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/* getpic.c, picture decoding                                               */

/* Copyright (C) 1996, MPEG Software Simulation Group. All Rights Reserved. */

/*

 * Disclaimer of Warranty

 *

 * These software programs are available to the user without any license fee or

 * royalty on an "as is" basis.  The MPEG Software Simulation Group disclaims

 * any and all warranties, whether express, implied, or statuary, including any

 * implied warranties or merchantability or of fitness for a particular

 * purpose.  In no event shall the copyright-holder be liable for any

 * incidental, punitive, or consequential damages of any kind whatsoever

 * arising from the use of these programs.

 *

 * This disclaimer of warranty extends to the user of these programs and user's

 * customers, employees, agents, transferees, successors, and assigns.

 *

 * The MPEG Software Simulation Group does not represent or warrant that the

 * programs furnished hereunder are free of infringement of any third-party

 * patents.

 *

 * Commercial implementations of MPEG-1 and MPEG-2 video, including shareware,

 * are subject to royalty fees to patent holders.  Many of these patents are

 * general enough such that they are unavoidable regardless of implementation

 * design.

 *

 */

#include <stdio.h>

#include "config.h"

#include "global.h"

/* private prototypes*/

static void picture_data _ANSI_ARGS_((int framenum));

static void macroblock_modes _ANSI_ARGS_((int *pmacroblock_type, int *pstwtype,

  int *pstwclass, int *pmotion_type, int *pmotion_vector_count, int *pmv_format, int *pdmv,

  int *pmvscale, int *pdct_type));

static void Clear_Block _ANSI_ARGS_((int comp));

static void Sum_Block _ANSI_ARGS_((int comp));

static void Saturate _ANSI_ARGS_((short *bp));

static void Add_Block _ANSI_ARGS_((int comp, int bx, int by,

  int dct_type, int addflag));

static void Update_Picture_Buffers _ANSI_ARGS_((void));

static void frame_reorder _ANSI_ARGS_((int bitstream_framenum,

  int sequence_framenum));

static void Decode_SNR_Macroblock _ANSI_ARGS_((int *SNRMBA, int *SNRMBAinc,

  int MBA, int MBAmax, int *dct_type));

static void motion_compensation _ANSI_ARGS_((int MBA, int macroblock_type,

 int motion_type, int PMV[2][2][2], int motion_vertical_field_select[2][2],

 int dmvector[2], int stwtype, int dct_type));

static void skipped_macroblock _ANSI_ARGS_((int dc_dct_pred[3],

  int PMV[2][2][2], int *motion_type, int motion_vertical_field_select[2][2],

  int *stwtype, int *macroblock_type));

static int slice _ANSI_ARGS_((int framenum, int MBAmax));

static int start_of_slice _ANSI_ARGS_ ((int MBAmax, int *MBA,

  int *MBAinc, int dc_dct_pred[3], int PMV[2][2][2]));

static int decode_macroblock _ANSI_ARGS_((int *macroblock_type,

  int *stwtype, int *stwclass, int *motion_type, int *dct_type,

  int PMV[2][2][2], int dc_dct_pred[3],

  int motion_vertical_field_select[2][2], int dmvector[2]));

/* decode one frame or field picture */

void Decode_Picture(bitstream_framenum, sequence_framenum)

int bitstream_framenum, sequence_framenum;

{

  if (picture_structure==FRAME_PICTURE && Second_Field)

  {

    /* recover from illegal number of field pictures */

    printf("odd number of field pictures\n");

    Second_Field = 0;

  }

  /* IMPLEMENTATION: update picture buffer pointers */

  Update_Picture_Buffers();

#ifdef VERIFY 

  Check_Headers(bitstream_framenum, sequence_framenum);

#endif /* VERIFY */

  /* ISO/IEC 13818-4 section 2.4.5.4 "frame buffer intercept method" */

  /* (section number based on November 1995 (Dallas) draft of the

      conformance document) */

  if(Ersatz_Flag)

