Reducing artefacts for short time spans

[johnmgithub]

The integer truncation of the index into the mother wavelet causes some artefacts for short time spans. Those can be reduced without performance penalty by generating the mother data at a multiple of size for sizes below some threshold and passing that multiple to the daughter wavelet multiplication to scale the step.

[fastlib]

Very nice comment. At what signal lengths did you experience artifacts?

[johnmgithub]

I noticed them at widths below a few k samples, but I apply some hill shading on my spectrograms so that makes them more visible than they would be on a flat spectrogram. I'm using a minimum length for the mother wavelet of 64k now, that eliminates them completely. I mainly use the spectrograms for looking at impulse responses, so I'm applying scale normalisation with those which might also make the artefacts more visible.