mpeg2enc.c

MPEG2视频编解码算法方面的源代码(包括编码和解码)

  prog_frame = !!prog_frame;

  /* make sure MPEG specific parameters are valid */
  range_checks();

  frame_rate = ratetab[frame_rate_code-1];

  /* timecode -> frame number */
  tc0 = h;
  tc0 = 60*tc0 + m;
  tc0 = 60*tc0 + s;
  tc0 = (int)(frame_rate+0.5)*tc0 + f;

  if (!mpeg1)
  {
    profile_and_level_checks();
  }
  else
  {
    /* MPEG-1 */
    if (constrparms)
    {
      if (horizontal_size>768
          || vertical_size>576
          || ((horizontal_size+15)/16)*((vertical_size+15)/16)>396
          || ((horizontal_size+15)/16)*((vertical_size+15)/16)*frame_rate>396*25.0
          || frame_rate>30.0)
      {
        if (!quiet)
          fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
        constrparms = 0;
      }
    }

    if (constrparms)
    {
      for (i=0; i<M; i++)
      {
        if (motion_data[i].forw_hor_f_code>4)
        {
          if (!quiet)
            fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
          constrparms = 0;
          break;
        }

        if (motion_data[i].forw_vert_f_code>4)
        {
          if (!quiet)
            fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
          constrparms = 0;
          break;
        }

        if (i!=0)
        {
          if (motion_data[i].back_hor_f_code>4)
          {
            if (!quiet)
              fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
            constrparms = 0;
            break;
          }

          if (motion_data[i].back_vert_f_code>4)
          {
            if (!quiet)
              fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
            constrparms = 0;
            break;
          }
        }
      }
    }
  }

  /* relational checks */

  if (mpeg1)
  {
    if (!prog_seq)
    {
      if (!quiet)
        fprintf(stderr,"Warning: setting progressive_sequence = 1\n");
      prog_seq = 1;
    }

    if (chroma_format!=CHROMA420)
    {
      if (!quiet)
        fprintf(stderr,"Warning: setting chroma_format = 1 (4:2:0)\n");
      chroma_format = CHROMA420;
    }

    if (dc_prec!=0)
    {
      if (!quiet)
        fprintf(stderr,"Warning: setting intra_dc_precision = 0\n");
      dc_prec = 0;
    }

    for (i=0; i<3; i++)
      if (qscale_tab[i])
      {
        if (!quiet)
          fprintf(stderr,"Warning: setting qscale_tab[%d] = 0\n",i);
        qscale_tab[i] = 0;
      }

    for (i=0; i<3; i++)
      if (intravlc_tab[i])
      {
        if (!quiet)
          fprintf(stderr,"Warning: setting intravlc_tab[%d] = 0\n",i);
        intravlc_tab[i] = 0;
      }

    for (i=0; i<3; i++)
      if (altscan_tab[i])
      {
        if (!quiet)
          fprintf(stderr,"Warning: setting altscan_tab[%d] = 0\n",i);
        altscan_tab[i] = 0;
      }
  }

  if (!mpeg1 && constrparms)
  {
    if (!quiet)
      fprintf(stderr,"Warning: setting constrained_parameters_flag = 0\n");
    constrparms = 0;
  }

  if (prog_seq && !prog_frame)
  {
    if (!quiet)
      fprintf(stderr,"Warning: setting progressive_frame = 1\n");
    prog_frame = 1;
  }

  if (prog_frame && fieldpic)
  {
    if (!quiet)
      fprintf(stderr,"Warning: setting field_pictures = 0\n");
    fieldpic = 0;
  }

  if (!prog_frame && repeatfirst)
  {
    if (!quiet)
      fprintf(stderr,"Warning: setting repeat_first_field = 0\n");
    repeatfirst = 0;
  }

  if (prog_frame)
  {
    for (i=0; i<3; i++)
      if (!frame_pred_dct_tab[i])
      {
        if (!quiet)
          fprintf(stderr,"Warning: setting frame_pred_frame_dct[%d] = 1\n",i);
        frame_pred_dct_tab[i] = 1;
      }
  }

  if (prog_seq && !repeatfirst && topfirst)
  {
    if (!quiet)
      fprintf(stderr,"Warning: setting top_field_first = 0\n");
    topfirst = 0;
  }

  /* search windows */
  for (i=0; i<M; i++)
  {
    if (motion_data[i].sxf > (4<<motion_data[i].forw_hor_f_code)-1)
    {
      if (!quiet)
        fprintf(stderr,
          "Warning: reducing forward horizontal search width to %d\n",
          (4<<motion_data[i].forw_hor_f_code)-1);
      motion_data[i].sxf = (4<<motion_data[i].forw_hor_f_code)-1;
    }

    if (motion_data[i].syf > (4<<motion_data[i].forw_vert_f_code)-1)
    {
      if (!quiet)
        fprintf(stderr,
          "Warning: reducing forward vertical search width to %d\n",
          (4<<motion_data[i].forw_vert_f_code)-1);
      motion_data[i].syf = (4<<motion_data[i].forw_vert_f_code)-1;
    }

    if (i!=0)
    {
      if (motion_data[i].sxb > (4<<motion_data[i].back_hor_f_code)-1)
      {
        if (!quiet)
          fprintf(stderr,
            "Warning: reducing backward horizontal search width to %d\n",
            (4<<motion_data[i].back_hor_f_code)-1);
        motion_data[i].sxb = (4<<motion_data[i].back_hor_f_code)-1;
      }

      if (motion_data[i].syb > (4<<motion_data[i].back_vert_f_code)-1)
      {
        if (!quiet)
          fprintf(stderr,
            "Warning: reducing backward vertical search width to %d\n",
            (4<<motion_data[i].back_vert_f_code)-1);
        motion_data[i].syb = (4<<motion_data[i].back_vert_f_code)-1;
      }
    }
  }

}

static void readquantmat()
{
  int i,v;
  FILE *fd;

  if (iqname[0]=='-')
  {
    /* use default intra matrix */
    load_iquant = 0;
    for (i=0; i<64; i++)
      intra_q[i] = default_intra_quantizer_matrix[i];
  }
  else
  {
    /* read customized intra matrix */
    load_iquant = 1;
    if (!(fd = fopen(iqname,"r")))
    {
      sprintf(errortext,"Couldn't open quant matrix file %s",iqname);
      error(errortext);
    }

    for (i=0; i<64; i++)
    {
      fscanf(fd,"%d",&v);
      if (v<1 || v>255)
        error("invalid value in quant matrix");
      intra_q[i] = v;
    }

    fclose(fd);
  }

  if (niqname[0]=='-')
  {
    /* use default non-intra matrix */
    load_niquant = 0;
    for (i=0; i<64; i++)
      inter_q[i] = 16;
  }
  else
  {
    /* read customized non-intra matrix */
    load_niquant = 1;
    if (!(fd = fopen(niqname,"r")))
    {
      sprintf(errortext,"Couldn't open quant matrix file %s",niqname);
      error(errortext);
    }

    for (i=0; i<64; i++)
    {
      fscanf(fd,"%d",&v);
      if (v<1 || v>255)
        error("invalid value in quant matrix");
      inter_q[i] = v;
    }

    fclose(fd);
  }
}