    Substitute_Frame_Buffer(bitstream_framenum, sequence_framenum);

  /* form spatial scalable picture */

  /* form spatial scalable picture */

  /* ISO/IEC 13818-2 section 7.7: Spatial scalability */

  if (base.pict_scal && !Second_Field)

  {

    Spatial_Prediction();

  }

  /* decode picture data ISO/IEC 13818-2 section 6.2.3.7 */

  picture_data(bitstream_framenum);

  /* write or display current or previously decoded reference frame */

  /* ISO/IEC 13818-2 section 6.1.1.11: Frame reordering */

  frame_reorder(bitstream_framenum, sequence_framenum);

  if (picture_structure!=FRAME_PICTURE)

    Second_Field = !Second_Field;

}

/* decode all macroblocks of the current picture */

/* stages described in ISO/IEC 13818-2 section 7 */

static void picture_data(framenum)

int framenum;

{

  int MBAmax;

  int ret;

  /* number of macroblocks per picture */

  MBAmax = mb_width*mb_height;

  if (picture_structure!=FRAME_PICTURE)

    MBAmax>>=1; /* field picture has half as mnay macroblocks as frame */

  for(;;)

  {

    if((ret=slice(framenum, MBAmax))<0)

      return;

  }

}

/* decode all macroblocks of the current picture */

/* ISO/IEC 13818-2 section 6.3.16 */

static int slice(framenum, MBAmax)

int framenum, MBAmax;

{

  int MBA;

  int MBAinc, macroblock_type, motion_type, dct_type;

  int dc_dct_pred[3];

  int PMV[2][2][2], motion_vertical_field_select[2][2];

  int dmvector[2];

  int stwtype, stwclass;

  int SNRMBA, SNRMBAinc;

  int ret;

  MBA = 0; /* macroblock address */

  MBAinc = 0;

  if((ret=start_of_slice(MBAmax, &MBA, &MBAinc, dc_dct_pred, PMV))!=1)

    return(ret);

  if (Two_Streams && enhan.scalable_mode==SC_SNR)

  {

    SNRMBA=0;

    SNRMBAinc=0;

  }

  Fault_Flag=0;

  for (;;)

  {

    /* this is how we properly exit out of picture */

    if (MBA>=MBAmax)

      return(-1); /* all macroblocks decoded */

#ifdef TRACE

    if (Trace_Flag)

      printf("frame %d, MB %d\n",framenum,MBA);

#endif /* TRACE */

#ifdef DISPLAY

    if (!progressive_frame && picture_structure==FRAME_PICTURE

      && MBA==(MBAmax>>1) && framenum!=0 && Output_Type==T_X11

       && !Display_Progressive_Flag)

    {

      Display_Second_Field();

    }

#endif

    ld = &base;

    if (MBAinc==0)

    {

      if (base.scalable_mode==SC_DP && base.priority_breakpoint==1)

          ld = &enhan;

      if (!Show_Bits(23) || Fault_Flag) /* next_start_code or fault */

      {

resync: /* if Fault_Flag: resynchronize to next next_start_code */

        Fault_Flag = 0;

        return(0);     /* trigger: go to next slice */

      }

      else /* neither next_start_code nor Fault_Flag */

      {

        if (base.scalable_mode==SC_DP && base.priority_breakpoint==1)

          ld = &enhan;

        /* decode macroblock address increment */

        MBAinc = Get_macroblock_address_increment();

        if (Fault_Flag) goto resync;

      }

    }

    if (MBA>=MBAmax)

    {

      /* MBAinc points beyond picture dimensions */

      if (!Quiet_Flag)

        printf("Too many macroblocks in picture\n");

      return(-1);

    }

    if (MBAinc==1) /* not skipped */

    {

      ret = decode_macroblock(&macroblock_type, &stwtype, &stwclass,

              &motion_type, &dct_type, PMV, dc_dct_pred,

              motion_vertical_field_select, dmvector);

      if(ret==-1)

        return(-1);

      if(ret==0)

        goto resync;

