image.c

H264解码器,本解码器实现了图像的264解码

        int idx = (dec_picture->ref_idx[0][ii][jj]<0)?1:0;
//        int idx = (currMB->b8mode[i]==0 && currMB->b8pdir[i]==2 ? LIST_0 : currMB->b8pdir[i]==1 ? LIST_1 : LIST_0);
//        int idx = currMB->b8pdir[i]==0 ? LIST_0 : LIST_1;
        mv                = dec_picture->mv[idx];
        pRegion->mv[0]    = (mv[ii][jj][0] + mv[ii+1][jj][0] + mv[ii][jj+1][0] + mv[ii+1][jj+1][0] + 2)/4;
        pRegion->mv[1]    = (mv[ii][jj][1] + mv[ii+1][jj][1] + mv[ii][jj+1][1] + mv[ii+1][jj+1][1] + 2)/4;
        erc_mvperMB      += mabs(pRegion->mv[0]) + mabs(pRegion->mv[1]);

        pRegion->mv[2]  = (dec_picture->ref_idx[idx][ii][jj]);
/*        
        if (currMB->b8pdir[i]==0 || (currMB->b8pdir[i]==2 && currMB->b8mode[i]!=0)) // forward or bidirect
        {
          pRegion->mv[2]  = (dec_picture->ref_idx[LIST_0][ii][jj]);
          ///???? is it right, not only "img->fw_refFrArr[jj][ii-4]"
        }
        else
        {
          pRegion->mv[2]  = (dec_picture->ref_idx[LIST_1][ii][jj]);
//          pRegion->mv[2]  = 0;
        }
        */
      }
    }
  }
}

/*!
 ************************************************************************
 * \brief
 *    set defaults for old_slice
 *    NAL unit of a picture"
 ************************************************************************
 */
void init_old_slice()
{
  old_slice.field_pic_flag = 0;

  old_slice.pps_id = INT_MAX;

  old_slice.frame_num = INT_MAX;

  old_slice.nal_ref_idc = INT_MAX;
  
  old_slice.idr_flag = 0;

  old_slice.pic_oder_cnt_lsb          = UINT_MAX;
  old_slice.delta_pic_oder_cnt_bottom = INT_MAX;

  old_slice.delta_pic_order_cnt[0] = INT_MAX;
  old_slice.delta_pic_order_cnt[1] = INT_MAX;

}

/*!
 ************************************************************************
 * \brief
 *    save slice parameters that are needed for checking of "first VCL
 *    NAL unit of a picture"
 ************************************************************************
 */
void exit_slice()
{

  old_slice.pps_id = img->currentSlice->pic_parameter_set_id;

  old_slice.frame_num = img->frame_num;

  old_slice.field_pic_flag = img->field_pic_flag;

  if(img->field_pic_flag)
  {
    old_slice.bottom_field_flag = img->bottom_field_flag;
  }

  old_slice.nal_ref_idc   = img->nal_reference_idc;
  
  old_slice.idr_flag = img->idr_flag;
  if (img->idr_flag)
  {
    old_slice.idr_pic_id = img->idr_pic_id;
  }

  if (active_sps->pic_order_cnt_type == 0)
  {
    old_slice.pic_oder_cnt_lsb          = img->pic_order_cnt_lsb;
    old_slice.delta_pic_oder_cnt_bottom = img->delta_pic_order_cnt_bottom;
  }

  if (active_sps->pic_order_cnt_type == 1)
  {
    old_slice.delta_pic_order_cnt[0] = img->delta_pic_order_cnt[0];
    old_slice.delta_pic_order_cnt[1] = img->delta_pic_order_cnt[1];
  }
}

/*!
 ************************************************************************
 * \brief
 *    detect if current slice is "first VCL NAL unit of a picture"
 ************************************************************************
 */
int is_new_picture()
{
  int result=0;

  result |= (old_slice.pps_id != img->currentSlice->pic_parameter_set_id);

  result |= (old_slice.frame_num != img->frame_num);

  result |= (old_slice.field_pic_flag != img->field_pic_flag);

  if(img->field_pic_flag && old_slice.field_pic_flag)
  {
    result |= (old_slice.bottom_field_flag != img->bottom_field_flag);
  }

  result |= (old_slice.nal_ref_idc   != img->nal_reference_idc);
  
  result |= ( old_slice.idr_flag != img->idr_flag);

  if (img->idr_flag && old_slice.idr_flag)
  {
    result |= (old_slice.idr_pic_id != img->idr_pic_id);
  }

