source: 3DVCSoftware/branches/HTM-4.0-Nokia/source/Lib/TLibCommon/ContextModel.cpp @ 138

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/** \file     ContextModel.cpp
    \brief    context model class
*/

#include <algorithm>

#include "ContextModel.h"

using namespace std;
//! \ingroup TLibCommon
//! \{

// ====================================================================================================================
// Public member functions
// ====================================================================================================================

/**
 - initialize context model with respect to QP and initialization value
 .
 \param  qp         input QP value
 \param  initValue  8 bit initialization value
 */
Void ContextModel::init( Int qp, Int initValue )
{
#if H0736_AVC_STYLE_QP_RANGE
  qp = Clip3(0, 51, qp);
#endif

#if CABAC_LINEAR_INIT
  Int  slope      = (initValue>>4)*5 - 45;
  Int  offset     = ((initValue&15)<<3)-16;
  Int  initState  =  min( max( 1, ( ( ( slope * qp ) >> 4 ) + offset ) ), 126 );
  UInt mpState    = (initState >= 64 );
  m_ucState       = ( (mpState? (initState - 64):(63 - initState)) <<1) + mpState;
#else
  Int m = m_slopes[initValue>>4];
  Int n = initValue & 15;
  
  Int val = max( 0, min( 3839, (n<<8) + m * (qp-26) + 128 ) );
  val -= 1920;
  Int valMps = val >= 0;
  val = ( val ^ (val>>11) ) + 128;
  Int segmentIdx = val >> 8;
  Int pStateIdx = m_accumulatedSegOffset[segmentIdx] + ( (val&255) * m_segOffset[segmentIdx] >> 8);
  
  m_ucState = (pStateIdx<<1) + valMps;
#endif
}

const UChar ContextModel::m_aucNextStateMPS[ 128 ] =
{
  2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
  18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
  34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
  50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,
  66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81,
  82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97,
  98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113,
  114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 124, 125, 126, 127
};

const UChar ContextModel::m_aucNextStateLPS[ 128 ] =
{
  1, 0, 0, 1, 2, 3, 4, 5, 4, 5, 8, 9, 8, 9, 10, 11,
  12, 13, 14, 15, 16, 17, 18, 19, 18, 19, 22, 23, 22, 23, 24, 25,
  26, 27, 26, 27, 30, 31, 30, 31, 32, 33, 32, 33, 36, 37, 36, 37,
  38, 39, 38, 39, 42, 43, 42, 43, 44, 45, 44, 45, 46, 47, 48, 49,
  48, 49, 50, 51, 52, 53, 52, 53, 54, 55, 54, 55, 56, 57, 58, 59,
  58, 59, 60, 61, 60, 61, 60, 61, 62, 63, 64, 65, 64, 65, 66, 67,
  66, 67, 66, 67, 68, 69, 68, 69, 70, 71, 70, 71, 70, 71, 72, 73,
  72, 73, 72, 73, 74, 75, 74, 75, 74, 75, 76, 77, 76, 77, 126, 127
};

#if FAST_BIT_EST
UChar ContextModel::m_nextState[128][2];

Void ContextModel::buildNextStateTable()
{
  for (Int i = 0; i < 128; i++)
  {
    for (Int j = 0; j < 2; j++)
    {
      m_nextState[i][j] = ((i&1) == j) ? m_aucNextStateMPS[i] : m_aucNextStateLPS[i];
    }
  }
}
#endif

