dcblock

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

The result can be viewed in a graphical audio editor program like audacity. audacity is available for Linux, Windows, and the MacOS and may be downloaded from http://audacity.sourceforge.net.

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

Example of the dcblock opcode.
<CsoundSynthesizer>
<CsOptions>
; Select audio/midi flags here according to platform
-odac     ;;;RT audio out
;-iadc    ;;;uncomment -iadc if RT audio input is needed too
; For Non-realtime ouput leave only the line below:
;-o dcblock.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 32
nchnls = 2

instr 1 ;add DC to "drumsMlp.wav"

asig soundin "drumsMlp.wav"
asig = asig+5000        ;adds DC of 5000
     outs asig, asig
endin

instr 2 ;dcblock audio

asig soundin "drumsMlp.wav"
asig = asig+5000        ;adds DC
adc  dcblock asig       ;remove DC again
     outs adc, adc

endin

</CsInstruments>
<CsScore>

i 1 0 2
i 2 2 2
e

</CsScore>
</CsoundSynthesizer>

Credits

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

New in Csound version 3.49

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