-- | FIXME
data DecorrPass
= DecorrPass {
- -- | The decorrelation term: (term /= 0) && ((-3 <= term <= 8)
- -- || (term == 17) || (term <= 18))
+ -- | The decorrelation term: @(term /= 0) && ((-3 <= term <= 8)
+ -- || (term == 17) || (term <= 18))@
dpTerm ∷ !Int8
- -- | The decorrelation delta: 0 <= delta <= 8
+ -- | The decorrelation delta: @0 <= delta <= 8@
, dpDelta ∷ !Int8
- -- | The decorrelation weight for channel A: -1024 <= weight <=
- -- 1024
+ -- | The decorrelation weight for channel A: @-1024 <= weight <=
+ -- 1024@
, dpWeightA ∷ !Int16
- -- | The decorrelation weight for channel B: -1024 <= weight <=
- -- 1024
+ -- | The decorrelation weight for channel B: @-1024 <= weight <=
+ -- 1024@
, dpWeightB ∷ !Int16
-- | The decorrelation samples for channel A.
, dpSamplesA ∷ !(UV.Vector Int32)
, Dummy(..)
, DecorrTerms(..)
+ , DecorrWeights(..)
, RIFFHeader(..)
, RIFFTrailer(..)
, Unknown(..)
return $ runGet (getSubBlock rawID) subb
where
getSubBlock ∷ Word8 → Get SubBlock
- getSubBlock 0x00 = fmap SubBlock (get ∷ Get Dummy )
- getSubBlock 0x02 = fmap SubBlock (get ∷ Get DecorrTerms)
- 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)
-- | Decorrelation terms and deltas.
data DecorrTerms
= DecorrTerms {
- -- | [ (term, delta) ]
+ -- | @[ (term, delta) ]@
dectVec ∷ !(UV.Vector (Int8, Int8))
}
deriving (Eq, Show, Typeable)
.|.
((δ `shiftL` 5) .&. 0xE0)
)
-
get = do n ← remaining
vec ← UV.replicateM (fromIntegral n) $ fmap unpackDT getWord8
-- THINKME: unpack.c(read_decorr_terms) reverses the
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 {