const Int ContextModel::m_entropyBits[128] =
{
#if FAST_BIT_EST
  // Corrected table, most notably for last state
  0x07b23, 0x085f9, 0x074a0, 0x08cbc, 0x06ee4, 0x09354, 0x067f4, 0x09c1b, 0x060b0, 0x0a62a, 0x05a9c, 0x0af5b, 0x0548d, 0x0b955, 0x04f56, 0x0c2a9,
  0x04a87, 0x0cbf7, 0x045d6, 0x0d5c3, 0x04144, 0x0e01b, 0x03d88, 0x0e937, 0x039e0, 0x0f2cd, 0x03663, 0x0fc9e, 0x03347, 0x10600, 0x03050, 0x10f95,
  0x02d4d, 0x11a02, 0x02ad3, 0x12333, 0x0286e, 0x12cad, 0x02604, 0x136df, 0x02425, 0x13f48, 0x021f4, 0x149c4, 0x0203e, 0x1527b, 0x01e4d, 0x15d00,
  0x01c99, 0x166de, 0x01b18, 0x17017, 0x019a5, 0x17988, 0x01841, 0x18327, 0x016df, 0x18d50, 0x015d9, 0x19547, 0x0147c, 0x1a083, 0x0138e, 0x1a8a3,
  0x01251, 0x1b418, 0x01166, 0x1bd27, 0x01068, 0x1c77b, 0x00f7f, 0x1d18e, 0x00eda, 0x1d91a, 0x00e19, 0x1e254, 0x00d4f, 0x1ec9a, 0x00c90, 0x1f6e0,
  0x00c01, 0x1fef8, 0x00b5f, 0x208b1, 0x00ab6, 0x21362, 0x00a15, 0x21e46, 0x00988, 0x2285d, 0x00934, 0x22ea8, 0x008a8, 0x239b2, 0x0081d, 0x24577,
  0x007c9, 0x24ce6, 0x00763, 0x25663, 0x00710, 0x25e8f, 0x006a0, 0x26a26, 0x00672, 0x26f23, 0x005e8, 0x27ef8, 0x005ba, 0x284b5, 0x0055e, 0x29057,
  0x0050c, 0x29bab, 0x004c1, 0x2a674, 0x004a7, 0x2aa5e, 0x0046f, 0x2b32f, 0x0041f, 0x2c0ad, 0x003e7, 0x2ca8d, 0x003ba, 0x2d323, 0x0010c, 0x3bfbb
#else
  0x08000, 0x08000, 0x076da, 0x089a0, 0x06e92, 0x09340, 0x0670a, 0x09cdf, 0x06029, 0x0a67f, 0x059dd, 0x0b01f, 0x05413, 0x0b9bf, 0x04ebf, 0x0c35f,
  0x049d3, 0x0ccff, 0x04546, 0x0d69e, 0x0410d, 0x0e03e, 0x03d22, 0x0e9de, 0x0397d, 0x0f37e, 0x03619, 0x0fd1e, 0x032ee, 0x106be, 0x02ffa, 0x1105d,
  0x02d37, 0x119fd, 0x02aa2, 0x1239d, 0x02836, 0x12d3d, 0x025f2, 0x136dd, 0x023d1, 0x1407c, 0x021d2, 0x14a1c, 0x01ff2, 0x153bc, 0x01e2f, 0x15d5c,
  0x01c87, 0x166fc, 0x01af7, 0x1709b, 0x0197f, 0x17a3b, 0x0181d, 0x183db, 0x016d0, 0x18d7b, 0x01595, 0x1971b, 0x0146c, 0x1a0bb, 0x01354, 0x1aa5a,
  0x0124c, 0x1b3fa, 0x01153, 0x1bd9a, 0x01067, 0x1c73a, 0x00f89, 0x1d0da, 0x00eb7, 0x1da79, 0x00df0, 0x1e419, 0x00d34, 0x1edb9, 0x00c82, 0x1f759,
  0x00bda, 0x200f9, 0x00b3c, 0x20a99, 0x00aa5, 0x21438, 0x00a17, 0x21dd8, 0x00990, 0x22778, 0x00911, 0x23118, 0x00898, 0x23ab8, 0x00826, 0x24458,
  0x007ba, 0x24df7, 0x00753, 0x25797, 0x006f2, 0x26137, 0x00696, 0x26ad7, 0x0063f, 0x27477, 0x005ed, 0x27e17, 0x0059f, 0x287b6, 0x00554, 0x29156,
  0x0050e, 0x29af6, 0x004cc, 0x2a497, 0x0048d, 0x2ae35, 0x00451, 0x2b7d6, 0x00418, 0x2c176, 0x003e2, 0x2cb15, 0x003af, 0x2d4b5, 0x0037f, 0x2de55
#endif
};
#if !CABAC_LINEAR_INIT
const Int ContextModel::m_slopes[16] = { -239, -143, -85, -51, -31, -19, -11, 0, 11, 19, 31, 51, 85, 143, 239, 399 };
const Int ContextModel::m_segOffset[8]            = {   6,  7,  5,  7, 10, 14, 16,  1 };
const Int ContextModel::m_accumulatedSegOffset[8] = {  -3,  3, 10, 15, 22, 32, 46, 62 };
#endif
//! \}