Playing around with audio

sine.hs

module Main where

import Data.Binary.Put
import qualified Data.ByteString.Lazy as BL
import Data.Word

newtype Seconds = Seconds Double
newtype Hertz = Hertz Double

sampleRate :: Double
sampleRate = 16000
{-# INLINE sampleRate #-}

nextPhase :: Double -> Hertz -> Double
nextPhase phase (Hertz f) = phase + ((2 * pi * f) / sampleRate)
{-# INLINE nextPhase #-}

produceSeconds :: Seconds -> Hertz -> [Double]
produceSeconds (Seconds s) h =
  take (floor (sampleRate * s)) . map sin $
  iterate (flip nextPhase h) 0
{-# INLINE produceSeconds #-}

volumeize :: Word16 -> [Double] -> [Double]
volumeize m l = map (fromIntegral m *) l
{-# INLINE volumeize #-}

toWord16 :: [Double] -> [Word16]
toWord16 = map round
{-# INLINE toWord16 #-}

putSamples :: [Word16] -> Put
putSamples l = mapM_ putWord16le l
{-# INLINE putSamples #-}

main :: IO ()
main = do
  let r = toWord16 . volumeize (maxBound `div` 2) $ produceSeconds (Seconds 1) (Hertz 1000)
  BL.writeFile "/tmp/out.raw" (runPut . putSamples $ r)