-- Example 7 - Communicating continuous values with Csound's Channel System

-- Author: Steven Yi <stevenyi@gmail.com>

-- 2013.10.28

--

-- This example introduces using Csound's Channel System to communicate

-- continuous control data (k-rate) from a host program to Csound. The

-- first thing to note is the RandomLine class. It takes in a base value

-- and a range in which to vary randomly. The reset functions calculates

-- a new random target value (self.end), a random duration in which to

-- run (self.dur, expressed as -- of audio blocks to last in duration), and

-- calculates the increment value to apply to the current value per audio-block.

-- When the target is met, the Randomline will reset itself to a new target

-- value and duration.

--

-- In this example, we use two RandomLine objects, one for amplitude and

-- another for frequency. We start a Csound instrument instance that reads

-- from two channels using the chnget opcode. In turn, we update the values

-- to the channel from the host program. In this case, because we want to

-- keep our values generating in sync with the audio engine, we use a

-- while-loop instead of a CsoundPerformanceThread. To update the channel,

-- we call the SetChannel method on the Csound object, passing a channel name

-- and value. Note: The getValue method on the RandomLine not only gets

-- us the current value, but also advances the internal state by the increment

-- and by decrementing the duration.

require "luaCsnd6"

local RandomLine = {}

function RandomLine:new(base, range)

local o = {}

setmetatable(o, self)

self.__index = self

o.curVal = 0.0

o:reset()

o.base = base

o.range = range

return o

end

function RandomLine:reset()

self.dur = math.random(256,512)

self.End = math.random()

self.increment = (self.End - self.curVal) / self.dur

end

function RandomLine:getValue()

self.dur = self.dur - 1

if(self.dur < 0) then

self:reset()

end

retVal = self.curVal

self.curVal = self.curVal + self.increment

return self.base + (self.range * retVal)

end

-- Our Orchestra for our project

orc = [[

sr=44100

ksmps=32

nchnls=2

0dbfs=1

instr 1

kamp chnget "amp"

kfreq chnget "freq"

printk 0.5, kamp

printk 0.5, kfreq

aout vco2 kamp, kfreq

aout moogladder aout, 2000, 0.25

outs aout, aout

endin

]]

local c = luaCsnd6.Csound() -- create an instance of Csound

c:SetOption("-odac") -- Set option for Csound

c:SetOption("-m7") -- Set option for Csound

c:CompileOrc(orc) -- Compile Orchestra from String

local sco = "i1 0 60\n"

c:ReadScore(sco) -- Read in Score generated from notes

c:Start() -- When compiling from strings, this call is necessary before doing any performing

-- The following is our main performance loop. We will perform one block of sound at a time

-- and continue to do so while it returns 0, which signifies to keep processing.

amp = RandomLine:new(.4, .2) -- create RandomLine for use with Amplitude

freq = RandomLine:new(400, 80) -- create RandomLine for use with Frequency

c:SetChannel("amp", amp:getValue()) -- Initialize channel value before running Csound

c:SetChannel("freq", freq:getValue()) -- Initialize channel value before running Csound

--print(amp:getValue())

--print(freq:getValue())

while (c:PerformKsmps() == 0) do

c:SetChannel("amp", amp:getValue()) -- update channel value

c:SetChannel("freq", freq:getValue()) -- update channel value

end

c:Stop()