  if (active_sps->pic_order_cnt_type == 0)
  {
    result |=  (old_slice.pic_oder_cnt_lsb          != img->pic_order_cnt_lsb);
    result |=  (old_slice.delta_pic_oder_cnt_bottom != img->delta_pic_order_cnt_bottom);
  }

  if (active_sps->pic_order_cnt_type == 1)
  {
    result |= (old_slice.delta_pic_order_cnt[0] != img->delta_pic_order_cnt[0]);
    result |= (old_slice.delta_pic_order_cnt[1] != img->delta_pic_order_cnt[1]);
  }

  return result;
}


/*!
 ************************************************************************
 * \brief
 *    decodes one slice
 ************************************************************************
 */
void decode_one_slice(struct img_par *img,struct inp_par *inp)
{

  Boolean end_of_slice = FALSE;
  int read_flag;
  img->cod_counter=-1;

  set_ref_pic_num();

  if (img->type == B_SLICE)
      compute_collocated(Co_located, listX);

  //reset_ec_flags();

  while (end_of_slice == FALSE) // loop over macroblocks
  {

#if TRACE
  fprintf(p_trace,"\n*********** POC: %i (I/P) MB: %i Slice: %i Type %d **********\n", img->ThisPOC, img->current_mb_nr, img->current_slice_nr, img->type);
#endif

    // Initializes the current macroblock
    start_macroblock(img,inp, img->current_mb_nr);
    // Get the syntax elements from the NAL
    read_flag = read_one_macroblock(img,inp);
    decode_one_macroblock(img,inp);

    if(img->MbaffFrameFlag && dec_picture->mb_field[img->current_mb_nr])
    {
      img->num_ref_idx_l0_active >>= 1;
      img->num_ref_idx_l1_active >>= 1;
    }

    ercWriteMBMODEandMV(img,inp);

    end_of_slice=exit_macroblock(img,inp,(!img->MbaffFrameFlag||img->current_mb_nr%2));
  }

  exit_slice();
  //reset_ec_flags();

}


void decode_slice(struct img_par *img,struct inp_par *inp, int current_header)
{
  Slice *currSlice = img->currentSlice;

  if (active_pps->entropy_coding_mode_flag)
  {
    init_contexts (img);
    cabac_new_slice();
  }

  if ( (active_pps->weighted_bipred_idc > 0  && (img->type == B_SLICE)) || (active_pps->weighted_pred_flag && img->type !=I_SLICE))
    fill_wp_params(img);

  //printf("frame picture %d %d %d\n",img->structure,img->ThisPOC,img->direct_type);
  

  // decode main slice information
  if ((current_header == SOP || current_header == SOS) && currSlice->ei_flag == 0)
    decode_one_slice(img,inp);
    
  // setMB-Nr in case this slice was lost
//  if(currSlice->ei_flag)  
//    img->current_mb_nr = currSlice->last_mb_nr + 1;

}


/*!
 ************************************************************************
 * \brief
 *    Prepare field and frame buffer after frame decoding
 ************************************************************************
 */
void frame_postprocessing(struct img_par *img, struct inp_par *inp)
{
}

/*!
 ************************************************************************
 * \brief
 *    Prepare field and frame buffer after field decoding
 ************************************************************************
 */
void field_postprocessing(struct img_par *img, struct inp_par *inp)
{
  img->number /= 2;
}



void reset_wp_params(struct img_par *img)
{
  int i,comp;
  int log_weight_denom;

  for (i=0; i<MAX_REFERENCE_PICTURES; i++)
  {
    for (comp=0; comp<3; comp++)
    {
      log_weight_denom = (comp == 0) ? img->luma_log2_weight_denom : img->chroma_log2_weight_denom;
      img->wp_weight[0][i][comp] = 1<<log_weight_denom;
      img->wp_weight[1][i][comp] = 1<<log_weight_denom;
    }
  }
}


void fill_wp_params(struct img_par *img)
{
  int i, j, k;
  int comp;
  int log_weight_denom;
  int p0, pt;
  int bframe = (img->type==B_SLICE);
  int max_bwd_ref, max_fwd_ref;
  int x,z;

  max_fwd_ref = img->num_ref_idx_l0_active;
  max_bwd_ref = img->num_ref_idx_l1_active;

  if (active_pps->weighted_bipred_idc == 2 && bframe)
  {
    img->luma_log2_weight_denom = 5;
    img->chroma_log2_weight_denom = 5;
    img->wp_round_luma = 16;
    img->wp_round_chroma = 16;

