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