    }

    else /* MBAinc!=1: skipped macroblock */

    {      

      /* ISO/IEC 13818-2 section 7.6.6 */

      skipped_macroblock(dc_dct_pred, PMV, &motion_type,

        motion_vertical_field_select, &stwtype, &macroblock_type);

    }

    /* SCALABILITY: SNR */

    /* ISO/IEC 13818-2 section 7.8 */

    /* NOTE: we currently ignore faults encountered in this routine */

    if (Two_Streams && enhan.scalable_mode==SC_SNR)

      Decode_SNR_Macroblock(&SNRMBA, &SNRMBAinc, MBA, MBAmax, &dct_type);

    /* ISO/IEC 13818-2 section 7.6 */

    motion_compensation(MBA, macroblock_type, motion_type, PMV,

      motion_vertical_field_select, dmvector, stwtype, dct_type);

    /* advance to next macroblock */

    MBA++;

    MBAinc--;

    /* SCALABILITY: SNR */

    if (Two_Streams && enhan.scalable_mode==SC_SNR)

    {

      SNRMBA++;

      SNRMBAinc--;

    }

    if (MBA>=MBAmax)

      return(-1); /* all macroblocks decoded */

  }

}

/* ISO/IEC 13818-2 section 6.3.17.1: Macroblock modes */

static void macroblock_modes(pmacroblock_type,pstwtype,pstwclass,

  pmotion_type,pmotion_vector_count,pmv_format,pdmv,pmvscale,pdct_type)

  int *pmacroblock_type, *pstwtype, *pstwclass;

  int *pmotion_type, *pmotion_vector_count, *pmv_format, *pdmv, *pmvscale;

  int *pdct_type;

{

  int macroblock_type;

  int stwtype, stwcode, stwclass;

  int motion_type = 0;

  int motion_vector_count, mv_format, dmv, mvscale;

  int dct_type;

  static unsigned char stwc_table[3][4]

    = { {6,3,7,4}, {2,1,5,4}, {2,5,7,4} };

  static unsigned char stwclass_table[9]

    = {0, 1, 2, 1, 1, 2, 3, 3, 4};

  /* get macroblock_type */

  macroblock_type = Get_macroblock_type();

  if (Fault_Flag) return;

  /* get spatial_temporal_weight_code */

  if (macroblock_type & MB_WEIGHT)

  {

    if (spatial_temporal_weight_code_table_index==0)

      stwtype = 4;

    else

    {

      stwcode = Get_Bits(2);

#ifdef TRACE

      if (Trace_Flag)

      {

        printf("spatial_temporal_weight_code (");

        Print_Bits(stwcode,2,2);

        printf("): %d\n",stwcode);

      }

#endif /* TRACE */

      stwtype = stwc_table[spatial_temporal_weight_code_table_index-1][stwcode];

    }

  }

  else

    stwtype = (macroblock_type & MB_CLASS4) ? 8 : 0;

  /* SCALABILITY: derive spatial_temporal_weight_class (Table 7-18) */

  stwclass = stwclass_table[stwtype];

  /* get frame/field motion type */

  if (macroblock_type & (MACROBLOCK_MOTION_FORWARD|MACROBLOCK_MOTION_BACKWARD))

  {

    if (picture_structure==FRAME_PICTURE) /* frame_motion_type */

    {

      motion_type = frame_pred_frame_dct ? MC_FRAME : Get_Bits(2);

#ifdef TRACE

      if (!frame_pred_frame_dct && Trace_Flag)

      {

        printf("frame_motion_type (");

        Print_Bits(motion_type,2,2);

        printf("): %s\n",motion_type==MC_FIELD?"Field":

                         motion_type==MC_FRAME?"Frame":

                         motion_type==MC_DMV?"Dual_Prime":"Invalid");

      }

#endif /* TRACE */

    }

    else /* field_motion_type */

    {

      motion_type = Get_Bits(2);