    for (i=0; i<MAX_REFERENCE_PICTURES; i++)
    {
      for (comp=0; comp<3; comp++)
      {
        log_weight_denom = (comp == 0) ? img->luma_log2_weight_denom : img->chroma_log2_weight_denom;
        img->wp_weight[0][i][comp] = 1<<log_weight_denom;
        img->wp_weight[1][i][comp] = 1<<log_weight_denom;
        img->wp_offset[0][i][comp] = 0;
        img->wp_offset[1][i][comp] = 0;
      }
    }
  }

  if (bframe)
  {
    for (i=0; i<max_fwd_ref; i++)
    {
      for (j=0; j<max_bwd_ref; j++)
      {
        for (comp = 0; comp<3; comp++)
        {
          log_weight_denom = (comp == 0) ? img->luma_log2_weight_denom : img->chroma_log2_weight_denom;
          if (active_pps->weighted_bipred_idc == 1)
          {
            img->wbp_weight[0][i][j][comp] =  img->wp_weight[0][i][comp];
            img->wbp_weight[1][i][j][comp] =  img->wp_weight[1][j][comp];
          }
          else if (active_pps->weighted_bipred_idc == 2)
          {
            pt = listX[LIST_1][j]->poc - listX[LIST_0][i]->poc;
            if (pt == 0 || listX[LIST_1][j]->is_long_term || listX[LIST_0][i]->is_long_term)
            {
              img->wbp_weight[0][i][j][comp] =   32;
              img->wbp_weight[1][i][j][comp] =   32;
            }
            else
            {
              p0 = img->ThisPOC - listX[LIST_0][i]->poc;
              
              x = (16384 + (pt>>1))/pt;
              z = Clip3(-1024, 1023, (x*p0 + 32 )>>6);
              
              img->wbp_weight[1][i][j][comp] = z >> 2;
              img->wbp_weight[0][i][j][comp] = 64 - img->wbp_weight[1][i][j][comp];
              if (img->wbp_weight[1][i][j][comp] < -64 || img->wbp_weight[1][i][j][comp] > 128)
              {
                img->wbp_weight[0][i][j][comp] = 32;
                img->wbp_weight[1][i][j][comp] = 32;
                img->wp_offset[0][i][comp] = 0;
                img->wp_offset[1][i][comp] = 0;
              }
            }
          }
        }
      }
    }
  }

  if (bframe && img->MbaffFrameFlag)
  {
    for (i=0; i<2*max_fwd_ref; i++)
    {
      for (j=0; j<2*max_bwd_ref; j++)
      {
        for (comp = 0; comp<3; comp++)
        {
          for (k=2; k<6; k+=2)
          {
            img->wp_offset[k+0][i][comp] = img->wp_offset[0][i/2][comp];
            img->wp_offset[k+1][i][comp] = img->wp_offset[1][i/2][comp];

            log_weight_denom = (comp == 0) ? img->luma_log2_weight_denom : img->chroma_log2_weight_denom;
            if (active_pps->weighted_bipred_idc == 1)
            {
              img->wbp_weight[k+0][i][j][comp] =  img->wp_weight[0][i/2][comp];
              img->wbp_weight[k+1][i][j][comp] =  img->wp_weight[1][j/2][comp];
            }
            else if (active_pps->weighted_bipred_idc == 2)
            {
              pt = listX[k+LIST_1][j]->poc - listX[k+LIST_0][i]->poc;
              if (pt == 0 || listX[k+LIST_1][j]->is_long_term || listX[k+LIST_0][i]->is_long_term)
              {
                img->wbp_weight[k+0][i][j][comp] =   32;
                img->wbp_weight[k+1][i][j][comp] =   32;
              }
              else
              {
                p0 = ((k==2)?img->toppoc:img->bottompoc) - listX[k+LIST_0][i]->poc;
                
                x = (16384 + (pt>>1))/pt;
                z = Clip3(-1024, 1023, (x*p0 + 32 )>>6);

                img->wbp_weight[k+1][i][j][comp] = z >> 2;
                img->wbp_weight[k+0][i][j][comp] = 64 - img->wbp_weight[k+1][i][j][comp];
                if (img->wbp_weight[k+1][i][j][comp] < -64 || img->wbp_weight[k+1][i][j][comp] > 128)
                {
                  img->wbp_weight[k+1][i][j][comp] = 32;
                  img->wbp_weight[k+0][i][j][comp] = 32;
                  img->wp_offset[k+0][i][comp] = 0;
                  img->wp_offset[k+1][i][comp] = 0;
                }
              }
            }
          }
        }
      }
    }
  }
}