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{-# LANGUAGE RecordWildCards #-}
import Foreign.C.Types (CFloat(..))
import qualified Sound.JACK as Jack
import qualified Sound.JACK.Audio as Audio
import Options.Applicative
import Data.Maybe
import System.Directory
import System.FilePath
import System.Posix.Files
import System.Posix.IO
import System.Environment
import Control.Concurrent
import Control.Concurrent.MVar
import qualified Control.Monad.Trans.Class as Trans
import Control.Exception
import System.IO.Error
import System.INotify
data Options = Options
{ input :: String
, output :: String
, initialLevel :: Float
, stateDir :: FilePath
}
optionParser :: Parser Options
optionParser = Options <$>
strOption ( long "input"
<> metavar "JACK"
)
<*> strOption ( long "output"
<> metavar "JACK"
)
<*> (fromMaybe 0 <$> optional (option auto ( long "level"
<> metavar "FLOAT"
)
)
)
<*> strOption ( long "dir"
<> metavar "DIRECTORY"
)
main :: IO ()
main = execParser opts >>= trivmix
where
opts = info (helper <*> optionParser)
( fullDesc
<> progDesc "Setup a JACK mixing input/output pair controlled by fifos in a state directory"
<> header "Trivmix - A trivial mixer"
)
trivmix :: Options -> IO ()
trivmix Options{..} = do
name <- getProgName
createDirectoryIfMissing True stateDir
level <- newMVar initialLevel
let levelFile = stateDir </> "level"
onLevelFile levelFile initialLevel $ withINotify $ \n -> do
addWatch n [Modify] levelFile (const $ handleLevel level levelFile)
Jack.handleExceptions $
Jack.withClientDefault name $ \client ->
Jack.withPort client input $ \input' ->
Jack.withPort client output $ \output' ->
Audio.withProcessMono client input' (mix level) output' $
Jack.withActivation client $ Trans.lift $ do
Jack.waitForBreak
mix :: MVar Float -> CFloat -> IO CFloat
mix level input = do
level' <- readMVar level
return $ (CFloat level') * input
onLevelFile :: FilePath -> Float -> IO a -> IO a
onLevelFile file initial action = do
exists <- doesFileExist file
let acquire = case exists of
True -> return ()
False -> createFile file mode >>= closeFd
mode = foldl unionFileModes nullFileMode [ ownerReadMode
, ownerWriteMode
, groupReadMode
, groupWriteMode
]
release = case exists of
True -> return ()
False -> removeFile file
bracket_ acquire release action
handleLevel :: MVar Float -> FilePath -> IO ()
handleLevel level file = catch action handler
where
action = readFile file >>= readIO >>= swapMVar level >>= const (return ())
handler e = if isUserError e
then readMVar level >>= \l -> writeFile file (show l)
else throw e
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