, SubBlock
, Dummy(..)
+ , DecorrTerms(..)
+ , DecorrWeights(..)
, RIFFHeader(..)
, RIFFTrailer(..)
, Unknown(..)
import Data.Binary.Put
import Data.Bits
import qualified Data.ByteString.Lazy as L
+import Data.Int
import Data.Typeable
+import qualified Data.Vector.Unboxed as UV
import Prelude.Unicode
-- | Type class for every metadata sub-blocks.
return $ runGet (getSubBlock rawID) subb
where
getSubBlock ∷ Word8 → Get SubBlock
- getSubBlock 0x00 = fmap SubBlock (get ∷ Get Dummy)
- getSubBlock 0x21 = fmap SubBlock (get ∷ Get RIFFHeader)
- getSubBlock 0x22 = fmap SubBlock (get ∷ Get RIFFTrailer)
+ getSubBlock 0x00 = fmap SubBlock (get ∷ Get Dummy )
+ getSubBlock 0x02 = fmap SubBlock (get ∷ Get DecorrTerms )
+ getSubBlock 0x03 = fmap SubBlock (get ∷ Get DecorrWeights)
+ getSubBlock 0x21 = fmap SubBlock (get ∷ Get RIFFHeader )
+ getSubBlock 0x22 = fmap SubBlock (get ∷ Get RIFFTrailer )
getSubBlock unknownID
= if unknownID .&. 0x20 ≡ 0 then
fail ("Unknown WavPack metadata ID: " ⧺ show unknownID)
put = putLazyByteString ∘ flip L.replicate 0x00 ∘ fromIntegral ∘ dumSize
get = fmap (Dummy ∘ fromIntegral) remaining
+-- | Decorrelation terms and deltas.
+data DecorrTerms
+ = DecorrTerms {
+ -- | @[ (term, delta) ]@
+ dectVec ∷ !(UV.Vector (Int8, Int8))
+ }
+ deriving (Eq, Show, Typeable)
+
+instance Metadata DecorrTerms where
+ metaID _ = 0x02
+ metaSize = fromIntegral ∘ UV.length ∘ dectVec
+
+instance Binary DecorrTerms where
+ put = UV.mapM_ (putWord8 ∘ packDT) ∘ dectVec
+ where
+ packDT ∷ (Int8, Int8) → Word8
+ packDT (term, δ)
+ = fromIntegral ( (term + 5 .&. 0x1F)
+ .|.
+ ((δ `shiftL` 5) .&. 0xE0)
+ )
+ get = do n ← remaining
+ vec ← UV.replicateM (fromIntegral n) $ fmap unpackDT getWord8
+ -- THINKME: unpack.c(read_decorr_terms) reverses the
+ -- order only when they are decoding. I don't know why so
+ -- I leave it unreversed for now.
+ return $ DecorrTerms vec
+ where
+ unpackDT ∷ Word8 → (Int8, Int8)
+ unpackDT w
+ = let term = (fromIntegral $ w .&. 0x1F) - 5
+ δ = fromIntegral $ (w `shiftR` 5) .&. 0x07
+ in
+ (term, δ)
+
+-- | Decorrelation weights.
+data DecorrWeights
+ = DecorrWeights {
+ -- | For mono blocks, this is a weight vector for the single
+ -- channel. For stereo blocks, it's interleaved as A, B, A, B,
+ -- ...
+ decwVec ∷ !(UV.Vector Int16)
+ }
+ deriving (Eq, Show, Typeable)
+
+instance Metadata DecorrWeights where
+ metaID _ = 0x03
+ metaSize = fromIntegral ∘ UV.length ∘ decwVec
+
+instance Binary DecorrWeights where
+ put = UV.mapM_ (putWord8 ∘ packW) ∘ decwVec
+ where
+ packW ∷ Int16 → Word8
+ packW w
+ = let w' | w > 1024 = 1024
+ | w < -1024 = -1024
+ | otherwise = w
+ w'' | w' > 0 = w' - ((w' + 64) `shiftR` 7)
+ | otherwise = w'
+ w''' = (w'' + 4) `shiftR` 3
+ in
+ fromIntegral w'''
+ get = do n ← remaining
+ vec ← UV.replicateM (fromIntegral n) $ fmap unpackW getWord8
+ -- THINKME: the same caution as DecorrTerms, but never
+ -- try to reverse the vector simply. Think about the
+ -- interleaving.
+ return $ DecorrWeights vec
+ where
+ unpackW ∷ Word8 → Int16
+ unpackW w
+ = let w' ∷ Int8
+ w' = fromIntegral w
+ w'' ∷ Int16
+ w'' = (fromIntegral w') `shiftL` 3
+ w''' | w'' > 0 = w'' + ((w'' + 64) `shiftR` 7)
+ | otherwise = w''
+ in
+ w'''
+
-- | RIFF header for .wav files (before audio)
data RIFFHeader
= RIFFHeader {
instance Binary Unknown where
put = putLazyByteString ∘ unkData
- get = (⊥)
+ get = error "unsupported operation"