cabac.c

H.264视频编解码的标准测试模型

  int bframe=(img->type==B_SLICE);
  MotionInfoContexts *ctx = (img->currentSlice)->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];


  if (bframe)
  {
    if (currMB->mb_available_up == NULL)
      b = 0;
    else
      b = (currMB->mb_available_up->skip_flag==0 ? 1 : 0);
    if (currMB->mb_available_left == NULL)
      a = 0;
    else
      a = (currMB->mb_available_left->skip_flag==0 ? 1 : 0);
    
    act_ctx = 7 + a + b;
    
    if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][act_ctx]) == 1)
      se->value1 = se->value2 = 0;
    else
      se->value1 = se->value2 = 1;
  }
  else
  {
    if (currMB->mb_available_up == NULL)
      b = 0;
    else
      b = (( (currMB->mb_available_up)->skip_flag == 0) ? 1 : 0 );
    if (currMB->mb_available_left == NULL)
      a = 0;
    else
      a = (( (currMB->mb_available_left)->skip_flag == 0) ? 1 : 0 );

    act_ctx = a + b;

    if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][act_ctx]) == 1)
      se->value1 = 0;
    else
      se->value1 = 1;
  }


#if TRACE
  fprintf(p_trace, "@%d %s\t\t%d\t%d %d\n",symbolCount++, se->tracestring, se->value1,a,b);
  fflush(p_trace);
#endif
  if (!se->value1)
  {
    last_dquant=0;
  }
  return;
}

/*!
***************************************************************************
* \brief
*    This function is used to arithmetically decode the macroblock
*    intra_pred_size flag info of a given MB.
***************************************************************************
*/

void readMB_transform_size_flag_CABAC( SyntaxElement *se,
                                  struct inp_par *inp,
                                  struct img_par *img,
                                  DecodingEnvironmentPtr dep_dp)
{
  int a, b;
  int act_ctx = 0;
  int act_sym;
  
  MotionInfoContexts *ctx         = (img->currentSlice)->mot_ctx;
  Macroblock         *currMB      = &img->mb_data[img->current_mb_nr];
  
  if (currMB->mb_available_up == NULL)
    b = 0;
  else 
    b = currMB->mb_available_up->luma_transform_size_8x8_flag;
  
  if (currMB->mb_available_left == NULL)
    a = 0;
  else 
    a = currMB->mb_available_left->luma_transform_size_8x8_flag;
  
  act_ctx     = a + b;
  
  
  act_sym = biari_decode_symbol(dep_dp, ctx->transform_size_contexts + act_ctx );
  se->value1 = act_sym;
  
#if TRACE
  fprintf(p_trace, "@%d %s\t\t%d\t%d %d\n",symbolCount++, se->tracestring, se->value1,a,b);
  fflush(p_trace);
#endif
  
}

/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode the macroblock
 *    type info of a given MB.
 ************************************************************************
 */
void readMB_typeInfo_CABAC( SyntaxElement *se,
                            struct inp_par *inp,
                            struct img_par *img,
                            DecodingEnvironmentPtr dep_dp)
{
  int a, b;
  int act_ctx;
  int act_sym;
  int bframe=(img->type==B_SLICE);
  int mode_sym;
  int ct = 0;
  int curr_mb_type;


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

  if(img->type == I_SLICE)  // INTRA-frame
  {
    if (currMB->mb_available_up == NULL)
      b = 0;
    else 
      b = (((currMB->mb_available_up)->mb_type != I4MB && currMB->mb_available_up->mb_type != I8MB) ? 1 : 0 );

    if (currMB->mb_available_left == NULL)
      a = 0;
    else 
      a = (((currMB->mb_available_left)->mb_type != I4MB && currMB->mb_available_left->mb_type != I8MB) ? 1 : 0 );
      
    act_ctx = a + b;
    act_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx);
    se->context = act_ctx; // store context

