You can get an array of magnitudes from an audio signal using the pvsanal and pvs2tab opcodes, example:

<CsoundSynthesizer>

<CsInstruments>

nchnls = 2

0dbfs = 1

ksmps = 256

sr = 44100

opcode AudioToPolar, k[]k[], aii

  aInput, iFrameSize, iHopSize xin

  kmags[] init iFrameSize/2 + 1

  kfreqs[] init iFrameSize/2 + 1

  fsig   pvsanal aInput, iFrameSize, iHopSize, iFrameSize, 1

  kframe  pvs2tab kmags, kfreqs, fsig

  xout kmags, kfreqs

endop

opcode Sine, a, kk

  kAmplitude, kFrequency xin

  aOut oscil kAmplitude, kFrequency, ftgen(0, 0, 2^10, 10, 1)

  xout aOut

endop

gaOut init 0

instr 1

    iFrameSize = 1024

    iHopSize = 256

    aOut Sine 0.4, 440

    kmagnitudes[], kfrequencies[] AudioToPolar aOut, iFrameSize, iHopSize

    printk2 kmagnitudes[5]

endin

</CsInstruments>

<CsScore>

i1 0 2

</CsScore>

</CsoundSynthesizer>

The kmagnitudes array will contain 513 magnitude values for each frame of the audio signal.

Hope that helps,

Ed

On 8 Aug 2017, at 14:02, Roger Kelly <loraxman@gmail.com> wrote:

I want to try to split an input signal of sine waves into their various partials.

Basically if the input contains 440HZ and 880HZ I want to be able to generate the midi note(s) for these.

I saw spectrum can a "wsig" of the DFT, but I don't see an opcode other than "spectdisp" that can give me access to the various bins and their magnitudes.

Any ideas on how to get to those frequency separations produced by "spectrum"? 

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Aug 8 2017, Roger Kelly has written:

I want to try to split an input signal of sine waves into their various
partials.

Hi Roger,
is there any particular need to use the spectrum opcode?
Otherwise the PVS family of opcodes allows you access and methods for
manipulation. If the supplied opcodes from the streamable real-time
phase vocoding opcodes - aka PVS - won't do, you have pvsftw and pvsftr
which will write both frequencies and related amplitudes into two tables
and can read them back into an f-rate signal.
...

Best wishes,

Jeanette

--------
* website: http://juliencoder.de - for summer is a state of sound
* SoundCloud: https://soundcloud.com/jeanette_c

And I love the way with just one whisper
You tell me everything <3
(Britney Spears)

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Aug 8 2017, Roger Kelly has written:

I want to try to split an input signal of sine waves into their various
partials.

Hi Roger,
is there any particular need to use the spectrum opcode?
Otherwise the PVS family of opcodes allows you access and methods for
manipulation. If the supplied opcodes from the streamable real-time
phase vocoding opcodes - aka PVS - won't do, you have pvsftw and pvsftr
which will write both frequencies and related amplitudes into two tables
and can read them back into an f-rate signal.
...

Best wishes,

Jeanette

--------
* website: http://juliencoder.de - for summer is a state of sound
* SoundCloud: https://soundcloud.com/jeanette_c

And I love the way with just one whisper
You tell me everything <3
(Britney Spears)

Csound mailing list
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Aug 10 2017, Roger Kelly has written:

So my attempt at using pvsanal is only giving me the same results for
amplitude as frequency.  What am I doing wrong here?

Two things: pvsftw returns the kflag, which is set to one, when a new
FFT-window has been analysed. That doesn't happen every k-cycle. So the
whole loop code should be inside an if-statement:
if kflag == 1 then
; loop stuff
endif

Second: for the loop you use all i-rate variables: i_index, i_value,
i_value2,... That means they can only be assigned once at i-time. Make
them k-rate: kindex, kvalue, kvalue2,...

Two minor points: you don't need to use the ftlen, you know the length
of the function. Secondly, with an FFT-size of 512, you get 256 bins or
maybe 257.

HTH.

Best wishes,

Jeanette

--------
* website: http://juliencoder.de - for summer is a state of sound
* SoundCloud: https://soundcloud.com/jeanette_c

Make all the clouds disappear
Put all your fears to rest <3

(Britney Spears)

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Aug 10 2017, Roger Kelly has written:
...

kflag pvsftw fftin,ifn,ifq ; export amps to table,



kndx init 0

kndx = 0 ; init only works once per instrument call

kncr=1

No need for kncr, loop_lt will solve that, at any rate this is a
constant, unless you plan to do interesting things.

kmax=256

That can be imax, it's a constant based on the i-rate FFT size.

isize = ftlen(ifq)

No need for isize, you have imax

if kflag == 1 then

loop_start:

   kvalue tablekt kndx, ifq

You can use table or even tab, no need for interpolation, you want the
absolute values at direct indces:
kvalue tab kndx, ifq ;, 0
I believe the reading mode is 0 by default

   kvalue2 tablekt kndx, ifn

Same here for tab

   if kvalue2 > 0.0 && kvalue > 00.0 then

You don't really need to check the frequency value, only one bin will
potentially contain a frequency of 0Hz

      printks "freq %d:\t%f\n",.001, kndx, kvalue

I usually go for something like:
printks "freq %d:\t%f\n", 1/sr, kndx, kvalue
You reach this statement only when analysis data from the FFT is
available. Lower rates can be helpful if you don't need every FFT frame.

      printks "amp  %d:\t%f\n",.001, kndx, kvalue2

   endif

Replace the lines below with:
loop_lt kndx, 1, imax, loop_start

   kndx  =  kndx + 1
   printks "kndx %d\n", .1,kndx

   printks "kmax %d\n", .1,kmax

   if (kndx < kmax) kgoto loop_start

...
>From here on everything can stay in place.

Best wishes,

Jeanette

--------
* website: http://juliencoder.de - for summer is a state of sound
* SoundCloud: https://soundcloud.com/jeanette_c

Make all the clouds disappear
Put all your fears to rest <3
(Britney Spears)

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