cabac.c

JM 11.0 KTA 2.1 Source Code

  if (coeff_ctr)
  {
    //--- set run and level (coefficient) ---
    for (se->value2=0; coeff[pos]==0; pos++, se->value2++);
    se->value1=coeff[pos++];
  }
  else
  {
    //--- set run and level (EOB) ---
    se->value1 = se->value2 = 0;
  }
  //--- decrement coefficient counter and re-set position ---
  if (coeff_ctr-- == 0) pos=0;

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\t%d\n",symbolCount++, se->tracestring, se->value1,se->value2);
  fflush(p_trace);
#endif
}
#else
/*!
 ************************************************************************
 * \brief
 *    Read Block-Transform Coefficients
 ************************************************************************
 */
void readRunLevel_CABAC (SyntaxElement  *se,
                         struct inp_par *inp,
                         struct img_par *img,    
                         DecodingEnvironmentPtr dep_dp)
{
#ifdef USE_INTRA_MDDT
  static int  coeff[256]; // one more for EOB
#else
  static int  coeff[64]; // one more for EOB
#endif
  static int  coeff_ctr = -1;
  static int  pos       =  0;

  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  //--- read coefficients for whole block ---
  if (coeff_ctr < 0)
  {
    //===== decode CBP-BIT =====
    if ((coeff_ctr = read_and_store_CBP_block_bit (currMB, dep_dp, img, se->context)))
    {
      //===== decode significance map =====
      coeff_ctr = read_significance_map (currMB, dep_dp, img, se->context, coeff);

      //===== decode significant coefficients =====
      read_significant_coefficients     (currMB, dep_dp, img, se->context, coeff);
    }
  }

  //--- set run and level ---
  if (coeff_ctr)
  {
    //--- set run and level (coefficient) ---
    for (se->value2=0; coeff[pos]==0; pos++, se->value2++);
    se->value1=coeff[pos++];
  }
  else
  {
    //--- set run and level (EOB) ---
    se->value1 = se->value2 = 0;
  }
  //--- decrement coefficient counter and re-set position ---
  if (coeff_ctr-- == 0) pos=0;

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\t%d\n",symbolCount++, se->tracestring, se->value1,se->value2);
  fflush(p_trace);
#endif
}
#endif

#ifdef USE_INTRA_MDDT
/*! 
*************************************************************************************
* \brief
*   read all the runs and levels of an INTRA16x16 macroblock
*
* \para writeRunLevel16x16_CABAC()
*    <paragraph>
*
* \author
*    - Yan Ye                      <[e-mail]>
*************************************************************************************
*/
void readRunLevel16x16_CABAC (SyntaxElement  *se,
                              struct inp_par *inp,
                              struct img_par *img,    
                              DecodingEnvironmentPtr dep_dp)
{
  static int  coeff[256]; // one more for EOB
  static int  coeff_ctr = -1;
  static int  pos       =  0;

  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  // set all block CBP to 1
  set_CBP_block_bit_16x16(currMB);

  //--- read coefficients for whole block ---
  if (coeff_ctr < 0)
  {
    //===== decode CBP-BIT =====
    // for 16x16, block must be coded when here
    //if ((coeff_ctr = read_and_store_CBP_block_bit (currMB, dep_dp, img, se->context)))
    {
      //===== decode significance map =====
      coeff_ctr = read_significance_map (currMB, dep_dp, img, se->context, coeff);

      //===== decode significant coefficients =====
      read_significant_coefficients     (currMB, dep_dp, img, se->context, coeff);
    }
  }
  //--- set run and level ---
  if (coeff_ctr)
  {
    //--- set run and level (coefficient) ---
    for (se->value2=0; coeff[pos]==0; pos++, se->value2++);
    se->value1=coeff[pos++];
  }
  else
  {
    //--- set run and level (EOB) ---
    se->value1 = se->value2 = 0;
  }
  //--- decrement coefficient counter and re-set position ---
  if (coeff_ctr-- == 0) pos=0;

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\t%d\n",symbolCount++, se->tracestring, se->value1,se->value2);
  fflush(p_trace);
#endif
}
#endif 

/*!
 ************************************************************************
 * \brief
 *    arithmetic decoding
 ************************************************************************
 */
int readSyntaxElement_CABAC(SyntaxElement *se, struct img_par *img, struct inp_par *inp, DataPartition *this_dataPart)
{
  int curr_len;
  DecodingEnvironmentPtr dep_dp = &(this_dataPart->de_cabac);

  curr_len = arideco_bits_read(dep_dp);

  // perform the actual decoding by calling the appropriate method
  se->reading(se, inp, img, dep_dp);

  return (se->len = (arideco_bits_read(dep_dp) - curr_len));
}


/*!
 ************************************************************************
 * \brief
 *    decoding of unary binarization using one or 2 distinct
 *    models for the first and all remaining bins; no terminating
 *    "0" for max_symbol
 ***********************************************************************
 */
unsigned int unary_bin_max_decode(DecodingEnvironmentPtr dep_dp,
                                  BiContextTypePtr ctx,
                                  int ctx_offset,
                                  unsigned int max_symbol)
{
  unsigned int l;
  unsigned int symbol;
  BiContextTypePtr ictx;

  symbol =  biari_decode_symbol(dep_dp, ctx );

  if (symbol==0)
    return 0;
  else
  {
    if (max_symbol == 1)
    return symbol;
    symbol=0;
    ictx=ctx+ctx_offset;
    do
    {
      l=biari_decode_symbol(dep_dp, ictx);
      symbol++;
    }
    while( (l!=0) && (symbol<max_symbol-1) );
    if ((l!=0) && (symbol==max_symbol-1))
      symbol++;
    return symbol;
  }
}


