# Example 8 - More efficient Channel Communications

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

# 2013.10.28

#

# This example builds on Example 7 by replacing the calls to SetChannel

# with using GetChannelPtr. In the Csound API, using SetChannel and GetChannel

# is great for quick work, but ultimately it is slower than pre-fetching the

# actual channel pointer. This is because Set/GetChannel operates by doing a

# lookup of the Channel Pointer, then setting or getting the value. This

# happens on each call. The alternative is to use GetChannelPtr, which fetches

# the Channel Pointer and lets you directly set and get the value on the pointer.

#

# In C/C++/Objective-C, one can directly use MYFLT* to get/set values. However,

# for wrapped languages such as Python, Java, and Lua, it is generally not possible

# to get/set the value on the pointer itself. The Csound API for host languages

# uses a special wrapper object called CsoundMYFLTArray, which will hold a reference

# to a MYFLT*. The CsoundMYFLTArray in turn has convenience methods for setting

# and getting values.

#

# The code below shows how to use the CsoundMYFLTArray in conjunction with GetChannelPtr

# to have a more optimized channel setting system.

import csnd6

from random import randint, random

class RandomLine(object):

def __init__(self, base, range):

self.curVal = 0.0

self.reset()

self.base = base

self.range = range

def reset(self):

self.dur = randint(256,512)

self.end = random()

self.slope = (self.end - self.curVal) / self.dur

def getValue(self):

self.dur -= 1

if(self.dur < 0):

self.reset()

retVal = self.curVal

self.curVal += self.slope

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

# 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"""

c = csnd6.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

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

ampChannel = csnd6.CsoundMYFLTArray(1) # create a CsoundMYFLTArray of size 1

freqChannel = csnd6.CsoundMYFLTArray(1) # create a CsoundMYFLTArray of size 1

# the following calls store the Channel Pointer retreived from Csound into the

# CsoundMYFLTArray Objects

c.GetChannelPtr(ampChannel.GetPtr(), "amp",

csnd6.CSOUND_CONTROL_CHANNEL | csnd6.CSOUND_INPUT_CHANNEL)

c.GetChannelPtr(freqChannel.GetPtr(), "freq",

csnd6.CSOUND_CONTROL_CHANNEL | csnd6.CSOUND_INPUT_CHANNEL)

amp = RandomLine(.4, .2)

freq = RandomLine(400, 80)

ampChannel.SetValue(0, amp.getValue()) # note we are now setting values on the CsoundMYFLTArray

freqChannel.SetValue(0, freq.getValue())

#print amp.getValue()

#print freq.getValue()

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

ampChannel.SetValue(0, amp.getValue())

freqChannel.SetValue(0, freq.getValue())

c.Stop()