FFT-based EQ.

in RTcmix/insts/jg/SPECTACLE2

quick syntax:

SPECTEQ2(outsk, insk, dur, AMP, fftsize, windowsize, WINDOWTABLE, overlap, EQTABLE[, MINFREQ, MAXFREQ, BYPASS, inputchan, PAN])

CAPITALIZED parameters are pfield-enabled for table or dynamic control (see the maketable or makeconnection scorefile commands). Parameters after the [bracket] are optional and default to 0 unless otherwise noted.

Param Field Parameter Units Dynamic Optional Notes
p0 output start time seconds no no  
p1 input start time seconds no no  
p2 duration seconds no no  
p3 amplitude multiplier relative multiplier of input signal yes no  
p4 FFT length samples, power of 2, no no usually 1024
p5 window length samples, power of 2 no no usually FFT length * 2
p6 window table reference to pfield table-handle yes no use zero for internally generated Hamming window
p7 overlap (FFT window overlap) positive power of 2: 1: no overlap, 2: hopsize=FFTlen/2, 4: hopsize=FFTlen/4, etc. no no 2 or 4 is usually fine; 1 is fluttery; higher overlaps use more CPU
p8 EQ table (i.e., amplitude scaling of each band) dB (use reference to pfield table-handle) yes no 0 dB means no change, +dB boost, -dB cut
p9 minimum frequency Hz yes yes default: 0 Hz
p10 maximum frequency Hz yes yes default: Nyquist
p11 bypass 0: bypass off, 1: bypass on yes yes default: 0
p12 input channel - no yes default: 0
p13 pan 0-1 stereo; 0.5 is middle yes yes default: 0

Parameters labled as Dynamic can receive dynamic updates from a table or real-time control source.

Author: John Gibson, 6/12/05

SPECTEQ2 is an evolution of the earlier SPECTEQ instrument. It can do very specific filtering jobs, operating directly on the FFT analysis of a signal spectrum.

Usage Notes

SPECTEQ2 is very similar in design to the SPECTACLE2 instrument. You may wish to consult the SPECTACLE2 Usage Notes for additional information.

As in SPECTACLE2, it is possible to update the EQ table (p8, “EQTABLE”) dynamically using the modtable(table, “draw”, …) scorefile command.

Output begins after a brief period of time during which internal buffers are filling. This time is the duration corresponding to the following number of sample frames: window length - (fft length / overlap).

Parameters p9 (“MINFREQ”) and p10 (“MAXFREQ”) operate in a similar way to the range parameters in SPECTACLE2.

SPECTEQ2 can produce either mono or stereo output.

There are no sample scorefiles.

See Also