[music-dsp] Wavelet based real-time audio processing

[Matt Avent]

Tried to post this earlier but...?

I have recently spent some time implementing a DWT/IDWT system for
research purposes. Echoing below, perfect reconstruction does rely on
(a) you getting your sub-band delays right (an issue in frame based real
time), (b) you not altering any coefficients. Someone else said recently
that the DWT is useful for analysis purposes but not really for
synthesis. I would agree with this in a high fidelity sense. You can't
use a DWT system as a hi-fi graphic equaliser because of the aliasing,
however, I still think there are plenty of creative uses for it. In fact
the aliasing caused by altering the gain values of the sub-bands gives
quite musically pleasing results imo, probably due to the logarithmic
nature of the systems band structure. I'm investigating....


>Problem is that implementations of wavelet decomposition 
>involve multi-rate filters and the reconstruction relies on 
>alias cancellation.  If you change the coeficients before 
>reconstruction, the aliasing is not cancelled.
>
>
>Bob
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