X-Git-Url: http://git.cielonegro.org/gitweb.cgi?p=wavpack.git;a=blobdiff_plain;f=Codec%2FAudio%2FWavPack%2FMetadata.hs;h=f88224161d18b7435b40e78a77262060ff4477fe;hp=d8c0df1e592d889c1b203acb5a2ef3dd99d790f5;hb=3750749a13950d505adfcbc328e7a4d6a6a2059c;hpb=5bf7c1be1cfce7ef8764ca3fbc34e8ef9bcf5037

diff --git a/Codec/Audio/WavPack/Metadata.hs b/Codec/Audio/WavPack/Metadata.hs
index d8c0df1..f882241 100644
--- a/Codec/Audio/WavPack/Metadata.hs
+++ b/Codec/Audio/WavPack/Metadata.hs
@@ -11,11 +11,14 @@ 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
@@ -23,6 +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
@@ -94,6 +98,8 @@ instance Binary SubBlock where
           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
@@ -177,35 +183,85 @@ instance Metadata DecorrWeights where
     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'''
+    put = UV.mapM_ (putWord8 ∘ packWeight) ∘ decwVec
     get = do n   ← remaining
-             vec ← UV.replicateM (fromIntegral n) $ fmap unpackW getWord8
+             vec ← UV.replicateM (fromIntegral n)
+                    $ fmap unpackWeight getWord8
              -- THINKME: the same caution as DecorrTerms, but never
-             -- try to reverse the vector simply. Think about the
+             -- 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
-          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'''
+          -- 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