Filter Banks For Subband Coding Research Articles

Adaptive-Differential-Evolution-Based Design of Two-Channel Quadrature Mirror Filter Banks for Sub-Band Coding and Data Transmission

This paper proposes an improved and adaptive variant of the differential evolution algorithm for the design of two-channel quadrature mirror filters with linear phase characteristics. To match the ideal system response characteristics, the algorithm is employed to optimize the values of the filter bank coefficients. The filter response is optimized in both passband and stopband. The overall filter bank response aims at minimizing objectives like reconstruction error, mean square error in passband, and mean square error in stopband. Effective designing can be achieved by efficiently minimizing the objective function. The proposed algorithm is able to perform better than the other existing design methods. Five different design examples are presented to validate the effectiveness of the proposed approach over other conventional design techniques, as well as state-of-the-art evolutionary algorithms found in the literature.

Multidimensional causal, stable, perfect reconstruction filter banks

Following our earlier one-dimensional (1-D) work, we show that it is possible to have a large family of biorthogonal perfect reconstruction multidimensional (n-D) subband coding filter banks, which are causal and IIR both at the analysis and at the synthesis ends. While the need for perfect reconstruction IIR filter banks are more apparent for multidimensional signals than for 1-D signals, lack of design techniques have made it impossible to use such schemes. We argue that such filter banks, including their multichannel counterparts, should not only exist in a large variety, but we also indicate a number of tools potentially useful in their design. Specifically, a complete parameterization of such filters leading to design methods in 2-D are given. Parameterizations in frequency domain terms as well as in terms of state space descriptions of filters are provided. These latter techniques have potential for better numerical implementation. The development is valid for two-band as well as for multiband subband coding schemes. Examples of bi-orthogonal version of continuous multidimensional wavelets generated by these iterated filter banks, that have not been previously constructed, are worked out.

Optimal construction of filter banks for subband coding of quantised signals

A new general method is presented for the analysis of the effects of quantisation and transmission noise in subband filter bank coders. Using general statistical noise characterisation, the filter banks are obtained, which are optimal in the sense of minimising the variance of the difference of the reconstructed signal from the original. It is shown that these are not identical to those achieving perfect reconstruction in lossless coding. A general method is described for the optimal selection of the synthesis filters if the analysis filters and quantisers are given. Assumming the use of these optimal synthesis filters, a method is developed for the determination of the optimal analysis filters and the optimal bit allocation to the subbands. The effects of quantisation on perfect reconstruction filter banks are analysed next, and an explicit expression is determined for the quantiser noise-to-signal ratio for such banks. Given arbitrary quantisers, the analysis filters which are optimal in the sense of minimising the output noise power are obtained. Finally, the jointly optimal selection is determined for the analysis filters and the bit allocations of the subbands. It is seen that this selection is identical to that determined for the theoretically optimal filter banks.

VLSI architectures of filterbanks for subband coding of hdtv signals

VLSI architectures of filterbanks necessary for an HDTV subband codec have been investigated. Different techniques have been combined in order to achieve a compact realization. The application of special QMF structures results in a further reduction of hardware expense. High clocking rates are handled using two dimensional polyphase filterbanks in combination with pipelining and parallel processing. An architecture suitable for one-chip implementation of a 10 x 14 tap QM filterbank has been developed.