macroblock.c

本源码是H.26L标准的Visual C++源代码

  //  read MB mode *****************************************************************
  currSE.type = SE_MBTYPE;
  
  if(img->type == B_IMG_1 || img->type == B_IMG_MULT)
    dP = &(currSlice->partArr[partMap[SE_BFRAME]]);
  else
    dP = &(currSlice->partArr[partMap[currSE.type]]);

  if (inp->symbol_mode == UVLC || dP->bitstream->ei_flag) 
    currSE.mapping = linfo;
  else
    currSE.reading = readMB_typeInfoFromBuffer_CABAC;

  if(inp->symbol_mode == CABAC || (img->type != INTER_IMG_1 && img->type != INTER_IMG_MULT && img->type != B_IMG_1 && img->type != B_IMG_MULT))
  {
    //  read MB mode
#if TRACE
    strncpy(currSE.tracestring, "MB Type", TRACESTRING_SIZE);
#endif
    
    dP->readSyntaxElement(&currSE,img,inp,dP);
    img->mb_mode = currMB->mb_type = currSE.value1;
  } 
  else
  {
    if(img->cod_counter == -1)
    {
#if TRACE
      strncpy(currSE.tracestring, "MB runlength", TRACESTRING_SIZE);
#endif
      dP->readSyntaxElement(&currSE,img,inp,dP);
      img->cod_counter = currSE.value1;
    }
    if (img->cod_counter==0)
    {
#if TRACE
      strncpy(currSE.tracestring, "MB Type", TRACESTRING_SIZE);
#endif
      dP->readSyntaxElement(&currSE,img,inp,dP);
      if(img->type == INTER_IMG_1 || img->type == INTER_IMG_MULT)
        currSE.value1++;
      img->mb_mode = currMB->mb_type = currSE.value1;
      img->cod_counter--;
    } 
    else
    {
      img->cod_counter--;
      img->mb_mode = 0;
    }
  }

  if(img->UseConstrainedIntraPred)
  {
    if (img->type==INTER_IMG_1 || (img->type==INTER_IMG_MULT))        // inter frame
      if (img->mb_mode < 8)
        img->intra_mb[img->current_mb_nr] = 0;
  }
  
  
  //! TO for Error Concelament
  //! If we have an INTRA Macroblock and we lost the partition
  //! which contains the intra coefficients Copy MB would be better 
  //! than just a grey block.
  //! Seems to be a bit at the wrong place to do this right here, but for this case 
  //! up to now there is no other way.
  dP = &(currSlice->partArr[partMap[SE_CBP_INTRA]]);
  if(img->mb_mode == INTRA_MB && dP->bitstream->ei_flag && img->number)
  {
    img->mb_mode = COPY_MB;
    img->imod = INTRA_MB_INTER;
  }
  if(img->type == B_IMG_1 || img->type == B_IMG_MULT)
    dP = &(currSlice->partArr[partMap[SE_BFRAME]]);
  else
    dP = &(currSlice->partArr[partMap[currSE.type]]);
  //! End TO
  
  if ((img->type==INTER_IMG_1) || (img->type==INTER_IMG_MULT))    // inter frame
    interpret_mb_mode_P(img);
  else if (img->type==INTRA_IMG)                                  // intra frame
    interpret_mb_mode_I(img);
  else if ((img->type==B_IMG_1) || (img->type==B_IMG_MULT))       // B frame
    interpret_mb_mode_B(img);
  else if ((img->type==SP_IMG_1) || (img->type==SP_IMG_MULT))    // SP frame
    interpret_mb_mode_P(img);

  if ((img->type==B_IMG_1) || (img->type==B_IMG_MULT))
    init_macroblock_Bframe(img);
  else
    init_macroblock(img);

