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{-# LANGUAGE GADTs #-}
module AudioExample where
import Data.IORef
import Control.Monad
import Control.Concurrent
import Data.Int (Int16, Int32)
import SDL
import qualified Data.Vector.Storable.Mutable as V
sinSamples :: [Int16]
sinSamples =
map (\n ->
let t = fromIntegral n / 48000 :: Double
freq = 440
in round (fromIntegral (maxBound `div` 2 :: Int16) * sin (2 * pi * freq * t)))
[0 :: Int32 ..]
audioCB :: IORef [Int16] -> AudioFormat sampleType -> V.IOVector sampleType -> IO ()
audioCB samples format buffer =
case format of
Signed16BitLEAudio ->
do samples' <- readIORef samples
let n = V.length buffer
zipWithM_ (V.write buffer)
[0 ..]
(take n samples')
writeIORef samples
(drop n samples')
_ -> error "Unsupported audio format"
main :: IO ()
main =
do initializeAll
samples <- newIORef sinSamples
(device,_) <-
openAudioDevice
OpenDeviceSpec {SDL.openDeviceFreq =
Mandate 48000
,SDL.openDeviceFormat =
Mandate Signed16BitNativeAudio
,SDL.openDeviceChannels =
Mandate Mono
,SDL.openDeviceSamples = 4096 * 2
,SDL.openDeviceCallback = audioCB samples
,SDL.openDeviceUsage = ForPlayback
,SDL.openDeviceName = Nothing}
setAudioDevicePlaybackState device Play
forever (threadDelay maxBound)
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