cabac.c

本源码是H.26L标准的Visual C++源代码

  for (j=0; j < NUM_TRANS_TYPE; j++)
  {
    if (enco_ctx->level_context[j] != NULL)
      free(enco_ctx->level_context[j]);

    if (enco_ctx->run_context[j] != NULL)
      free(enco_ctx->run_context[j]);
  }
  free( enco_ctx );

  return;

}

/*!
 **************************************************************************
 * \brief
 *    generates arithmetic code and passes the code to the buffer
 **************************************************************************
 */
int writeSyntaxElement_CABAC(SyntaxElement *se, DataPartition *this_dataPart)
{
  int curr_len;
  EncodingEnvironmentPtr eep_dp = &(this_dataPart->ee_cabac);

  curr_len = arienco_bits_written(eep_dp);

  // perform the actual coding by calling the appropriate method
  se->writing(se, eep_dp);

  if(se->type != SE_HEADER)
    this_dataPart->bitstream->write_flag = 1;

  return (se->len = (arienco_bits_written(eep_dp) - curr_len));
}

/*!
 ***************************************************************************
 * \brief
 *    This function is used to arithmetically encode the macroblock
 *    type info of a given MB.
 ***************************************************************************
 */
void writeMB_typeInfo2Buffer_CABAC(SyntaxElement *se, EncodingEnvironmentPtr eep_dp)
{
  int l;
  int a, b;
  int act_ctx;
  int act_sym;
  int log_sym;
  int mode_sym=0;
  int mask;
  int mode16x16;

  MotionInfoContexts *ctx = (img->currentSlice)->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];
  int curr_mb_type = se->value1;

  if(img->type == INTRA_IMG)  // INTRA-frame
  {
    if (currMB->mb_available[0][1] == NULL)
      b = 0;
    else
      b = (( (currMB->mb_available[0][1])->mb_type != 0) ? 1 : 0 );
    if (currMB->mb_available[1][0] == NULL)
      a = 0;
    else
      a = (( (currMB->mb_available[1][0])->mb_type != 0) ? 1 : 0 );

    act_ctx = a + b;
    act_sym = curr_mb_type;
    se->context = act_ctx; // store context

    if (act_sym==0) // 4x4 Intra
      biari_encode_symbol(eep_dp, 0, ctx->mb_type_contexts[0] + act_ctx );
    else // 16x16 Intra
    {
      biari_encode_symbol(eep_dp, 1, ctx->mb_type_contexts[0] + act_ctx );
      mode_sym=act_sym-1; // Values in the range of 0...23
      act_ctx = 4;
      act_sym = mode_sym/12;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[0] + act_ctx ); // coding of AC/no AC
      mode_sym = mode_sym % 12;
      act_sym = mode_sym / 4; // coding of cbp: 0,1,2
      act_ctx = 5;
      if (act_sym==0)
      {
        biari_encode_symbol(eep_dp, 0, ctx->mb_type_contexts[0] + act_ctx );
      }
      else
      {
        biari_encode_symbol(eep_dp, 1, ctx->mb_type_contexts[0] + act_ctx );
        act_ctx=6;
        if (act_sym==1)
        {
          biari_encode_symbol(eep_dp, 0, ctx->mb_type_contexts[0] + act_ctx );
        }
        else
        {

          biari_encode_symbol(eep_dp, 1, ctx->mb_type_contexts[0] + act_ctx );
        }

      }
      mode_sym = mode_sym % 4; // coding of I pred-mode: 0,1,2,3
      act_sym = mode_sym/2;
      act_ctx = 7;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[0] + act_ctx );
      act_ctx = 8;
      act_sym = mode_sym%2;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[0] + act_ctx );
    }
  }
  else
  {

    if (currMB->mb_available[0][1] == NULL)
      b = 0;
    else
      b = (( (currMB->mb_available[0][1])->mb_type != 0) ? 1 : 0 );
    if (currMB->mb_available[1][0] == NULL)
      a = 0;
    else
      a = (( (currMB->mb_available[1][0])->mb_type != 0) ? 1 : 0 );


    act_sym = curr_mb_type;

    if(act_sym>=(mode16x16=(8*img->type+1))) // 16x16 Intra-mode: mode16x16=9 (P-frame) mode16x16=17 (B-frame)
    {
      mode_sym=act_sym-mode16x16;
      act_sym=mode16x16; // 16x16 mode info
    }

    act_sym++;

    for (log_sym = 0; (1<<log_sym) <= act_sym; log_sym++);
    log_sym--;

    act_ctx = a + b;
    se->context = act_ctx; // store context

    if (log_sym==0)
    {
      biari_encode_symbol(eep_dp, 0, &ctx->mb_type_contexts[1][act_ctx] );

