Spectral Blurring in MSP w/PVOC?


    Jul 27 2013 | 3:22 am
    I'm looking for a way to implement spectral blurring in real-time in Max. The caveat being that I need to only use MSP objects so this means no Jitter work ala Jean-Francois Charles' work on spectral processing (http://cycling74.com/toolbox/charles-spectral-tutorials/).
    I have read the Phase Vocoder tutorial
    (http://cycling74.com/2006/11/02/the-phase-vocoder-%E2%80%93-part-i/)
    in order to try and figure it out but have hit a brick wall in my understanding.
    My limited understanding of this effect comes from Trevor Wishart and Michael Norris.
    http://www.digital-music-archives.com/webdb2/application/Application.php?fwServerClass=ProductDetail&ProductCode=BKE0001#spectralmanipulation
    Any insights or examples would be much appreciated!

    • Jul 27 2013 | 8:56 pm
      From Wishart:
      We may average the spectral data in a each frequency-band channel over N time-windows (spectral blurring) thus reducing the amount of detail available for reconstructing the signal. This can be used to "wash out" the detail in a segmented signal and works especially effectively on spikey crackly signals (those with brief, bright peaks). We can do this and also reduce the number of partials (spectral trace & blur) and we may do either of these things in a time-variable manner so that the details of a sequence gradually become blurred or gradually emerge as distinct. (Sound example 3.25).
      You can do something like this via the vectral~ object. (the smearing via envelope following) Vectral~ is a vector-based envelope follower and has several different modes.
      Looking at the Michael Norris page, it looks like he's doing something more like sampling a spectral frame every n frames, then interpolating between that and the next one. The part of the implementation that's not clear is what you do in terms of overlapping frames.