pvsdemix — Spectral azimuth-based de-mixing of stereo sources.
Spectral azimuth-based de-mixing of stereo sources, with a reverse-panning result. This opcode implements the Azimuth Discrimination and Resynthesis (ADRess) algorithm, developed by Dan Barry (Barry et Al. "Sound Source Separation Azimuth Discrimination and Resynthesis". DAFx'04, Univ. of Napoli). The source separation, or de-mixing, is controlled by two parameters: an azimuth position (kpos) and a subspace width (kwidth). The first one is used to locate the spectral peaks of individual sources on a stereo mix, whereas the second widens the 'search space', including/exclufing the peaks around kpos. These two parameters can be used interactively to extract source sounds from a stereo mix. The algorithm is particularly successful with studio recordings where individual instruments occupy individual panning positions; it is, in fact, a reverse-panning algorithm.
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It is unsafe to use the same f-variable for both input and output of pvs opcodes. Using the same one might lead to undefined behavior on some opcodes. Use a different one on the left and right sides of the opcode. |
fsig -- output pv stream
fleft -- left channel input pv stream.
fright -- right channel pv stream.
kpos -- the azimuth target centre position, which will be de-mixed, from left to right (-1 <= kpos <= 1). This is the reverse pan-pot control.
kwidth -- the azimuth subspace width, which will determine the number of points around kpos which will be used in the de-mixing process. (1 <= kwidth <= ipoints)
ipoints -- total number of discrete points, which will divide each pan side of the stereo image. This ultimately affects the resolution of the process.
The example below takes a stereo input and passes through a de-mixing process revealing a source located at ipos +/- iwidth points. These parameters can be controlled in realtime (e.g. using FLTK widgets or MIDI) for an interactive search of sound sources.
Example 686. Example
ifftsize = 1024 iwtype = 1 /* cleaner with hanning window */ ipos = -0.8 /* to the left of the stereo image */ iwidth = 20 /* use peaks of 20 points around it */ al,ar soundin "sinput.wav" flc pvsanal al, ifftsize, ifftsize/4, ifftsize, iwtype frc pvsanal ar, ifftsize, ifftsize/4, ifftsize, iwtype fdm pvsdemix flc, frc, kpos, kwidth, 100 adm pvsynth fdm outs adm, adm