#ifdef TRACE

      if (Trace_Flag)

      {

        printf("field_motion_type (");

        Print_Bits(motion_type,2,2);

        printf("): %s\n",motion_type==MC_FIELD?"Field":

                         motion_type==MC_16X8?"16x8 MC":

                         motion_type==MC_DMV?"Dual_Prime":"Invalid");

      }

#endif /* TRACE */

    }

  }

  else if ((macroblock_type & MACROBLOCK_INTRA) && concealment_motion_vectors)

  {

    /* concealment motion vectors */

    motion_type = (picture_structure==FRAME_PICTURE) ? MC_FRAME : MC_FIELD;

  }

#if 0

  else

  {

    printf("maroblock_modes(): unknown macroblock type\n");

    motion_type = -1;

  }

#endif

  /* derive motion_vector_count, mv_format and dmv, (table 6-17, 6-18) */

  if (picture_structure==FRAME_PICTURE)

  {

    motion_vector_count = (motion_type==MC_FIELD && stwclass<2) ? 2 : 1;

    mv_format = (motion_type==MC_FRAME) ? MV_FRAME : MV_FIELD;

  }

  else

  {

    motion_vector_count = (motion_type==MC_16X8) ? 2 : 1;

    mv_format = MV_FIELD;

  }

  dmv = (motion_type==MC_DMV); /* dual prime */

  /* field mv predictions in frame pictures have to be scaled

   * ISO/IEC 13818-2 section 7.6.3.1 Decoding the motion vectors

   * IMPLEMENTATION: mvscale is derived for later use in motion_vectors()

   * it displaces the stage:

   *

   *    if((mv_format=="field")&&(t==1)&&(picture_structure=="Frame picture"))

   *      prediction = PMV[r][s][t] DIV 2;

   */

  mvscale = ((mv_format==MV_FIELD) && (picture_structure==FRAME_PICTURE));

  /* get dct_type (frame DCT / field DCT) */

  dct_type = (picture_structure==FRAME_PICTURE)

             && (!frame_pred_frame_dct)

             && (macroblock_type & (MACROBLOCK_PATTERN|MACROBLOCK_INTRA))

             ? Get_Bits(1)

             : 0;

#ifdef TRACE

  if (Trace_Flag  && (picture_structure==FRAME_PICTURE)

             && (!frame_pred_frame_dct)

             && (macroblock_type & (MACROBLOCK_PATTERN|MACROBLOCK_INTRA)))

    printf("dct_type (%d): %s\n",dct_type,dct_type?"Field":"Frame");

#endif /* TRACE */

  /* return values */

  *pmacroblock_type = macroblock_type;

  *pstwtype = stwtype;

  *pstwclass = stwclass;

  *pmotion_type = motion_type;

  *pmotion_vector_count = motion_vector_count;

  *pmv_format = mv_format;

  *pdmv = dmv;

  *pmvscale = mvscale;

  *pdct_type = dct_type;

}

/* move/add 8x8-Block from block[comp] to backward_reference_frame */

/* copy reconstructed 8x8 block from block[comp] to current_frame[]

 * ISO/IEC 13818-2 section 7.6.8: Adding prediction and coefficient data

 * This stage also embodies some of the operations implied by:

 *   - ISO/IEC 13818-2 section 7.6.7: Combining predictions

 *   - ISO/IEC 13818-2 section 6.1.3: Macroblock

*/

static void Add_Block(comp,bx,by,dct_type,addflag)

int comp,bx,by,dct_type,addflag;

{

  int cc,i, j, iincr;

  unsigned char *rfp;

  short *bp;

  /* derive color component index */

  /* equivalent to ISO/IEC 13818-2 Table 7-1 */

  cc = (comp<4) ? 0 : (comp&1)+1; /* color component index */

  if (cc==0)

  {

    /* luminance */

    if (picture_structure==FRAME_PICTURE)

      if (dct_type)

      {

        /* field DCT coding */

        rfp = current_frame[0]

