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Src/vlb/prediction.h

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+/* $Header: /cvs/root/winamp/vlb/prediction.h,v 1.1 2009/04/28 20:21:10 audiodsp Exp $ */
+
+#ifdef MAIN_PROFILE
+
+/***************************************************************************\ 
+ *
+ *           Copyright 2000-2002 Dolby Laboratories, Inc.  All Rights 
+ *                Reserved.  Do not copy.  Do not distribute.  
+ *                     Confidential information.
+ *
+ *           (C) copyright Fraunhofer - IIS (1998)
+ *                All Rights Reserved
+ *
+ *   filename: prediction.h
+ *   project : MPEG-2 AAC Decoder
+ *   contents/description: prediction tool
+ *
+\***************************************************************************/
+
+#ifndef __PREDICTION_H__
+#define __PREDICTION_H__
+
+#define DWORDCAST(x) (*(unsigned int*)&(x))
+#define FLOATCAST(x) (*(float*)&(x))
+
+class CChannelInfo ;
+class CBlock ;
+
+/** Intra Channel Prediction.
+
+    This class represents the MPEG-2 AAC Main Profile intra channel prediction
+    tool. It holds the state information for a second order backward-adaptive
+    lattice structure predictor for each spectral component, and can be applied
+    to the spectral coefficients in the main profile only.
+
+    Prediction is a profile-dependent tool and the CPrediction implementation
+    follows the Read()/Apply() convention used for all tools.
+*/
+
+class CPrediction
+{
+public :
+
+  CPrediction () ;
+  ~CPrediction () ;
+
+  void Apply (const CChannelInfo &info, CBlock &spectrum) ;
+
+  void FullReset (void) ;
+
+  enum
+  {
+    MaximumPredictedBins = 672,
+    Order = 2 // Order of the backward adaptive lattice filter
+  } ;
+
+protected :
+
+  class CQuantizedFloat
+  {
+    public :
+
+      operator float () const
+      {
+        return FLOATCAST(m_Value) ;
+      }
+
+      CQuantizedFloat &operator=(float assigned)
+      {
+        m_Value = DWORDCAST(assigned) & 0xFFFF0000 ;
+        return *this ;
+      }
+
+      float GetBDivVar (void) ;
+      
+    protected :
+
+      unsigned int m_Value ;
+
+      static const float m_Mantissa [128] ;
+      static const float m_Exponent [256] ;
+
+  } ;
+
+  // State variables of the backward adaptive predictor
+  // (according to lattice structure in IS)
+
+  class CPredictionState
+  {
+    public :
+
+      CPredictionState ()
+      {
+        Reset () ;
+      }
+
+      ~CPredictionState () {}
+
+      float GetPredictedValue (void) ;
+      void Update (float value) ;
+
+      void Reset (void)
+      {
+        for (int i = 0 ; i < Order ; i++)
+        {
+          m_cor [i] = 0.0F ;
+          m_var [i] = 1.0F ;
+          m_r   [i] = 0.0F ;
+        }
+      }
+
+    protected :
+
+      float FloatRoundInfinity (float x) ;
+
+      CQuantizedFloat m_r   [Order] ; // r coefficient
+      CQuantizedFloat m_cor [Order] ; // correlation coefficient
+      CQuantizedFloat m_var [Order] ; // variance coefficient
+
+  } ;
+
+  CPredictionState m_State [MaximumPredictedBins] ;
+
+} ;
+
+#endif
+#endif