dcblock
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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

    ares dcblock ain [, igain]

## Initialization

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

## Performance

ain -- audio signal input

| Note
The new dcblock2 opcode is an improved method of removing DC from an audio signal.

## Examples

Here is an example of the dcblock opcode. It uses the file dcblock.csd, and beats.wav.

Example 112. Example of the dcblock opcode.

See the sections Real-time Audio and Command Line Flags for more information on using command line flags.

    <CsoundSynthesizer>
    <CsOptions>
    ; Select audio/midi flags here according to platform
    ; Audio out   Audio in    No messages
    -odac           -iadc     -d     ;;;RT audio I/O
    ; For Non-realtime ouput leave only the line below:
    ; -o dcblock.wav -W ;;; for file output any platform
    </CsOptions>
    <CsInstruments>

    ; 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

    </CsInstruments>
    <CsScore>

    ; Play Instrument #1 for 2 seconds.
    i 1 0 2
    ; Play Instrument #2 for 2 seconds.
    i 2 2 2
    e

    </CsScore>
    </CsoundSynthesizer>

## See also

dcblock2

## 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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