image.c

H264解码器,本解码器实现了图像的264解码

          for (result = 0, x = -2; x < 4; x++)
            result += list[ref_frame]->imgY[pres_y][max(0,min(maxold_x,x_pos+i+x))]*COEF[x+2];
          block[i][j] = max(0, min(255, (result+16)/32));
        }
      }

      for (j = 0; j < BLOCK_SIZE; j++) {
        for (i = 0; i < BLOCK_SIZE; i++) {
          pres_x = dx == 1 ? x_pos+i : x_pos+i+1;
          pres_x = max(0,min(maxold_x,pres_x));
          for (result = 0, y = -2; y < 4; y++)
            result += list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j+y))][pres_x]*COEF[y+2];
          block[i][j] = (block[i][j] + max(0, min(255, (result+16)/32)) +1 ) / 2;
        }
      }

    }
  }

}


void reorder_lists(int currSliceType, Slice * currSlice)
{

  if ((currSliceType != I_SLICE)&&(currSliceType != SI_SLICE))
  {
    if (currSlice->ref_pic_list_reordering_flag_l0)
    {
      reorder_ref_pic_list(listX[0], &listXsize[0], 
                           img->num_ref_idx_l0_active - 1, 
                           currSlice->remapping_of_pic_nums_idc_l0, 
                           currSlice->abs_diff_pic_num_minus1_l0, 
                           currSlice->long_term_pic_idx_l0);
    }
    if (NULL == listX[0][img->num_ref_idx_l0_active-1])
    {
      error("number of entries in list 0 smaller than num_ref_idx_l0_active_minus1",500);
    }
    // that's a definition
    listXsize[0] = img->num_ref_idx_l0_active;
  }
  if (currSliceType == B_SLICE)
  {
    if (currSlice->ref_pic_list_reordering_flag_l1)
    {
      reorder_ref_pic_list(listX[1], &listXsize[1], 
                           img->num_ref_idx_l1_active - 1, 
                           currSlice->remapping_of_pic_nums_idc_l1, 
                           currSlice->abs_diff_pic_num_minus1_l1, 
                           currSlice->long_term_pic_idx_l1);
    }
    if (NULL == listX[1][img->num_ref_idx_l1_active-1])
    {
      error("number of entries in list 1 smaller than num_ref_idx_l1_active_minus1",500);
    }
    // that's a definition
    listXsize[1] = img->num_ref_idx_l1_active;
  }

  free_ref_pic_list_reordering_buffer(currSlice);
}


/*!
 ************************************************************************
 * \brief
 *    initialize ref_pic_num array
 ************************************************************************
 */
void set_ref_pic_num()
{
  int i,j;
  
  int slice_id=img->current_slice_nr;

  for (i=0;i<listXsize[LIST_0];i++)
  {
    dec_picture->ref_pic_num        [slice_id][LIST_0][i]=listX[LIST_0][i]->poc * 2 + ((listX[LIST_0][i]->structure==BOTTOM_FIELD)?1:0) ; 
    dec_picture->frm_ref_pic_num    [slice_id][LIST_0][i]=listX[LIST_0][i]->frame_poc * 2; 
    dec_picture->top_ref_pic_num    [slice_id][LIST_0][i]=listX[LIST_0][i]->top_poc * 2; 
    dec_picture->bottom_ref_pic_num [slice_id][LIST_0][i]=listX[LIST_0][i]->bottom_poc * 2 + 1; 
    //printf("POCS %d %d %d %d ",listX[LIST_0][i]->frame_poc,listX[LIST_0][i]->bottom_poc,listX[LIST_0][i]->top_poc,listX[LIST_0][i]->poc);
    //printf("refid %d %d %d %d\n",(int) dec_picture->frm_ref_pic_num[LIST_0][i],(int) dec_picture->top_ref_pic_num[LIST_0][i],(int) dec_picture->bottom_ref_pic_num[LIST_0][i],(int) dec_picture->ref_pic_num[LIST_0][i]);
  }