/*!
 ************************************************************************
 * \brief
 *    decoding of unary binarization using one or 2 distinct
 *    models for the first and all remaining bins
 ***********************************************************************
 */
unsigned int unary_bin_decode(DecodingEnvironmentPtr dep_dp,
                              BiContextTypePtr ctx,
                              int ctx_offset)
{
  unsigned int l;
  unsigned int symbol;
  BiContextTypePtr ictx;

  symbol = biari_decode_symbol(dep_dp, ctx );

  if (symbol==0)
    return 0;
  else
  {
    symbol=0;
    ictx=ctx+ctx_offset;
    do
    {
      l=biari_decode_symbol(dep_dp, ictx);
      symbol++;
    }
    while( l!=0 );
    return symbol;
  }
}


/*!
 ************************************************************************
 * \brief
 *    finding end of a slice in case this is not the end of a frame
 *
 * Unsure whether the "correction" below actually solves an off-by-one
 * problem or whether it introduces one in some cases :-(  Anyway,
 * with this change the bit stream format works with CABAC again.
 * StW, 8.7.02
 ************************************************************************
 */
int cabac_startcode_follows(struct img_par *img, struct inp_par *inp, int eos_bit)
{
  Slice         *currSlice  = img->currentSlice;
  int           *partMap    = assignSE2partition[currSlice->dp_mode];
  DataPartition *dP;
  unsigned int  bit;
  DecodingEnvironmentPtr dep_dp;
  
  dP = &(currSlice->partArr[partMap[SE_MBTYPE]]);
  dep_dp = &(dP->de_cabac);

  if( eos_bit )
  {
    bit = biari_decode_final (dep_dp); //GB
    
#if TRACE
    //  strncpy(se->tracestring, "Decode Sliceterm", TRACESTRING_SIZE);
    fprintf(p_trace, "@%d %s\t\t%d\n",symbolCount++, "Decode Sliceterm", bit);
    fflush(p_trace);
#endif
  }
  else
  {
    bit = 0;
  }
  
  return (bit==1?1:0);
}





/*!
 ************************************************************************
 * \brief
 *    Exp Golomb binarization and decoding of a symbol
 *    with prob. of 0.5
 ************************************************************************
 */
unsigned int exp_golomb_decode_eq_prob( DecodingEnvironmentPtr dep_dp,
                                        int k)
{
  unsigned int l;
  int symbol = 0;
  int binary_symbol = 0;

  do
  {
    l=biari_decode_symbol_eq_prob(dep_dp);
    if (l==1) 
    {
      symbol += (1<<k); 
      k++;
    }
  }
  while (l!=0);

  while (k--)                             //next binary part
    if (biari_decode_symbol_eq_prob(dep_dp)==1) 
      binary_symbol |= (1<<k);

  return (unsigned int) (symbol+binary_symbol);
}


/*!
 ************************************************************************
 * \brief
 *    Exp-Golomb decoding for LEVELS
 ***********************************************************************
 */
unsigned int unary_exp_golomb_level_decode( DecodingEnvironmentPtr dep_dp,
                                            BiContextTypePtr ctx)
{
  unsigned int l,k;
  unsigned int symbol;
  unsigned int exp_start = 13;

  symbol = biari_decode_symbol(dep_dp, ctx );

  if (symbol==0)
    return 0;
  else
  {
    symbol=0;
    k=1;
    do
    {
      l=biari_decode_symbol(dep_dp, ctx);
      symbol++;
      k++;
    }
    while((l!=0) && (k!=exp_start));
    if (l!=0)
      symbol += exp_golomb_decode_eq_prob(dep_dp,0)+1;
    return symbol;
  }
}




/*!
 ************************************************************************
 * \brief
 *    Exp-Golomb decoding for Motion Vectors
 ***********************************************************************
 */
unsigned int unary_exp_golomb_mv_decode(DecodingEnvironmentPtr dep_dp,
                                        BiContextTypePtr ctx,
                                        unsigned int max_bin)
{
  unsigned int l,k;
  unsigned int bin=1;
  unsigned int symbol;
  unsigned int exp_start = 8;

  BiContextTypePtr ictx=ctx;

  symbol = biari_decode_symbol(dep_dp, ictx );

  if (symbol==0)
    return 0;
  else
  {
    symbol=0;
    k=1;

    ictx++;
    do
    {
      l=biari_decode_symbol(dep_dp, ictx  );
      if ((++bin)==2) ictx++;
      if (bin==max_bin) ictx++;
      symbol++;
      k++;
    }
    while((l!=0) && (k!=exp_start));
    if (l!=0)
      symbol += exp_golomb_decode_eq_prob(dep_dp,3)+1;
    return symbol;
  }
}


/*!
 ************************************************************************
 * \brief
 *    Read one byte from CABAC-partition. 
 *    Bitstream->read_len will be modified
 *    (for IPCM CABAC  28/11/2003)
 *
 * \author
 *    Dong Wang <[e-mail]>  
 ************************************************************************
*/
void readIPCMBytes_CABAC(SyntaxElement *sym, Bitstream *currStream)
{
  int read_len = currStream->read_len;
  int code_len = currStream->code_len;
  byte *buf = currStream->streamBuffer;
  
  sym->len=8;
  
  if(read_len<code_len)
    sym->in