EntropyVars

[wavpack.git] / Codec / Audio / WavPack / Metadata.hs

diff --git a/Codec/Audio/WavPack/Metadata.hs b/Codec/Audio/WavPack/Metadata.hs
index 601d42e666b8d45b2e68be9b28b9424af5feafec..f88224161d18b7435b40e78a77262060ff4477fe 100644 (file)
--- a/Codec/Audio/WavPack/Metadata.hs
+++ b/Codec/Audio/WavPack/Metadata.hs
@@ -10,11 +10,15 @@ module Codec.Audio.WavPack.Metadata
 
     , Dummy(..)
     , DecorrTerms(..)
+    , DecorrWeights(..)
+    , DecorrSamples(..)
+    , EntropyVars(..)
     , RIFFHeader(..)
     , RIFFTrailer(..)
     , Unknown(..)
     )
     where
+import Codec.Audio.WavPack.Internal
 import Control.Monad
 import Data.Binary
 import Data.Binary.Get
@@ -22,6 +26,7 @@ import Data.Binary.Put
 import Data.Bits
 import qualified Data.ByteString.Lazy as L
 import Data.Int
+import qualified Data.Strict as S
 import Data.Typeable
 import qualified Data.Vector.Unboxed as UV
 import Prelude.Unicode
@@ -90,10 +95,13 @@ instance Binary SubBlock where
              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 0x04 = fmap SubBlock (get ∷ Get DecorrSamples)
+          getSubBlock 0x05 = fmap SubBlock (get ∷ Get EntropyVars  )
+          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)
@@ -128,7 +136,7 @@ instance Binary Dummy where
 -- | Decorrelation terms and deltas.
 data DecorrTerms
     = DecorrTerms {
-        -- | [ (term, delta) ]
+        -- | @[ (term, delta) ]@
         dectVec ∷ !(UV.Vector (Int8, Int8))
       }
     deriving (Eq, Show, Typeable)
@@ -146,7 +154,6 @@ instance Binary DecorrTerms where
                                .|.
                                ((δ `shiftL` 5) .&. 0xE0)
                              )
-
     get = do n   ← remaining
              vec ← UV.replicateM (fromIntegral n) $ fmap unpackDT getWord8
              -- THINKME: unpack.c(read_decorr_terms) reverses the
@@ -161,6 +168,101 @@ instance Binary DecorrTerms where
                 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 ∘ packWeight) ∘ decwVec
+    get = do n   ← remaining
+             vec ← UV.replicateM (fromIntegral n)
+                    $ fmap unpackWeight getWord8
+             -- THINKME: the same caution as DecorrTerms, but never
+             -- try to simply reverse the vector. Think about the
+             -- interleaving.
+             return $ DecorrWeights vec
+
+-- | Decorrelation samples
+data DecorrSamples
+    = DecorrSamples {
+      -- | The decorrelation sample vector stored in the metadata
+      --   as-is. Actual interpretation of the vector depends on the
+      --   number of channels and each corresponding decorrelation
+      --   terms.
+        decsVec ∷ !(UV.Vector Int32)
+      }
+    deriving (Eq, Show, Typeable)
+
+instance Metadata DecorrSamples where
+    metaID _ = 0x04
+    metaSize = fromIntegral ∘ (⋅ 2) ∘ UV.length ∘ decsVec
+
+instance Binary DecorrSamples where
+    put = UV.mapM_ (putWord16le ∘ fromIntegral ∘ log2s) ∘ decsVec
+    get = do n   ← remaining
+             vec ← UV.replicateM (fromIntegral $ n `div` 2)
+                    $ fmap (exp2s ∘ fromIntegral) getWord16le
+             return $ DecorrSamples vec
+
+-- | Median log2 values.
+data EntropyVars
+    = EntropyVars {
+      -- | Median log2 values for channel A, which always exists.
+        entVarA ∷ !(Word32, Word32, Word32)
+      -- | Median log2 values for channel B, which is absent when it's
+      --   mono.
+      , entVarB ∷ !(S.Maybe (Word32, Word32, Word32))
+      }
+    deriving (Eq, Show, Typeable)
+
+instance Metadata EntropyVars where
+    metaID _ = 0x05
+    metaSize ev
+        | S.isNothing $ entVarB ev =  6
+        | otherwise                = 12
+
+instance Binary EntropyVars where
+    put ev
+        = do putMedians $ entVarA ev
+             case entVarB ev of
+               S.Nothing    → return ()
+               S.Just medsB → putMedians medsB
+        where
+          -- THINKME: words.c(write_entropy_vars) is a destructive
+          -- subroutine. It calls read_entropy_vars() to read the
+          -- values back to compensate for the loss through the log
+          -- function.
+          putMedians ∷ (Word32, Word32, Word32) → Put
+          putMedians (med0, med1, med2)
+              = do putWord16le $ log2 med0
+                   putWord16le $ log2 med1
+                   putWord16le $ log2 med2
+
+    get = do medsA ← getMedians
+             medsB ← do isMono ← isEmpty
+                        if isMono then
+                            return S.Nothing
+                          else
+                            fmap S.Just getMedians
+             return $! EntropyVars medsA medsB
+        where
+          getMedians ∷ Get (Word32, Word32, Word32)
+          getMedians
+              = do med0 ← fmap exp2 getWord16le
+                   med1 ← fmap exp2 getWord16le
+                   med2 ← fmap exp2 getWord16le
+                   return (med0, med1, med2)
+
 -- | RIFF header for .wav files (before audio)
 data RIFFHeader
     = RIFFHeader {