  for (i=0;i<listXsize[LIST_1];i++)
  {
    dec_picture->ref_pic_num        [slice_id][LIST_1][i]=listX[LIST_1][i]->poc  *2 + ((listX[LIST_1][i]->structure==BOTTOM_FIELD)?1:0);
    dec_picture->frm_ref_pic_num    [slice_id][LIST_1][i]=listX[LIST_1][i]->frame_poc * 2; 
    dec_picture->top_ref_pic_num    [slice_id][LIST_1][i]=listX[LIST_1][i]->top_poc * 2; 
    dec_picture->bottom_ref_pic_num [slice_id][LIST_1][i]=listX[LIST_1][i]->bottom_poc * 2 + 1; 
  }

  if (img->structure==FRAME)
    for (j=2;j<6;j++)
      for (i=0;i<listXsize[j];i++)
      {    
        dec_picture->ref_pic_num        [slice_id][j][i] = listX[j][i]->poc * 2 + ((listX[j][i]->structure==BOTTOM_FIELD)?1:0);
        dec_picture->frm_ref_pic_num    [slice_id][j][i] = listX[j][i]->frame_poc * 2 ;
        dec_picture->top_ref_pic_num    [slice_id][j][i] = listX[j][i]->top_poc * 2 ;
        dec_picture->bottom_ref_pic_num [slice_id][j][i] = listX[j][i]->bottom_poc * 2 + 1;
      }

}


/*!
 ************************************************************************
 * \brief
 *    Reads new slice from bit_stream
 ************************************************************************
 */
int read_new_slice()
{
  NALU_t *nalu = AllocNALU(MAX_CODED_FRAME_SIZE);
  int current_header;
  int ret;
  int BitsUsedByHeader;
  Slice *currSlice = img->currentSlice;
  Bitstream *currStream;

  int slice_id_a, slice_id_b, slice_id_c;
  int redundant_pic_cnt_b, redundant_pic_cnt_c;
  long ftell_position, expected_slice_type;
  
//  int i;
  expected_slice_type = NALU_TYPE_DPA;

  while (1)
  {
    ftell_position = ftell(bits);

    if (input->FileFormat == PAR_OF_ANNEXB)
      ret=GetAnnexbNALU (nalu);
    else
      ret=GetRTPNALU (nalu);

    //In some cases, zero_byte shall be present. If current NALU is a VCL NALU, we can't tell
    //whether it is the first VCL NALU at this point, so only non-VCL NAL unit is checked here.
    CheckZeroByteNonVCL(nalu, &ret);

    NALUtoRBSP(nalu);
//    printf ("nalu->len %d\n", nalu->len);
    
    if (ret < 0)
      printf ("Error while getting the NALU in file format %s, exit\n", input->FileFormat==PAR_OF_ANNEXB?"Annex B":"RTP");
    if (ret == 0)
    {
//      printf ("read_new_slice: returning %s\n", "EOS");
      if(expected_slice_type != NALU_TYPE_DPA)
      {
        /* oops... we found the next slice, go back! */
        fseek(bits, ftell_position, SEEK_SET);
        FreeNALU(nalu);
        return current_header;
      }
      else
        return EOS;
    }

    // Got a NALU
    if (nalu->forbidden_bit)
    {
      printf ("Found NALU w/ forbidden_bit set, bit error?  Let's try...\n");
    }

    switch (nalu->nal_unit_type)
    {
      case NALU_TYPE_SLICE:
      case NALU_TYPE_IDR:
        img->idr_flag = (nalu->nal_unit_type == NALU_TYPE_IDR);
        img->nal_reference_idc = nalu->nal_reference_idc;
        img->disposable_flag = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);
        currSlice->dp_mode = PAR_DP_1;
        currSlice->max_part_nr = 1;
        currSlice->ei_flag = 0;
        currStream = currSlice->partArr[0].bitstream;
        currStream->ei_flag = 0;
        currStream->frame_bitoffset = currStream->read_len = 0;
        memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
        currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);