              + Coded_Picture_Width*(by+((comp&2)>>1)) + bx + ((comp&1)<<3);

        iincr = (Coded_Picture_Width<<1) - 8;

      }

      else

      {

        /* frame DCT coding */

        rfp = current_frame[0]

              + Coded_Picture_Width*(by+((comp&2)<<2)) + bx + ((comp&1)<<3);

        iincr = Coded_Picture_Width - 8;

      }

    else

    {

      /* field picture */

      rfp = current_frame[0]

            + (Coded_Picture_Width<<1)*(by+((comp&2)<<2)) + bx + ((comp&1)<<3);

      iincr = (Coded_Picture_Width<<1) - 8;

    }

  }

  else

  {

    /* chrominance */

    /* scale coordinates */

    if (chroma_format!=CHROMA444)

      bx >>= 1;

    if (chroma_format==CHROMA420)

      by >>= 1;

    if (picture_structure==FRAME_PICTURE)

    {

      if (dct_type && (chroma_format!=CHROMA420))

      {

        /* field DCT coding */

        rfp = current_frame[cc]

              + Chroma_Width*(by+((comp&2)>>1)) + bx + (comp&8);

        iincr = (Chroma_Width<<1) - 8;

      }

      else

      {

        /* frame DCT coding */

        rfp = current_frame[cc]

              + Chroma_Width*(by+((comp&2)<<2)) + bx + (comp&8);

        iincr = Chroma_Width - 8;

      }

    }

    else

    {

      /* field picture */

      rfp = current_frame[cc]

            + (Chroma_Width<<1)*(by+((comp&2)<<2)) + bx + (comp&8);

      iincr = (Chroma_Width<<1) - 8;

    }

  }

  bp = ld->block[comp];

  if (addflag)

  {

    for (i=0; i<8; i++)

    {

      for (j=0; j<8; j++)

      {

        *rfp = Clip[*bp++ + *rfp];

        rfp++;

      }

      rfp+= iincr;

    }

  }

  else

  {

    for (i=0; i<8; i++)

    {

      for (j=0; j<8; j++)

        *rfp++ = Clip[*bp++ + 128];

      rfp+= iincr;

    }

  }

}

/* ISO/IEC 13818-2 section 7.8 */

static void Decode_SNR_Macroblock(SNRMBA, SNRMBAinc, MBA, MBAmax, dct_type)

  int *SNRMBA, *SNRMBAinc;

  int MBA, MBAmax;

  int *dct_type;

{

  int SNRmacroblock_type, SNRcoded_block_pattern, SNRdct_type, dummy;

  int slice_vert_pos_ext, quantizer_scale_code, comp, code;

  ld = &enhan;

  if (*SNRMBAinc==0)

  {

    if (!Show_Bits(23)) /* next_start_code */

    {

      next_start_code();

      code = Show_Bits(32);

      if (code<SLICE_START_CODE_MIN || code>SLICE_START_CODE_MAX)

      {

        /* only slice headers are allowed in picture_data */

        if (!Quiet_Flag)

          printf("SNR: Premature end of picture\n");

        return;

      }

      Flush_Buffer32();

      /* decode slice header (may change quantizer_scale) */

      slice_vert_pos_ext = slice_header();

      /* decode macroblock address increment */

      *SNRMBAinc = Get_macroblock_address_increment();

      /* set current location */

      *SNRMBA =

        ((slice_vert_pos_ext<<7) + (code&255) - 1)*mb_width + *SNRMBAinc - 1;

      *SNRMBAinc = 1; /* first macroblock in slice: not skipped */

    }

    else /* not next_start_code */

    {

      if (*SNRMBA>=MBAmax)

      {

        if (!Quiet_Flag)

          printf("Too many macroblocks in picture\n");

        return;

      }

      /* decode macroblock address increment */

      *SNRMBAinc = Get_macroblock_address_increment();

    }

  }

  if (*SNRMBA!=MBA)

