# Solution to I590/N560 tuneR assignment #1 of 15 Sep. 2006 - OS X version - Don Byrd

# Load the tuneR package. (This assumes that the package is already installed. If it's
# not, type "install.packages()" and choose tuneR from the list of packages displayed.)
# Warning: in tuneR, 16-bit sample values beyond [-32767,32768] cause errors in later
# processing. In contrast, with the earlier "sound" package, those values are simply clipped.
library(tuneR)

# With OS X, must setWavPlayer() before giving the "play" command -- but to what? QuickTime
# Player works, but gives error messages, makes you hit the escape key to continue, and leaves
# a new copy of the QuickTime Player open each time you use it. There must be a better way!
setWavPlayer("/Applications/'QuickTime Player.app'/Contents/MacOS/'QuickTime Player'")  # OS X: works, but...??
# setWavPlayer("C:/Progra~1/QuickTime/QuickTimePlayer.exe")  # Windows: unnecessary but it works

setwd("Documents/Music+AudioIR+DLs/IowaMusInstSamples")  # OS X (Don's G4; use YOUR path!)
# setwd("Desktop/TODAY")  # OS X (M373 Mac)
# setwd("Music/Teaching-N560Demo/RProgramming") # Windows (Don's PC)

# Get the audio file. (This note, recorded in stereo, is from http://theremin.music.uiowa.edu/MIS.html .)
wav = readWave("Piano.mf1st5sec.A4.wav")  # wav is an object of type Wave
plot(wav, nr=1000)  # another way to display a waveform: gives an overview of whole sound 
play(wav)

# Convert to mono, and make copies of a few things for later use.
wavmono = mono(wav, "both")  # convert stereo to mono by averaging the channels
sampdata = wavmono@left  # get the samples (the right channel is empty for mono sounds)

sampleRate = wav@samp.rate
bitsPerSample = wav@bit
len = length(sampdata)

# Problem 1. Multiply all samples by -1, i.e., change phase 180 degrees: should have no audible effect.
sampdataNeg = sampdata*(-1)
# wav@left[9001:9020]
# sampdata[9001:9020]
# sampdataNeg[9001:9020]
plot(sampdataNeg[0:sampleRate])

wav1 = Wave(left=sampdataNeg, samp.rate=sampleRate, bit=bitsPerSample);  # make a Wave object from sample data
play(wav1)

# Problem 2. Make a sound consisting of five copies of the first 100 millisec.
sampdata100ms = sampdata[0:round(sampleRate*0.1)]
sampdata2 = c(sampdata100ms, sampdata100ms, sampdata100ms, sampdata100ms, sampdata100ms)
plot(sampdata2)
wav2 = Wave(left=sampdata2, samp.rate=sampleRate, bit=bitsPerSample);  # make a Wave object from sample data
play(wav2)

# Problem 3. Make a sound consisting of every third sample of the original.
sampdata3 = sampdata[seq(3, len, by=3)]
plot(sampdata3)
wav3 = Wave(left=sampdata3, samp.rate=sampleRate, bit=bitsPerSample);  # make a Wave object from sample data
play(wav3)

# Problem 4. Make two copies of the sample file overlap with a 10 millisec. offset
padding = seq(from=0, to=0, length.out=0.01*sampleRate)
# padding = seq(from=0, to=0, length.out=0.05*sampleRate)  # a more interesting effect
sampdataThenPadding = c(sampdata, padding)
paddingThenSampdata = c(padding, sampdata)
sampdata4 = sampdataThenPadding+paddingThenSampdata
plot(sampdata4[0:sampleRate])
wav4 = Wave(left=sampdata4, samp.rate=sampleRate, bit=bitsPerSample);  # make a Wave object from sample data
play(wav4)