        // Some syntax of the Slice Header depends on the parameter set, which depends on
        // the parameter set ID of the SLice header.  Hence, read the pic_parameter_set_id
        // of the slice header first, then setup the active parameter sets, and then read
        // the rest of the slice header
        BitsUsedByHeader = FirstPartOfSliceHeader();
        UseParameterSet (currSlice->pic_parameter_set_id);
        BitsUsedByHeader+= RestOfSliceHeader ();

        FmoInit (active_pps, active_sps);

        if(is_new_picture())
        {
          init_picture(img, input);
          
          current_header = SOP;
          //check zero_byte if it is also the first NAL unit in the access unit
          CheckZeroByteVCL(nalu, &ret);
        }
        else
          current_header = SOS;
  
        init_lists(img->type, img->currentSlice->structure);
        reorder_lists (img->type, img->currentSlice);

        if (img->structure==FRAME)
        {
          init_mbaff_lists();
        }

/*        if (img->frame_num==1) // write a reference list
        {
          count ++;
          if (count==1)
            for (i=0; i<listXsize[0]; i++)
              write_picture(listX[0][i], p_out2);
        }
*/

        // From here on, active_sps, active_pps and the slice header are valid
        if (img->MbaffFrameFlag)
          img->current_mb_nr = currSlice->start_mb_nr << 1;
        else
          img->current_mb_nr = currSlice->start_mb_nr;

        if (active_pps->entropy_coding_mode_flag)
        {
          int ByteStartPosition = currStream->frame_bitoffset/8;
          if (currStream->frame_bitoffset%8 != 0) 
          {
            ByteStartPosition++;
          }
          arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type);
        }
// printf ("read_new_slice: returning %s\n", current_header == SOP?"SOP":"SOS");
        FreeNALU(nalu);
        return current_header;
        break;
      case NALU_TYPE_DPA:
        //! The state machine here should follow the same ideas as the old readSliceRTP()
        //! basically:
        //! work on DPA (as above)
        //! read and process all following SEI/SPS/PPS/PD/Filler NALUs
        //! if next video NALU is dpB, 
        //!   then read and check whether it belongs to DPA, if yes, use it
        //! else
        //!   ;   // nothing
        //! read and process all following SEI/SPS/PPS/PD/Filler NALUs
        //! if next video NALU is dpC
        //!   then read and check whether it belongs to DPA (and DPB, if present), if yes, use it, done
        //! else
        //!   use the DPA (and the DPB if present)

        /* 
            LC: inserting the code related to DP processing, mainly copying some of the parts
            related to NALU_TYPE_SLICE, NALU_TYPE_IDR.
        */

        if(expected_slice_type != NALU_TYPE_DPA)
        {
          /* oops... we found the next slice, go back! */
          fseek(bits, ftell_position, SEEK_SET);
          FreeNALU(nalu);
          return current_header;
        }

        img->idr_flag          = (nalu->nal_unit_type == NALU_TYPE_IDR);
        img->nal_reference_idc = nalu->nal_reference_idc;
        img->disposable_flag   = (nalu->nal_reference_idc == NALU_PRIORITY_DISPOSABLE);
        currSlice->dp_mode     = PAR_DP_3;
        currSlice->max_part_nr = 3;
        currSlice->ei_flag     = 0;
        currStream             = currSlice->partArr[0].bitstream;
        currStream->ei_flag    = 0;
        currStream->frame_bitoffset = currStream->read_len = 0;
        memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
        currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);
        
        BitsUsedByHeader     = FirstPartOfSliceHeader();
        UseParameterSet (currSlice->pic_parameter_set_id);
        BitsUsedByHeader    += RestOfSliceHeader ();
        
