Four-band linear-phase orthogonal spatial filter bank for subband video coding
In wavelet-based scalable video coding schemes, temporal interframe redundancy is exploited by applying a temporal wavelet transform along the motion trajectories. A spatial decomposition of the temporal subbands is further performed to take advantage of the spatial redundancy of the filtered frames. However, most of the t+2D video codecs do not take into account the very different spatial characteristics of the temporal subband frames and use indifferently the same spatial 9/7 biorthogonal transform to decompose them. In this paper, we present a spatial transform based on a four-band filter bank, whose frequency selectivity properties are shown to be more suited to represent detail frames. We give the analytical form of a linear-phase, orthogonal and regular four-band filter bank and we show by experimental results conducted on video sequences that significant improvements in terms of PSNR can be obtained using the proposed filter bank to decompose the detail frames.