Multi-window fast convolution processing

According to an aspect, there is provided a waveform processing device. Said waveform processing device comprises means for performing the following. Upon receiving one or more input signals, each of which corresponds to a different subband, the waveform processing device segments each of the one or more input signals to a subband-specific set of parallel signal blocks. Then, the waveform processing device filters each subband-specific set by applying at least a first time window function, a transform-plane window function and a second time window function in this order. Finally, the waveform processing device concatenates filtered signals to an output signal.