solution Overview
Problem
Existing methods for extracting transform coefficients in extension bands require a large amount of calculation, which is inefficient, especially when the number of coefficients is small, leading to reduced accuracy and increased computational load.
Innovation Solution
A coding apparatus that calculates a threshold based on statistics for each extension-band subband, extracts representative transform coefficients with amplitudes above the threshold, and updates the threshold adaptively to ensure a predetermined number of coefficients are extracted efficiently, reducing the number of loops and calculation required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all transform coefficients in extension-band subbands are used for correlation calculation, then measurement precision is improved, but the amount of calculation increases significantly
Solution Approach 1:
The patent extracts only the necessary subset of transform coefficients (those with large amplitudes) from the extension-band subbands for correlation calculation, rather than using all coefficients. This extraction is performed by comparing coefficient amplitudes against a threshold value, thereby reducing the calculation load while preserving the essential information needed for accurate correlation measurement.
Solution Approach 2:
The patent applies different processing strategies to different portions of the transform coefficients based on their local characteristics. Specifically, coefficients with large amplitudes are selected for correlation calculation while those with small amplitudes are excluded. This local differentiation ensures that the most significant coefficients contribute to the correlation measurement, maintaining precision while improving efficiency.
2Productivity
If a threshold is set too high to reduce the number of transform coefficients, then the amount of calculation is reduced, but the number of extracted coefficients becomes insufficient
Solution Approach 1:
The patent employs a dynamic threshold adjustment mechanism where the threshold value is not fixed but is adaptively modified based on the number of coefficients extracted in each iteration. When the extracted coefficient count falls below a predetermined threshold, the system automatically lowers the threshold to include more coefficients, ensuring that the final set meets the minimum quantity requirement while still maintaining calculation efficiency.
Solution Approach 2:
The system implements a feedback loop that monitors the number of extracted coefficients and uses this information to adjust the threshold for subsequent extraction iterations. This feedback mechanism ensures that the extraction process adapts to maintain an adequate number of coefficients, preventing the threshold from being set too high and causing insufficient extraction.
3Productivity
If transform coefficients are extracted using statistical thresholding, then the amount of calculation is reduced, but the variation in extracted coefficients increases
Solution Approach 1:
The patent performs preliminary sorting of transform coefficients by amplitude before applying threshold-based extraction. This preliminary arrangement of coefficients in descending order of amplitude ensures that the most significant coefficients are considered first, providing a stable and consistent basis for extraction that reduces variation in the selected coefficient sets across different iterations or signals.
Data Source
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AI summary
Provided is an encoding apparatus. A threshold value calculating unit (32) calculates a threshold value from a statistical amount of conversion factors of an extended band. A representative conversion factor extracting unit (33) uses the calculated threshold value to extract conversion factors having large amplitudes. If the number of extracted conversion factors does not reach a specified number, the threshold value calculating unit (32) determines, in accordance with a lacking number of conversion factors, an amount by which the threshold value should be lowered, and modifies the threshold value accordingly. The representative conversion factor extracting unit (33) uses the threshold value, which has been modified, to extract conversion factors. Such threshold value modification by the threshold value difference calculating unit (32) and such conversion factor extraction by the representative conversion factor extracting unit (33) are repeated until the number of extracted conversion factors reaches the specified number.