Quadrature mirror filter

About: Quadrature mirror filter is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 28900 citations.

On bit allocation strategies for paraunitary subband coders

Abstract: Quadrature mirror filters have been employed to decompose a signal into subbands. The signals in each subband are quantized before transmission. The authors derive conditions on the individual quantizer error variances so as to minimize the overall reconstruction error variance. The present results hold for filter banks having paraunitary polyphase matrices. Under the assumption that the total number of bits over all channels is fixed, it is shown that their distribution which minimizes the reconstruction error variance is the one that makes the individual quantizer variances equal. This analysis is extended to tree-structured filter banks, such as those used for generating orthonormal wavelets. In this case, it is shown that the quantizer error variance in a particular branch should be proportional to the corresponding decimation factor. >

Global optimization design of QMF filter banks

Abstract: In this paper, we present a new global optimisation method for designing QMF (quadrature mirror filters) filter banks. We formulate the design problem as a nonlinear constrained optimization problem, using the reconstruction error as the objective, and the stopband ripple, stopband energy, pass-band ripple, pass-band energy and transition bandwidth as constraints. This formulation allows us to search for solutions that improves with respect to the objective, and that performs better than or equal to the best existing designs with respect to the constrained measures. We present NOVEL, a global optimisation method we have developed for solving nonlinear continuous constrained optimisation problems, and apply it to find improved designs. We also show that relaxing the constraints on transition bandwidth and stopband energy will lead to significant improvements in the other performance measures.

Design and VLSI implementation of QMF banks

Abstract: The authors consider the design of multirate filterbanks for applications such as subband coding with IIR QMF (quadrature mirror filter) pairs. These offer reduced complexity and low latency at the expense of the loss of exact linear phase. In particular, consideration is given to the use of all-pass sections where linear phase is approximately achieved by being part of the objective in numerical optimisation experiments. This approach compares favourably with previous IIR based approaches. Finite wordlength design using simulated annealing shows that low coefficient wordlength may be used. This leads to efficient realisations with three-port adaptors. Using pipelining implementation, a flexible VLSI architecture is designed that can be used for a variety of subband decompositions. Layout and simulation of the design have been performed.

Design of 2-D Perfect Reconstruction Diamond-Shaped and Fan-Shaped FIR Filter Banks

Abstract: The paper gives a design method of two-channel FIR diamond-shaped and fan-shaped filter banks, which are the important part of directional filter banks. Firstly, we make an analysis of 2-D two-channel filter banks where the perfect reconstruction condition is derived. On this basis, the 2-D maximally flat filter is adopted to be the mapping filter and the 1- D two-channel filter bank is constructed to satisfying the perfect reconstruction condition. Afterwards the 1-D two-channel filter bank is mapped into the 2-D diamond-shaped filter bank using the method of variable substitution. Finally the 2-D fan-shaped filter bank is obtained by modulating the diamond-shaped filter bank.

Building an efficient mobile video streaming service

Abstract: Streaming video transmission is one of the most important new services in mobile networks. The existing image and video processing solutions are non-effective when using for mobile content delivery and can be optimized to increase the limited radio channel capacity and to improve the quality of reconstructed picture for the end-user. This can be achieved by using new modern signal processing algorithms of wavelets theory. The main idea is to analyze the whole signal by using special quadrature mirror filters and to perform a recursive decomposition of the signal to several frequency bands. The resulted coefficients are being processed by special algorithm to remove the redundancy.