        FmoInit (active_pps, active_sps);

        if(is_new_picture())
        {
          init_picture(img, input);
          current_header = SOP;
          CheckZeroByteVCL(nalu, &ret);
        }
        else
          current_header = SOS;

        
        init_lists(img->type, img->currentSlice->structure);
        reorder_lists (img->type, img->currentSlice);
        
        if (img->structure==FRAME)
        {
          init_mbaff_lists();
        }

        // From here on, active_sps, active_pps and the slice header are valid
        if (img->MbaffFrameFlag)
          img->current_mb_nr = currSlice->start_mb_nr << 1;
        else
          img->current_mb_nr = currSlice->start_mb_nr;


        /* 
           LC:
              Now I need to read the slice ID, which depends on the value of 
              redundant_pic_cnt_present_flag (pag.49). 
        */

        slice_id_a  = ue_v("NALU:SLICE_A slice_idr", currStream);
        if (active_pps->entropy_coding_mode_flag)
        {
          int ByteStartPosition = currStream->frame_bitoffset/8;
          if (currStream->frame_bitoffset%8 != 0) 
          {
            ByteStartPosition++;
          }
          arideco_start_decoding (&currSlice->partArr[0].de_cabac, currStream->streamBuffer, ByteStartPosition, &currStream->read_len, img->type);
        }
// printf ("read_new_slice: returning %s\n", current_header == SOP?"SOP":"SOS");
        break;
      case NALU_TYPE_DPB:
        /* LC: inserting the code related to DP processing */

        currStream             = currSlice->partArr[1].bitstream;
        currStream->ei_flag    = 0;
        currStream->frame_bitoffset = currStream->read_len = 0;
        memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
        currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);

        slice_id_b  = ue_v("NALU:SLICE_B slice_idr", currStream);
        if (active_pps->redundant_pic_cnt_present_flag)
          redundant_pic_cnt_b = ue_v("NALU:SLICE_B redudand_pic_cnt", currStream);
        else
          redundant_pic_cnt_b = 0;
        
        /*  LC: Initializing CABAC for the current data stream. */

        if (active_pps->entropy_coding_mode_flag)
        {
          int ByteStartPosition = currStream->frame_bitoffset/8;
          if (currStream->frame_bitoffset % 8 != 0) 
            ByteStartPosition++;
          
          arideco_start_decoding (&currSlice->partArr[1].de_cabac, currStream->streamBuffer, 
            ByteStartPosition, &currStream->read_len, img->type);
          
        }

        /* LC: resilience code to be inserted */
        /*         FreeNALU(nalu); */
        /*         return current_header; */

        break;
      case NALU_TYPE_DPC:
        /* LC: inserting the code related to DP processing */
        currStream             = currSlice->partArr[2].bitstream;
        currStream->ei_flag    = 0;
        currStream->frame_bitoffset = currStream->read_len = 0;
        memcpy (currStream->streamBuffer, &nalu->buf[1], nalu->len-1);
        currStream->code_len = currStream->bitstream_length = RBSPtoSODB(currStream->streamBuffer, nalu->len-1);
        
        slice_id_c  = ue_v("NALU:SLICE_C slice_idr", currStream);
        if (active_pps->redundant_pic_cnt_present_flag)
          redundant_pic_cnt_c = ue_v("NALU:SLICE_C redudand_pic_cnt", currStream);
        else
          redundant_pic_cnt_c = 0;
        
        /* LC: Initializing CABAC for the current data stream. */

        if (active_pps->entropy_coding_mode_flag)
        {
          int ByteStartPosition = currStream->frame_bitoffset/8;
          if (currStream->frame_bitoffset % 8 != 0) 
            ByteStartPosition++;
          
          arideco_start_decoding (&currSlice->partArr[2].de_cabac, currStream->streamBuffer, 
            ByteStartPosition, &currStream->read_len, img->type);
        }

        /* LC: resilience code to be inserted */