Quadrature Mirror Filtering with Modulo Addressing for Lower Complexity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
QMF-based sub-band coding requires a significant amount of calculation to achieve its effectiveness, leading to resource inefficiencies in audio coding methods.
Innovation Solution
A method and apparatus that reduce the complexity of QMF filtering by circulating sample recording positions, determining sample extraction positions based on time slots, and selecting filter coefficients using modulo operations, allowing for efficient bit allocation based on human hearing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If QMF-based sub-band coding is used to achieve effective audio compression, then audio coding effectiveness is improved, but calculation complexity increases significantly
Solution Approach 1:
The audio signal is divided into multiple frequency sub-bands using QMF banks, allowing independent processing of each sub-band. This segmentation enables selective bit allocation to different frequency ranges based on human hearing sensitivity, improving coding efficiency while managing computational complexity through distributed processing
Solution Approach 2:
Different bit allocation strategies are applied to different frequency sub-bands according to local characteristics of human hearing sensitivity. Low-frequency sub-bands receive higher bit rates where human ears are most sensitive, while high-frequency sub-bands receive fewer bits, optimizing overall perceptual quality while reducing total calculation burden
2Adaptability or versatility
If more bits are allocated to high-frequency ranges, then frequency coverage is improved, but the number of encoded bits increases
Solution Approach 1:
The bit allocation parameter is dynamically changed based on frequency sub-band characteristics. By adjusting the number of bits allocated to each sub-band according to human hearing sensitivity curves, the system achieves efficient frequency coverage without unnecessarily increasing total bit rate, particularly by reducing bits in less sensitive high-frequency regions
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method of performing quadrature mirror filter (QMF) synthesis filtering includes recording new samples corresponding to a current time slot at positions of samples to be discarded in a first array that includes modulated QMF sub-band samples. The method further includes extracting samples from the first array to remove aliasing between adjacent sub-bands, determining filter coefficients corresponding to the extracted samples by using modulo operation, and synthesizing a time domain sample where aliasing is removed by using the extracted samples and the filter coefficients.