image.c

可以用H.264编码解码器源码(c语言)

  if (diff_u == 0)
      diff_u = 1;
  if (diff_v == 0)
      diff_v = 1; */

  // Collecting SNR statistics
  if (diff_y != 0)
    snr->snr_y=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)diff_y));        // luma snr for current frame
  else
    snr->snr_y=0;
  if (diff_u != 0)
    snr->snr_u=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)(4*diff_u)));    //  chroma snr for current frame
  else
    snr->snr_u=0;
  if (diff_v != 0)
    snr->snr_v=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)(4*diff_v)));    //  chroma snr for current frame
  else
    snr->snr_v=0;

  if (img->number == 0) // first
  {
    snr->snr_y1=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)diff_y));       // keep luma snr for first frame
    snr->snr_u1=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)(4*diff_u)));   // keep chroma snr for first frame
    snr->snr_v1=(float)(10*log10(65025*(float)(img->width)*(img->height)/(float)(4*diff_v)));   // keep chroma snr for first frame
    snr->snr_ya=snr->snr_y1;
    snr->snr_ua=snr->snr_u1;
    snr->snr_va=snr->snr_v1;
    
    if (diff_y == 0)   
      snr->snr_ya=50; // need to assign a reasonable large number so avg snr of entire sequece isn't infinite
    if (diff_u == 0)
      snr->snr_ua=50;
    if (diff_v == 0)
      snr->snr_va=50;

  }
/*  else
  {
    snr->snr_ya=(float)(snr->snr_ya*(img->number+Bframe_ctr)+snr->snr_y)/(img->number+Bframe_ctr+1); // average snr chroma for all frames
    snr->snr_ua=(float)(snr->snr_ua*(img->number+Bframe_ctr)+snr->snr_u)/(img->number+Bframe_ctr+1); // average snr luma for all frames
    snr->snr_va=(float)(snr->snr_va*(img->number+Bframe_ctr)+snr->snr_v)/(img->number+Bframe_ctr+1); // average snr luma for all frames
  } */
 else
  {
    snr->snr_ya=(float)(snr->snr_ya*(img->number - 1 + Bframe_ctr)+snr->snr_y)/(img->number+Bframe_ctr); // average snr luma for all frames
    snr->snr_ua=(float)(snr->snr_ua*(img->number - 1 + Bframe_ctr)+snr->snr_u)/(img->number+Bframe_ctr); // average snr chroma for all frames
    snr->snr_va=(float)(snr->snr_va*(img->number - 1 + Bframe_ctr)+snr->snr_v)/(img->number+Bframe_ctr); // average snr chromafor all frames
  }
}


/*!
 ************************************************************************
 * \brief
 *    Interpolation of 1/4 subpixel
 ************************************************************************
 */
void get_block(int ref_frame, StorablePicture **list, int x_pos, int y_pos, struct img_par *img, int block[BLOCK_SIZE][BLOCK_SIZE])
{

  int dx, dy;
  int x, y;
  int i, j;
  int maxold_x,maxold_y;
  int result;
  int pres_x;
  int pres_y; 
  int tmp_res[4][9];
  static const int COEF[6] = {
    1, -5, 20, 20, -5, 1
  };

  dx = x_pos&3;
  dy = y_pos&3;
  x_pos = (x_pos-dx)/4;
  y_pos = (y_pos-dy)/4;

  maxold_x = img->width-1;
  maxold_y = img->height-1;

  if (dec_picture->mb_field[img->current_mb_nr])
    maxold_y = img->height/2 - 1;

  if (dx == 0 && dy == 0) {  /* fullpel position */
    for (j = 0; j < BLOCK_SIZE; j++)
      for (i = 0; i < BLOCK_SIZE; i++)
        block[i][j] = list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j))][max(0,min(maxold_x,x_pos+i))];
  }
  else { /* other positions */

    if (dy == 0) { /* No vertical interpolation */

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

      if ((dx&1) == 1) {
        for (j = 0; j < BLOCK_SIZE; j++)
          for (i = 0; i < BLOCK_SIZE; i++)
            block[i][j] = (block[i][j] + list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j))][max(0,min(maxold_x,x_pos+i+dx/2))] +1 )/2;
      }
    }
    else if (dx == 0) {  /* No horizontal interpolation */

