downsamp — Modify a signal by down-sampling.
iwlen (optional) -- window length in samples over which the audio signal is averaged to determine a downsampled value. Maximum length is ksmps; 0 and 1 imply no window averaging. The default value is 0.
downsamp converts an audio signal to a control signal by downsampling. It produces one kval for each audio control period. The optional window invokes a simple averaging process to suppress foldover.
Here is an example of the downsamp opcode. It uses the file downsamp.csd.
Example 114. Example of the downsamp 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 downsamp.wav -W ;;; for file output any platform
</CsOptions>
<CsInstruments>
; Initialize the global variables.
sr = 44100
kr = 4410
ksmps = 10
nchnls = 1
; Instrument #1.
instr 1
; Create a noise signal at a-rate.
anoise noise 20000, 0.2
; Downsample the noise signal to k-rate.
knoise downsamp anoise
; Use the noise signal at k-rate.
a1 oscil 30000, knoise, 1
out anoise
endin
</CsInstruments>
<CsScore>
; Table #1, a sine wave.
f 1 0 16384 10 1
; Play Instrument #1 for one second.
i 1 0 1
e
</CsScore>
</CsoundSynthesizer>