mags — Obtains the magnitudes of a complex-number array
This opcode returns the magnitudes of a complex-number array (in rfft format), as a real-valued array with half the size of its input plus one. The magnitude for the Nyquist frequency are kept in the last position of the array.
kout[] -- output array containing the magnitudes (size = input_size/2 + 1). It will be created if it does not exist.
kin[] -- input array containing the complex-valued real-imaginary input.
Here is an example of the mags opcode. It uses the file mags.csd.
Example 567. Example of the mags opcode.
See the sections Real-time Audio and Command Line Flags for more information on using command line flags.
<CsoundSynthesizer> <CsOptions> -d -o dac </CsOptions> <CsInstruments> /* ksmps needs to be an integer div of hopsize */ ksmps = 64 0dbfs=1 nchnls=2 opcode PVA,k[]k[]k,aii asig,isize,ihop xin iolaps init isize/ihop kcnt init 0 krow init 1 kIn[] init isize kOlph[] init isize/2 + 1 ifac = (sr/(ihop*2*$M_PI)) iscal = (2*$M_PI*ihop/isize) kfl = 0 kIn shiftin asig if kcnt == ihop then kWin[] window kIn,krow*ihop kSpec[] rfft kWin kMags[] mags kSpec kPha[] phs kSpec kDelta[] = kPha - kOlph kOlph = kPha kk = 0 kDelta unwrap kDelta while kk < isize/2 do kPha[kk] = (kDelta[kk] + kk*iscal)*ifac kk += 1 od krow = (krow+1)%iolaps kcnt = 0 kfl = 1 endif xout kMags,kPha,kfl kcnt += ksmps endop opcode PVS,a,k[]k[]kii kMags[],kFr[],kfl,isize,ihop xin iolaps init isize/ihop ifac = ihop*2*$M_PI/sr; iscal = sr/isize krow init 0 kOla[] init isize kOut[][] init iolaps,isize kPhs[] init isize/2+1 if kfl == 1 then kk = 0 while kk < isize/2 do kFr[kk] = (kFr[kk] - kk*iscal)*ifac kk += 1 od kPhs = kFr + kPhs kSpec[] pol2rect kMags,kPhs kRow[] rifft kSpec kWin[] window kRow, krow*ihop kOut setrow kWin, krow kOla = 0 kk = 0 until kk == iolaps do kRow getrow kOut, kk kOla = kOla + kRow kk += 1 od krow = (krow+1)%iolaps endif xout shiftout(kOla)/iolaps endop instr 1 ihopsize = 256 ; hopsize ifftsize = 2048 ; FFT size kFreqsOut[] init ifftsize/2+1 ; synthesis freqs kMagsOut[] init ifftsize/2+1 ; synthesis mags a1 diskin2 "fox.wav",1,0,1 kMags[],kFreqs[],kflg PVA a1,ifftsize,ihopsize if kflg == 1 then ki = 0 kMagsOut = 0 kFreqsOut = 0 iscal = 1.5 until ki == ifftsize/2 do if ki*iscal < ifftsize/2 then kFreqsOut[ki*iscal] = kFreqs[ki]*iscal kMagsOut[ki*iscal] = kMags[ki] endif ki += 1 od endif a2 PVS kMagsOut,kFreqsOut,kflg,ifftsize,ihopsize a1 delay a1, (ifftsize+ihopsize)/sr outs a1, a2 endin </CsInstruments> <CsScore> i1 0 10 </CsScore> </CsoundSynthesizer>