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

      if ((dy&1) == 1) {
        for (j = 0; j < BLOCK_SIZE; j++)
          for (i = 0; i < BLOCK_SIZE; i++)
           block[i][j] = (block[i][j] + list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j+dy/2))][max(0,min(maxold_x,x_pos+i))] +1 )/2;
      }
    }
    else if (dx == 2) {  /* Vertical & horizontal interpolation */

      for (j = -2; j < BLOCK_SIZE+3; j++) {
        for (i = 0; i < BLOCK_SIZE; i++)
          for (tmp_res[i][j+2] = 0, x = -2; x < 4; x++)
            tmp_res[i][j+2] += list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j))][max(0,min(maxold_x,x_pos+i+x))]*COEF[x+2];
      }

      for (j = 0; j < BLOCK_SIZE; j++) {
        for (i = 0; i < BLOCK_SIZE; i++) {
          for (result = 0, y = -2; y < 4; y++)
            result += tmp_res[i][j+y+2]*COEF[y+2];
          block[i][j] = max(0, min(255, (result+512)/1024));
        } 
      }

      if ((dy&1) == 1) {
        for (j = 0; j < BLOCK_SIZE; j++)
          for (i = 0; i < BLOCK_SIZE; i++)
            block[i][j] = (block[i][j] + max(0, min(255, (tmp_res[i][j+2+dy/2]+16)/32)) +1 )/2;
      }
    }
    else if (dy == 2) {  /* Horizontal & vertical interpolation */

      for (j = 0; j < BLOCK_SIZE; j++) {
        for (i = -2; i < BLOCK_SIZE+3; i++)
          for (tmp_res[j][i+2] = 0, y = -2; y < 4; y++)
            tmp_res[j][i+2] += list[ref_frame]->imgY[max(0,min(maxold_y,y_pos+j+y))][max(0,min(maxold_x,x_pos+i))]*COEF[y+2];
      }

      for (j = 0; j < BLOCK_SIZE; j++) {
        for (i = 0; i < BLOCK_SIZE; i++) {
          for (result = 0, x = -2; x < 4; x++)
            result += tmp_res[j][i+x+2]*COEF[x+2];
          block[i][j] = max(0, min(255, (result+512)/1024));
        }
      }

      if ((dx&1) == 1) {
        for (j = 0; j < BLOCK_SIZE; j++)
          for (i = 0; i < BLOCK_SIZE; i++)
            block[i][j] = (block[i][j] + max(0, min(255, (tmp_res[j][i+2+dx/2]+16)/32))+1)/2;
      }
    }
    else {  /* Diagonal interpolation */

      for (j = 0; j < BLOCK_SIZE; j++) {
        for (i = 0; i < BLOCK_SIZE; i++) {
          pres_y = dy == 1 ? y_pos+j : y_pos+j+1;
          pres_y = max(0,min(maxold_y,pres_y));
          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;
        }
      }

    }
  }

}


static 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 (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);
    }
  }

  free_ref_pic_list_reordering_buffer(currSlice);
}


/*!
 ************************************************************************
 * \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 newframe;

  int slice_id_a, slice_id_b, slice_id_c;
  int redundant_pic_cnt_a, 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);

    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);

        init_lists(img->type, img->currentSlice->structure);
        reorder_lists (img->type, img->currentSlice);

/*        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);
        }
*/
        if (img->MbaffFrameFlag)
        {
          init_mbaff_lists();
        }

        if (img->currentSlice->structure!=0)
        {
          img->height /=2 ;
          img->height_cr /=2;
        }

        // From here on, active_sps, active_pps and the slice header are valid
        img->current_mb_nr = currSlice->start_mb_nr;

        if (img->tr_old != img->ThisPOC)
        {
          newframe=1;
          img->tr_old = img->ThisPOC;
        }
        else
          newframe = 0;
        if (newframe)
          current_header = SOP;
        else
          current_header = SOS;

        if(img->structure != img->structure_old)        
          newframe |= 1;

        img->structure_old = img->structure; 
//! new stuff StW
        if(newframe || g_new_frame)
        {
          current_header = SOP;
          g_new_frame=0;
        }
        else
          current_header = SOS;

        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