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lpshold

Generate control signal consisting of held segments.

The segments are delimited by two or more specified points. The entire envelope is looped at kfreq rate. Each parameter can be varied at k-rate.

Syntax

ksig = lpshold(kfreq, ktrig, iphase, kvalue0, ktime0  [, kvalue1] [, ktime1] \
               [, kvalue2] [, ktime2] [...])

ksig lpshold kfreq, ktrig, iphase, kvalue0, ktime0  [, kvalue1] [, ktime1] \
             [, kvalue2] [, ktime2] [...]

Performance

ksig -- Output signal

kfreq -- Repeat rate in Hz or fraction of Hz

ktrig -- If non-zero, retriggers the envelope from start (see trigger opcode), before the envelope cycle is completed.

iphase -- A vaue between 0 and 1 to say where to start the loop. Zero, the commonest value, indicates the beginning.

kvalue0...kvalueN -- Values of points

ktime0...ktimeN -- Times between points; expressed in fractions of a cycle (see below). The final time designates a ramp between the final value and the first value.

lpshold is similar to loopseg, but can generate only horizontal segments, i.e. holds values for each time interval placed between ktimeN and ktimeN+1. It can be useful, among other things, for melodic control, like old analog sequencers.

Examples

Here is an example of the lpshold opcode. It uses the file lpshold.csd.

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

sr = 44100
ksmps = 32
nchnls = 2
0dbfs  = 1

instr 1
kfrq  init    p4  ; frequency of the loop 
ifrac =       p5  ; fraction of frequency at which to force retrigger
ipan  =       p6  ; pan position
ktrig metro   kfrq * ifrac  ; trigger to force restart the loop
iphs  =       0   ; initial phase of the loop
; a loop of midi note numbers:   note duration etc...
knote lpshold kfrq, ktrig, iphs, 61,  0.0625,  60, 0.9375,   61, 1, 58, 1, \
63, 2, 65, 3
aenv  linseg 0,0.01,1,p3-0.11,1,0.1,0   ; amplitude envelope
krnd  rspline -0.05,0.05,0.5,1 ; random detune
asig  gbuzz   0.2*aenv, cpsmidinn(knote+krnd), 30, 1, 0.5, 1 
      outs    asig*ipan, asig*(1-ipan)
endin

</CsInstruments>
<CsScore>
; cosine wave.
f 1 0 16384 11 1

; 3 layers of the loop are played, each at a different speed, 
; - with different retriggering rate, and pan location.
i 1 0 60 0.5   [8/10] 0.5
i 1 0 60 0.375 [8/11] 0.1
i 1 0 60 0.25  [8/13] 0.9
e
</CsScore>
</CsoundSynthesizer>

See also

Linear and Exponential Generators

Credits

Author: Gabriel Maldonado

New in Version 4.13