#----------------------------------------------------------------------
# Generation of pure sine tones
#
# Copyright (C) April 18, 2017 -- Dr. William T. Verts
#----------------------------------------------------------------------
# From page 330 of the Companion.
#
# There are three questions that must be answered when processing
# or generating sounds digitally:
#
# Question #1: How many independent channels?  
#              (1 for mono or 2 for stereo, JES defaults to 1)
#
# Question #2: How good is each sample?
#              (1 or 2 bytes/sample, JES defaults to 2)
#
#              1 byte/sample:  Values range from -128...+127
#                              (256 levels, OK for voice)
#
#              2 bytes/sample: Values range from -32768...+32767
#                              (65536 levels, OK for music)
#
# Question #3: How many samples/second/channel do we need?
#
#   3A: What is the highest frequency humans can hear?
#              22000 Hz (cycles/second)   or   22KHz
#
#   3B: How does frequency relate to samples/second?
#              Nyquist's Sampling Theorem:
#              to reproduce a signal, sample > 2X
#              the highest desired frequency.
#
# For CDs:
#  (2 channels) * (2 bytes/sample) * (44100 samples/second/channel) =
#  176400 bytes/second
#
# We will then use 44100 as our default sampling rate.  We could make
# it smaller if we chose.
#
# JES function makeEmptySoundBySeconds requires an integer number
# of seconds.  To make this a float, we have to manually compute the
# number of needed samples using the number of seconds, the sampling
# rate, and JES function makeEmptySound.
#----------------------------------------------------------------------

def SineWave (Frequency, Seconds, Volume=32767.0, SamplingRate=44100):
#   MySound = makeEmptySoundBySeconds(int(Seconds), SamplingRate)
    MySound = makeEmptySound(int(Seconds*SamplingRate), SamplingRate)
    TotalSamples = getNumSamples(MySound)
    RadiansPerSample = (2.0 * pi) * Frequency / SamplingRate
    for MySample in range(TotalSamples):
        Angle = MySample * RadiansPerSample
        setSampleValueAt(MySound, MySample, int(Volume * sin(Angle)))
    return MySound

#----------------------------------------------------------------------
# Play the 5-tone sequence from "Close Encounters of the Third Kind".
# JES function blockingPlay will only play one sound at a time.
# If we used the JES play function instead, all sounds would play
# simultaneously.
#----------------------------------------------------------------------
    
def CloseEncounters ():
    for F in [882, 990, 786, 393, 588]:
        blockingPlay(SineWave(F, 0.5))
    return