I'm trying to use arrays to modify pvs amp data,
but it seems I'm not getting what I expect.
Could I be doing something wrong, or is something not working as it should?

In the example below, I (expect to) find the bin with the strongest
amplitude and reduce that amplitude by a factor, then do the same
operation again (100 times).
I resynthesize the unmodified and the modified signal to the right and
left channels respectively.

If I comment out the line
    kArr2[kMaxIndx]    = kMax*0.01
then I would expect the unmodified and "modified" signals to be the
same but they are not.







sr = 44100
ksmps = 128
nchnls = 2
0dbfs=1

    giSine        ftgen    0, 0, 65537, 10, 1

; pvs ftables
    gifftsize     = 512
    giFftTabSize    = (gifftsize / 2) + 1
    gifna         ftgen   0 ,0 ,giFftTabSize, 7, 1, giFftTabSize, 1
; make ftable for pvs analysis
    gifnf         ftgen   0 ,0 ,giFftTabSize, 7, 1, giFftTabSize, 1
; make ftable for pvs analysis
    gifnaMod         ftgen   0 ,0 ,giFftTabSize, 7, 1, giFftTabSize, 1
  ; make ftable for modified pvs data

    instr 99

    ; test tone
    kscal        line 1, p3, 2
    a1        oscili 0.1, 220*kscal, giSine
    a2        oscili 0.2, 330*kscal, giSine
    a3        oscili 0.1, 440*kscal, giSine
    a4        oscili 0.5, 1550*kscal, giSine
    ain        = (a1+a2+a3+a4) * 0.1

    iwtype         = 0
    fsin         pvsanal    ain, gifftsize, gifftsize/4, gifftsize, iwtype
    kflag       pvsftw    fsin,gifna,gifnf              ; export  amps
 and freqs to table,

    ; copy pvs data from table to array
    ; modify amplitude of single bin
    ; repeat the above N number of times
    ; transfer array to pvs data

if kflag > 0 then
    ; copy pvs data from table to array
    kArr2[]      init    giFftTabSize-1
                copyf2array kArr2, gifna

    kcount         = 0
if kcount < 100 then
    kMax ,kMaxIndx     maxarray kArr2
    kArr2[kMaxIndx]    = kMax*0.01
    kcount = kcount + 1
endif
                copya2ftab kArr2, gifnaMod
endif

    ; resynth unmodified
    aout1        pvsynth    fsin
    ; modify and resynth
            pvsftr fsin, gifnaMod, gifnf
    aout        pvsynth    fsin

            outch 1, aout, 2, aout1

    endin



i99    0    10
e






-- 

Oeyvind Brandtsegg
Professor of Music Technology
NTNU
7491 Trondheim
Norway
Cell: +47 92 203 205

http://flyndresang.no/
http://www.partikkelaudio.com/
http://soundcloud.com/brandtsegg
http://soundcloud.com/t-emp