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# dcblock

dcblock -- A DC blocking filter.

## Description

Implements the DC blocking filter

Y[i] = X[i] - X[i-1] + (igain * Y[i-1])

Based on work by Perry Cook.

## Syntax

ar dcblock ain [, igain]

## Initialization

igain -- the gain of the filter, which defaults to 0.99

## Performance

ain -- audio signal input

## Examples

Here is an example of the dcblock opcode. It uses the files dcblock.orc, dcblock.sco, and beats.wav.

Example 1. Example of the dcblock opcode.

    /* dcblock.orc */
    ; Initialize the global variables.
    sr = 44100
    kr = 4410
    ksmps = 10
    nchnls = 1

    ; Instrument #1 -- normal audio signal.
    instr 1
      asig soundin "beats.wav"
      out asig
    endin

    ; Instrument #2 -- dcblock-ed audio signal.
    instr 2
      asig soundin "beats.wav"

      igain = 0.75
      a1 dcblock asig, igain

      out a1
    endin
    /* dcblock.orc */

    /* dcblock.sco */
    ; Play Instrument #1 for 2 seconds.
    i 1 0 2
    ; Play Instrument #2 for 2 seconds.
    i 2 2 2
    e
    /* dcblock.sco */

## Credits

Author: John ffitch
University of Bath, Codemist Ltd.
Bath, UK

Example written by Kevin Conder.

New in Csound version 3.49

February 2003: Thanks to a note from Anders Andersson, corrected the formula.

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