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Signal Modifiers: Standard Filters

resony

  ar      resony    asig, kbf, kbw, inum, ksep[, isepmode, iscl, iskip]

Description

A bank of second-order bandpass filters, connected in parallel.

Initialization

inum – number of filters

isepmode – if isepmode = 0, the separation of center frequencies of each filter is generated logarithmically (using octave as unit of measure). If isepmode != 0, the separation of center frequencies of each filter is generated linearly (using Hertz). Default value is 0.

iscl – coded scaling factor for resonators. A value of 1 signifies a peak response factor of 1, i.e. all frequencies other than kcf are attenuated in accordance with the (normalized) response curve. A value of 2 raises the response factor so that its overall RMS value equals 1. (This intended equalization of input and output power assumes all frequencies are physically present; hence it is most applicable to white noise.) A zero value signifies no scaling of the signal, leaving that to some later adjustment (e.g. balance). The default value is 0.

iskip – initial disposition of internal data space. Since filtering incorporates a feedback loop of previous output, the initial status of the storage space used is significant. A zero value will clear the space; a non-zero value will allow previous information to remain. The default value is 0.

Performance

asig – audio input signal

kbf – base frequency, i.e. center frequency of lowest filter in Hz

kbw – bandwidth in Hz

ksep – separation of the center frequency of filters in octaves

resony is a bank of second-order bandpass filters, with k-rate variant frequency separation, base frequency and bandwidth, connected in parallel (i.e. the resulting signal is a mix of the output of each filter). The center frequency of each filter depends of kbf and ksep variables. The maximum number of filters is set to 100.

Example

In this example the global variable gk1 modifies kbf, gk2 modifies kbw, gk3 inum, gk4 ksep, and gk5 the main volume.

instr	1
  a1      soundin   "myfile.aif"
  a2      resony    a1, gk1, gk2, i(gk3), gk4, 2
          out       a2 * gk5
endin

Author

Gabriel Maldonado
Italy
1999
New in Csound version 3.56


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Signal Modifiers: Standard Filters