    }
    else
    {
      // code unary part
      biari_encode_symbol(eep_dp, 1, &ctx->mb_type_contexts[1][act_ctx] );
      act_ctx=4;
      if (log_sym==1)
      {
        biari_encode_symbol(eep_dp, 0, &ctx->mb_type_contexts[1][act_ctx ] );
      }
      else
      {
        for(l=0;l<log_sym-1;l++)
        {
          biari_encode_symbol(eep_dp, 1, &ctx->mb_type_contexts[1][act_ctx] );
          if (l==0) act_ctx=5;
        }
        if ( log_sym < (3+((img->type == B_IMG)?1:0)) ) // maximum mode no. is 9 (P-frame) or 17 (B-frame)
          biari_encode_symbol(eep_dp, 0, &ctx->mb_type_contexts[1][act_ctx ] );
      }

      // code binary part
      act_ctx=6;
      if (log_sym==(3+((img->type == B_IMG)?1:0)) ) log_sym=2; // only 2 LSBs are actually set for mode 7-9 (P-frame) or 15-17 (B-frame)
      mask = (1<<log_sym); // MSB
      for(l=0;l<log_sym;l++)
      {
        mask >>=1;
        biari_encode_symbol(eep_dp, (unsigned char) (act_sym & mask), &ctx->mb_type_contexts[1][act_ctx] );
      }
    }


    if(act_sym==(mode16x16+1)) // additional info for 16x16 Intra-mode
    {
      act_ctx = 7;
      act_sym = mode_sym/12;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[1] + act_ctx ); // coding of AC/no AC
      mode_sym = mode_sym % 12;

      act_sym = mode_sym / 4; // coding of cbp: 0,1,2
      act_ctx = 8;
      if (act_sym==0)
      {
        biari_encode_symbol(eep_dp, 0, ctx->mb_type_contexts[1] + act_ctx );
      }
      else
      {
        biari_encode_symbol(eep_dp, 1, ctx->mb_type_contexts[1] + act_ctx );
        if (act_sym==1)
        {
          biari_encode_symbol(eep_dp, 0, ctx->mb_type_contexts[1] + act_ctx );
        }
        else
        {

          biari_encode_symbol(eep_dp, 1, ctx->mb_type_contexts[1] + act_ctx );
        }

      }

      mode_sym = mode_sym % 4; // coding of I pred-mode: 0,1,2,3
      act_ctx = 9;

      act_sym = mode_sym/2;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[1] + act_ctx );
      act_sym = mode_sym%2;
      biari_encode_symbol(eep_dp, (unsigned char) act_sym, ctx->mb_type_contexts[1] + act_ctx );

    }
  }
}

/*!
 ****************************************************************************
 * \brief
 *    This function is used to arithmetically encode a pair of
 *    intra prediction modes of a given MB.
 ****************************************************************************
 */

void writeIntraPredMode2Buffer_CABAC(SyntaxElement *se, EncodingEnvironmentPtr eep_dp)
{
  static int prev_sym = 0;
  static int count = 0; // to detect a new row of intra prediction modes

  TextureInfoContexts *ctx = img->currentSlice->tex_ctx;

  if (count % 2 == 0)
    prev_sym = 0;

  unary_bin_max_encode(eep_dp,(unsigned int) se->value1,ctx->ipr_contexts[prev_sym],1,5);
  prev_sym = se->value1;
  unary_bin_max_encode(eep_dp,(unsigned int) se->value2,ctx->ipr_contexts[prev_sym],1,5);
  prev_sym = se->value2;


  if(++count == MB_BLOCK_SIZE/2) // all modes of one MB have been processed
    count=0;
}