    if (act_sym==0) // 4x4 Intra
    {
      curr_mb_type = act_sym;
    }
    else // 16x16 Intra
    {
      mode_sym = biari_decode_final(dep_dp);
      if(mode_sym == 1)
      {
        curr_mb_type = 25;
      }
      else
      {
        act_sym = 1;
        act_ctx = 4;
        mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx ); // decoding of AC/no AC
        act_sym += mode_sym*12;
        act_ctx = 5;
        // decoding of cbp: 0,1,2
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
        if (mode_sym!=0)
        {
          act_ctx=6;
          mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          act_sym+=4;
          if (mode_sym!=0)
              act_sym+=4;
            }
          // decoding of I pred-mode: 0,1,2,3
          act_ctx = 7;
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          act_sym += mode_sym*2;
          act_ctx = 8;
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          act_sym += mode_sym;
          curr_mb_type = act_sym;
      }
    }
  }
  else if(img->type == SI_SLICE)  // SI-frame
  {
    // special ctx's for SI4MB
    if (currMB->mb_available_up == NULL)
      b = 0;
    else 
      b = (( (currMB->mb_available_up)->mb_type != SI4MB) ? 1 : 0 );
    if (currMB->mb_available_left == NULL)
      a = 0;
    else 
      a = (( (currMB->mb_available_left)->mb_type != SI4MB) ? 1 : 0 );

    act_ctx = a + b;
    act_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx);
    se->context = act_ctx; // store context

    if (act_sym==0) //  SI 4x4 Intra
    {
      curr_mb_type = 0;
    }
    else // analog INTRA_IMG
    {
      if (currMB->mb_available_up == NULL)
        b = 0;
      else 
        b = (( (currMB->mb_available_up)->mb_type != I4MB) ? 1 : 0 );
      if (currMB->mb_available_left == NULL)
        a = 0;
      else 
        a = (( (currMB->mb_available_left)->mb_type != I4MB) ? 1 : 0 );

      act_ctx = a + b;
      act_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx);
      se->context = act_ctx; // store context
      
      
      if (act_sym==0) // 4x4 Intra
      {
        curr_mb_type = 1;
      }
      else // 16x16 Intra
      {
        mode_sym = biari_decode_final(dep_dp);
        if( mode_sym==1 )
        {
          curr_mb_type = 26;
        }
        else
        {
          act_sym = 2;
          act_ctx = 4;
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx ); // decoding of AC/no AC
          act_sym += mode_sym*12;
          act_ctx = 5;
          // decoding of cbp: 0,1,2
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          if (mode_sym!=0)
          {
            act_ctx=6;
            mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
            act_sym+=4;
            if (mode_sym!=0)
              act_sym+=4;
          }
          // decoding of I pred-mode: 0,1,2,3
          act_ctx = 7;
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          act_sym += mode_sym*2;
          act_ctx = 8;
          mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[0] + act_ctx );
          act_sym += mode_sym;
          curr_mb_type = act_sym;
        }
      }
    }
  }
  else
  {
    if (bframe)
    {
      ct = 1;
      if (currMB->mb_available_up == NULL)
        b = 0;
      else
        b = (( (currMB->mb_available_up)->mb_type != 0) ? 1 : 0 );
      if (currMB->mb_available_left == NULL)
        a = 0;
      else
        a = (( (currMB->mb_available_left)->mb_type != 0) ? 1 : 0 );

      act_ctx = a + b;

      if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][act_ctx]))
      {
        if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][4]))
        {
          if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][5]))
          {
            act_sym=12;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=8;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=4;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=2;

            if      (act_sym==24)  act_sym=11;
            else if (act_sym==26)  act_sym=22;
            else
            {
              if (act_sym==22)     act_sym=23;
              if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=1; 
            }
          }
          else
          {
            act_sym=3;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=4;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=2;
            if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym+=1;
          }
        }
        else
        {
          if (biari_decode_symbol (dep_dp, &ctx->mb_type_contexts[2][6])) act_sym=2;
          else                                                            act_sym=1;
        }
      }
      else
      {
        act_sym = 0;
      }
    }
    else // P-frame
    {
      {
        if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][4] )) 
        {
          if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][7] ))   act_sym = 7;
          else                                                              act_sym = 6;
        }
        else
        {
          if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][5] ))
          {
            if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][7] )) act_sym = 2;
            else                                                            act_sym = 3;
          }
          else
          {
            if (biari_decode_symbol(dep_dp, &ctx->mb_type_contexts[1][6] )) act_sym = 4;
            else                                                            act_sym = 1;
          }
        }
      }
    }