  if (inp->symbol_mode != CABAC && img->imod==B_Direct && img->mb_mode==COPY_MB && img->cod_counter >= 0)
  {
    int i, j, iii, jjj;
    currMB->cbp = 0;
    for (i=0;i<BLOCK_SIZE;i++)
    { // reset luma coeffs
      for (j=0;j<BLOCK_SIZE;j++)
        for(iii=0;iii<BLOCK_SIZE;iii++)
          for(jjj=0;jjj<BLOCK_SIZE;jjj++)
            img->cof[i][j][iii][jjj]=0;
    }
    for (j=4;j<6;j++)
    { // reset chroma coeffs
      for (i=0;i<4;i++)
        for (iii=0;iii<4;iii++)
          for (jjj=0;jjj<4;jjj++)
            img->cof[i][j][iii][jjj]=0;
    }
    return DECODE_MB_BFRAME;
  }

  if (img->imod==INTRA_MB_INTER && img->mb_mode==COPY_MB) //keep last macroblock
  {
    return DECODE_COPY_MB;
  }

  // intra prediction modes for a macroblock 4x4 **********************************************
  if (img->imod==INTRA_MB_OLD)
  {
    currSE.type = SE_INTRAPREDMODE;
    if(img->type == B_IMG_1 || img->type == B_IMG_MULT)
      dP = &(currSlice->partArr[partMap[SE_BFRAME]]);
    else
      dP = &(currSlice->partArr[partMap[currSE.type]]);

    if (inp->symbol_mode == UVLC || dP->bitstream->ei_flag)
        currSE.mapping = linfo;
    else
        currSE.reading = readIntraPredModeFromBuffer_CABAC;

    for(i=0;i<MB_BLOCK_SIZE/2;i++)
    {
#if TRACE
      snprintf(currSE.tracestring, TRACESTRING_SIZE, "Intra mode ");
#endif

      dP->readSyntaxElement(&currSE,img,inp,dP);

      i1=img->block_x + 2*(i&0x01);
      j1=img->block_y + i/2;

      if (inp->symbol_mode == UVLC)
      {
        dbl_ipred_word = currSE.value1;
        // find intra prediction mode for two blocks
        img->ipredmode[i1+1][j1+1] = PRED_IPRED[img->ipredmode[i1+1][j1]+1][img->ipredmode[i1][j1+1]+1][IPRED_ORDER[dbl_ipred_word][0]];
        img->ipredmode[i1+2][j1+1] = PRED_IPRED[img->ipredmode[i1+2][j1]+1][img->ipredmode[i1+1][j1+1]+1][IPRED_ORDER[dbl_ipred_word][1]];
      }
      else
      {
        img->ipredmode[i1+1][j1+1] = PRED_IPRED[img->ipredmode[i1+1][j1]+1][img->ipredmode[i1][j1+1]+1][currSE.value1];
        img->ipredmode[i1+2][j1+1] = PRED_IPRED[img->ipredmode[i1+2][j1]+1][img->ipredmode[i1+1][j1+1]+1][currSE.value2];
      }
    }
  }

  // read inter frame vector data ********************************************************
  if ((img->type==B_IMG_1) || (img->type==B_IMG_MULT))
    readMotionInfoFromNAL_Bframe(img,inp);
  else if(img->imod==INTRA_MB_INTER)
    readMotionInfoFromNAL_Pframe(img,inp);

  // read CBP and Coeffs  ***************************************************************
  readCBPandCoeffsFromNAL(img,inp);

  return (((img->type==B_IMG_1) || (img->type==B_IMG_MULT)) ? DECODE_MB_BFRAME : DECODE_MB);
}

/*!
 ************************************************************************
 * \brief
 *    Get for a given MB of a P picture the reference frame
 *    parameter and the motion vectors from the NAL
 ************************************************************************
 */
void readMotionInfoFromNAL_Pframe(struct img_par *img,struct inp_par *inp)
{
  int i,j,k,l,m;
  int step_h,step_v;
  int curr_mvd;
  int mb_nr = img->current_mb_nr;
  Macroblock *currMB = &img->mb_data[mb_nr];
  SyntaxElement currSE;
  Slice *currSlice = img->currentSlice;
  DataPartition *dP;
  int *partMap = assignSE2partition[currSlice->dp_mode];
  int ref_frame = currMB->ref_frame;
  int predframe_no = currMB->predframe_no;