/*!
 ****************************************************************************
 * \brief
 *    This function is used to arithmetically encode the reference
 *    parameter of a given MB.
 ****************************************************************************
 */
void writeRefFrame2Buffer_CABAC(SyntaxElement *se, EncodingEnvironmentPtr eep_dp)
{
  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  int a, b;
  int act_ctx;
  int act_sym;

  if (currMB->mb_available[0][1] == NULL)
    b = 0;
  else
    b = ( ((currMB->mb_available[0][1])->ref_frame != 0) ? 1 : 0);
  if (currMB->mb_available[1][0] == NULL)
    a = 0;
  else
    a = ( ((currMB->mb_available[1][0])->ref_frame != 0) ? 1 : 0);

  act_ctx = a + 2*b;
  se->context = act_ctx; // store context
  act_sym = se->value1;

  if (act_sym==0)
  {
    biari_encode_symbol(eep_dp, 0, ctx->ref_no_contexts + act_ctx );
  }
  else
  {
    biari_encode_symbol(eep_dp, 1, ctx->ref_no_contexts + act_ctx);
    act_sym--;
    act_ctx=4;
    unary_bin_encode(eep_dp, act_sym,ctx->ref_no_contexts+act_ctx,1);
  }
}

/*!
 ****************************************************************************
 * \brief
 *    This function is used to arithmetically encode the motion
 *    vector data of a given MB.
 ****************************************************************************
 */
void writeMVD2Buffer_CABAC(SyntaxElement *se, EncodingEnvironmentPtr eep_dp)
{
  int step_h, step_v;
  int i = img->subblock_x;
  int j = img->subblock_y;
  int a, b;
  int act_ctx;
  int act_sym;
  int mv_pred_res;
  int mv_local_err;
  int mv_sign;
  int k = se->value2; // MVD component

  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];
  int curr_mb_type = currMB->mb_type;


  step_h=input->blc_size[curr_mb_type][0]/BLOCK_SIZE;
  step_v=input->blc_size[curr_mb_type][1]/BLOCK_SIZE;

  if (j==0)
  {
    if (currMB->mb_available[0][1] == NULL)
      b = 0;
    else
      b = absm((currMB->mb_available[0][1])->mvd[0][BLOCK_SIZE-1][i][k]);
  }
  else
    b = absm(currMB->mvd[0][j-step_v][i][k]);

  if (i==0)
  {
    if (currMB->mb_available[1][0] == NULL)
      a = 0;
    else
      a = absm((currMB->mb_available[1][0])->mvd[0][j][BLOCK_SIZE-1][k]);
  }
  else
    a = absm(currMB->mvd[0][j][i-step_h][k]);

  if ((mv_local_err=a+b)<3)
    act_ctx = 5*k;
  else
  {
    if (mv_local_err>32)
      act_ctx=5*k+3;
    else
      act_ctx=5*k+2;
  }
  mv_pred_res = se->value1;
  se->context = act_ctx;

  act_sym = absm(mv_pred_res);

 if (act_sym == 0)
    biari_encode_symbol(eep_dp, 0, &ctx->mv_res_contexts[0][act_ctx] );
  else
  {
    biari_encode_symbol(eep_dp, 1, &ctx->mv_res_contexts[0][act_ctx] );
    act_sym--;
    act_ctx=5*k;
    unary_mv_encode(eep_dp,act_sym,ctx->mv_res_contexts[1]+act_ctx,3);

    mv_sign = (mv_pred_res<0) ? 1: 0;
    act_ctx=5*k+4;
    biari_encode_symbol(eep_dp, (unsigned char) mv_sign, &ctx->mv_res_contexts[1][act_ctx] );
 
  }
}
/*!
 ****************************************************************************
 * \brief
 *    This function is used to arithmetically encode the coded
 *    block pattern of a given delta quant.
 ****************************************************************************
 */
void writeDquant_CABAC(SyntaxElement *se, EncodingEnvironmentPtr eep_dp)
{
  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  int act_ctx;
  int act_sym;
  int dquant = se->value1;
  int sign=0;

  if (dquant <= 0)
    sign = 1;
  act_sym = abs(dquant) << 1;

  act_sym += sign;
  act_sym --;

  if (currMB->mb_available[1][0] == NULL)