    if (act_sym<=6 || (((img->type == B_SLICE)?1:0) && act_sym<=23))
    {
      curr_mb_type = act_sym;
    }
    else  // additional info for 16x16 Intra-mode
    {
      mode_sym = biari_decode_final(dep_dp);
      if( mode_sym==1 )
      {
        if(bframe)  // B frame
          curr_mb_type = 48;
        else      // P frame
          curr_mb_type = 31;
      }
      else
      {
        act_ctx = 8;
        mode_sym =  biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx ); // decoding of AC/no AC
        act_sym += mode_sym*12;

        // decoding of cbp: 0,1,2
        act_ctx = 9;
        mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx );
        if (mode_sym != 0)
        {
          act_sym+=4;
          mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx );
          if (mode_sym != 0)
            act_sym+=4;
        }

        // decoding of I pred-mode: 0,1,2,3
        act_ctx = 10;
        mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx );
        act_sym += mode_sym*2;
        mode_sym = biari_decode_symbol(dep_dp, ctx->mb_type_contexts[1] + act_ctx );
        act_sym += mode_sym;
        curr_mb_type = act_sym;
      }
    }
  }
  se->value1 = curr_mb_type;

//  if (curr_mb_type >= 23)       printf(" stopx");
#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\n",symbolCount++, se->tracestring, se->value1);
  fflush(p_trace);
#endif
}

/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode a pair of
 *    intra prediction modes of a given MB.
 ************************************************************************
 */
void readIntraPredMode_CABAC( SyntaxElement *se,
                              struct inp_par *inp,
                              struct img_par *img,
                              DecodingEnvironmentPtr dep_dp)
{
  TextureInfoContexts *ctx     = img->currentSlice->tex_ctx;
  int act_sym;

  // use_most_probable_mode
  act_sym = biari_decode_symbol(dep_dp, ctx->ipr_contexts);

  // remaining_mode_selector
  if (act_sym == 1)
    se->value1 = -1;
  else
  {
    se->value1  = 0;
    se->value1 |= (biari_decode_symbol(dep_dp, ctx->ipr_contexts+1)     );
    se->value1 |= (biari_decode_symbol(dep_dp, ctx->ipr_contexts+1) << 1);
    se->value1 |= (biari_decode_symbol(dep_dp, ctx->ipr_contexts+1) << 2);
  }

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\n",symbolCount++, se->tracestring, se->value1);
  fflush(p_trace);
#endif
}
/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode the reference
 *    parameter of a given MB.
 ************************************************************************
 */
void readRefFrame_CABAC( SyntaxElement *se,
                         struct inp_par *inp,
                         struct img_par *img,
                         DecodingEnvironmentPtr dep_dp)
{
  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  int   addctx  = 0;
  int   a, b;
  int   act_ctx;
  int   act_sym;
  char** refframe_array = dec_picture->ref_idx[se->value2];
  int   b8a, b8b;

  PixelPos block_a, block_b;
  
  getLuma4x4Neighbour(img->current_mb_nr, img->subblock_x, img->subblock_y, -1,  0, &block_a);
  getLuma4x4Neighbour(img->current_mb_nr, img->subblock_x, img->subblock_y,  0, -1, &block_b);

  b8a=((block_a.x/2)%2)+2*((block_a.y/2)%2);
  b8b=((block_b.x/2)%2)+2*((block_b.y/2)%2);

  if (!block_b.available)
    b=0;
  else if ( (img->mb_data[block_b.mb_addr].mb_type==IPCM) || IS_DIRECT(&img->mb_data[block_b.mb_addr]) || (img->mb_data[block_b.mb_addr].b8mode[b8b]==0 && img->mb_data[block_b.mb_addr].b8pdir[b8b]==2))
    b=0;
  else 
  {
    if (img->MbaffFrameFlag && (currMB->mb_field == 0) && (img->mb_data[block_b.mb_addr].mb_field == 1))