  // keep track of neighbouring macroblocks available for prediction
  int mb_width = img->width/16;
  int mb_available_up = (img->mb_y == 0) ? 0 : (currMB->slice_nr == img->mb_data[mb_nr-mb_width].slice_nr);
  int mb_available_left = (img->mb_x == 0) ? 0 : (currMB->slice_nr == img->mb_data[mb_nr-1].slice_nr);
  int mb_available_upleft  = (img->mb_x == 0 || img->mb_y == 0) ? 0 : (currMB->slice_nr == img->mb_data[mb_nr-mb_width-1].slice_nr);
  int mb_available_upright = (img->mb_x >= mb_width-1 || img->mb_y == 0) ? 0 : (currMB->slice_nr == img->mb_data[mb_nr-mb_width+1].slice_nr);

  // keep track of neighbouring blocks available for motion vector prediction
  int block_available_up, block_available_left, block_available_upright, block_available_upleft;
  int mv_a, mv_b, mv_c, mv_d;
  int mvPredType, rFrameL, rFrameU, rFrameUR;
  int ie, j4, i4, ii,jj;
  int pred_vec=0, vec;


  //  If multiple ref. frames, read reference frame for the MB *********************************
  if(img->type==INTER_IMG_MULT || img->type == SP_IMG_MULT)
  {
#if TRACE
    strncpy(currSE.tracestring,  "Reference frame no ", TRACESTRING_SIZE);
#endif
    currSE.type = SE_REFFRAME;
    dP = &(currSlice->partArr[partMap[currSE.type]]);

    if (inp->symbol_mode == UVLC || dP->bitstream->ei_flag)
      currSE.mapping = linfo;
    else
      currSE.reading = readRefFrameFromBuffer_CABAC;

    dP->readSyntaxElement(&currSE,img,inp,dP);
    predframe_no = currMB->predframe_no = currSE.value1;
    ref_frame = currMB->ref_frame = predframe_no;

    /*!
    * \note
    * if frame lost occurs within img->buf_cycle frames and buffer of previous
    * decoded pictures is still empty, set ref_frame to last decoded
    * picture to avoid prediction from unexistent frames.
    */
//    if (ref_frame > img->number) ref_frame = 0;

    // Update the reference frame information for motion vector prediction
    for (j = 0;j < BLOCK_SIZE;j++)
      for (i = 0;i < BLOCK_SIZE;i++)
        refFrArr[img->block_y+j][img->block_x+i] = predframe_no;
  }

  // read motion vectors **********************************************************************

  currSE.type = SE_MVD;
  dP = &(currSlice->partArr[partMap[currSE.type]]);

  if (inp->symbol_mode == UVLC || dP->bitstream->ei_flag)
    currSE.mapping = linfo_mvd;
  else
    currSE.reading = readMVDFromBuffer_CABAC;

  step_h=BLOCK_STEP[img->mb_mode][0];     // horizontal stepsize
  step_v=BLOCK_STEP[img->mb_mode][1];     // vertical stepsize

  ie=4-BLOCK_STEP[img->mb_mode][0];
  for (j=0; j < BLOCK_SIZE; j += step_v)
  {
    block_available_up = mb_available_up || (j > 0);
    j4=img->block_y+j;

    for (i=0;i < BLOCK_SIZE; i += step_h)
    {
      i4=img->block_x+i;
      // first make mv-prediction

      // D B C
      // A X

      // 1 A, B, D are set to 0 if unavailable
      // 2 If C is not available it is replaced by D

      block_available_left = mb_available_left || (i > 0);

      if (j > 0)
        block_available_upright = i != ie ? 1 : 0;
      else if (i != ie)
        block_available_upright = block_available_up;
      else
        block_available_upright = mb_available_upright;

      if (i > 0)
        block_available_upleft = j > 0 ? 1 : block_available_up;
      else if (j > 0)
        block_available_upleft = block_available_left;
      else
        block_available_upleft = mb_available_upleft;

      mvPredType = MVPRED_MEDIAN;

      rFrameL    = block_available_left    ? refFrArr[j4][i4-1]   : -1;
      rFrameU    = block_available_up      ? refFrArr[j4-1][i4]   : -1;
      rFrameUR   = block_available_upright ? refFrArr[j4-1][i4+BLOCK_STEP[img->mb_mode][0]] :
      block_available_upleft  ? refFrArr[j4-1][i4-1] : -1;

