minecraft@univac2:/srv/minecraft/forge$ cat world/computer/0/usr/playsound.lua
args = {...}
if #args < 2 then
 print("usage: playsound side soundfile")
 return
end

local side = args[1]
if peripheral.getType(side) ~= "speaker" then
 print("no speaker connected at side "..side)
 return
end

local fileName = shell.resolve(args[2])
if not fs.exists(fileName) then
 print("file "..fileName.." does not exist")
 return
end

notes = "cCdDefFgGaAb"
length = 4
tempo = 125
octave = 0
instrument = "flute"
function playString(str)
 if string.len(str) < 1 then return end
 for i=1,string.len(str) do
  chr = string.match(str,".",i)
  if chr == "<" then
   octave = octave - 1
  elseif chr == ">" then
   octave = octave + 1
  elseif chr == "l" then
   i = i + 1
   length = string.match(str,"(%d+)",i)
  elseif chr == "t" then
   i = i + 1
   tempo = string.match(str,"(%d+)",i)
  elseif string.find(notes,chr) then
   local wait = 60 / tempo / (length/4)
   local note = string.find(notes,chr) + 5 + octave * 12
   print(chr.." "..note)
   peripheral.call(side,"playNote",instrument,1,note)
   os.sleep(wait)
  end
 end
end

local f = fs.open(fileName, "r")
while true do
 local str = f.readLine()
 if not str then break end
 print(str)
 playString(str)
end
f.close()