      // Prediction if only one of the neighbors uses the selected reference frame

      if(rFrameL == predframe_no && rFrameU != predframe_no && rFrameUR != predframe_no)
        mvPredType = MVPRED_L;
      else if(rFrameL != predframe_no && rFrameU == predframe_no && rFrameUR != predframe_no)
        mvPredType = MVPRED_U;
      else if(rFrameL != predframe_no && rFrameU != predframe_no && rFrameUR == predframe_no)
        mvPredType = MVPRED_UR;

      // Directional predictions

      else if(img->mb_mode == 3)
      {
        if(i == 0)
        {
          if(rFrameL == predframe_no)
            mvPredType = MVPRED_L;
        }
        else
        {
          if(rFrameUR == predframe_no)
            mvPredType = MVPRED_UR;
        }
      }
      else if(img->mb_mode == 2)
      {
        if(j == 0)
        {
          if(rFrameU == predframe_no)
            mvPredType = MVPRED_U;
        }
        else
        {
          if(rFrameL == predframe_no)
            mvPredType = MVPRED_L;
        }
      }
      else if(img->mb_mode == 5 && i == 2)
        mvPredType = MVPRED_L;
      else if(img->mb_mode == 6 && j == 2)
        mvPredType = MVPRED_U;

      for (k=0; k < 2; k++)
      {

        mv_a = block_available_left ? img->mv[i4-1+BLOCK_SIZE][j4][k] : 0;
        mv_b = block_available_up      ? img->mv[i4+BLOCK_SIZE][j4-1][k]   : 0;
        mv_d = block_available_upleft  ? img->mv[i4-1+BLOCK_SIZE][j4-1][k] : 0;
        mv_c = block_available_upright ? img->mv[i4+BLOCK_STEP[img->mb_mode][0]+BLOCK_SIZE][j4-1][k] : mv_d;

        switch (mvPredType)
        {
        case MVPRED_MEDIAN:
          if(!(block_available_upleft || block_available_up || block_available_upright))
            pred_vec = mv_a;
          else
            pred_vec =mv_a+mv_b+mv_c-min(mv_a,min(mv_b,mv_c))-max(mv_a,max(mv_b,mv_c));
          break;
        case MVPRED_L:
          pred_vec = mv_a;
          break;
        case MVPRED_U:
          pred_vec = mv_b;
          break;
        case MVPRED_UR:
          pred_vec = mv_c;
          break;
        default:
          break;
        }
#if TRACE
        snprintf(currSE.tracestring, TRACESTRING_SIZE, " MVD");
#endif
        img->subblock_x = i; // position used for context determination
        img->subblock_y = j; // position used for context determination
        currSE.value2 = k; // identifies the component; only used for context determination

        dP->readSyntaxElement(&currSE,img,inp,dP);
        curr_mvd = currSE.value1;

        vec=curr_mvd+pred_vec;           // find motion vector
        for(ii=0;ii<BLOCK_STEP[img->mb_mode][0];ii++)
          for(jj=0;jj<BLOCK_STEP[img->mb_mode][1];jj++)
            img->mv[i4+ii+BLOCK_SIZE][j4+jj][k]=vec;

          // store (oversampled) mvd
          for (l=0; l < step_v; l++)
            for (m=0; m < step_h; m++)
              currMB->mvd[0][j+l][i+m][k] =  curr_mvd;
      }
    }
  }
}

/*!
 ************************************************************************
 * \brief
 *    Get coded block pattern and coefficients (run/level)
 *    from the NAL
 ************************************************************************