  {

    /* streams out of sync */

    if (!Quiet_Flag)

      printf("Cant't synchronize streams\n");

    return;

  }

  if (*SNRMBAinc==1) /* not skipped */

  {

    macroblock_modes(&SNRmacroblock_type, &dummy, &dummy,

      &dummy, &dummy, &dummy, &dummy, &dummy,

      &SNRdct_type);

    if (SNRmacroblock_type & MACROBLOCK_PATTERN)

      *dct_type = SNRdct_type;

    if (SNRmacroblock_type & MACROBLOCK_QUANT)

    {

      quantizer_scale_code = Get_Bits(5);

      ld->quantizer_scale =

        ld->q_scale_type ? Non_Linear_quantizer_scale[quantizer_scale_code] : quantizer_scale_code<<1;

    }

    /* macroblock_pattern */

    if (SNRmacroblock_type & MACROBLOCK_PATTERN)

    {

      SNRcoded_block_pattern = Get_coded_block_pattern();

      if (chroma_format==CHROMA422)

        SNRcoded_block_pattern = (SNRcoded_block_pattern<<2) | Get_Bits(2); /* coded_block_pattern_1 */

      else if (chroma_format==CHROMA444)

        SNRcoded_block_pattern = (SNRcoded_block_pattern<<6) | Get_Bits(6); /* coded_block_pattern_2 */

    }

    else

      SNRcoded_block_pattern = 0;

    /* decode blocks */

    for (comp=0; comp<block_count; comp++)

    {

      Clear_Block(comp);

      if (SNRcoded_block_pattern & (1<<(block_count-1-comp)))

        Decode_MPEG2_Non_Intra_Block(comp);

    }

  }

  else /* SNRMBAinc!=1: skipped macroblock */

  {

    for (comp=0; comp<block_count; comp++)

      Clear_Block(comp);

  }

  ld = &base;

}

/* IMPLEMENTATION: set scratch pad macroblock to zero */

static void Clear_Block(comp)

int comp;

{

  short *Block_Ptr;

  int i;

  Block_Ptr = ld->block[comp];

  for (i=0; i<64; i++)

    *Block_Ptr++ = 0;

}

/* SCALABILITY: add SNR enhancement layer block data to base layer */

/* ISO/IEC 13818-2 section 7.8.3.4: Addition of coefficients from the two layes */

static void Sum_Block(comp)

int comp;

{

  short *Block_Ptr1, *Block_Ptr2;

  int i;

  Block_Ptr1 = base.block[comp];

  Block_Ptr2 = enhan.block[comp];

  for (i=0; i<64; i++)

    *Block_Ptr1++ += *Block_Ptr2++;

}

/* limit coefficients to -2048..2047 */

/* ISO/IEC 13818-2 section 7.4.3 and 7.4.4: Saturation and Mismatch control */

static void Saturate(Block_Ptr)

short *Block_Ptr;

{

  int i, sum, val;

  sum = 0;

  /* ISO/IEC 13818-2 section 7.4.3: Saturation */

  for (i=0; i<64; i++)

  {

    val = Block_Ptr[i];

    if (val>2047)

      val = 2047;

    else if (val<-2048)

      val = -2048;

    Block_Ptr[i] = val;

    sum+= val;

  }

  /* ISO/IEC 13818-2 section 7.4.4: Mismatch control */

  if ((sum&1)==0)

    Block_Ptr[63]^= 1;

}

/* reuse old picture buffers as soon as they are no longer needed

   based on life-time axioms of MPEG */

static void Update_Picture_Buffers()

{                          

  int cc;              /* color component index */

  unsigned char *tmp;  /* temporary swap pointer */

  for (cc=0; cc<3; cc++)

  {

    /* B pictures do not need to be save for future reference */

    if (picture_coding_type==B_TYPE)

    {

      current_frame[cc] = auxframe[cc];

    }

    else

    {

      /* only update at the beginning of the coded frame */

      if (!Second_Field)

      {

        tmp = forward_reference_frame[cc];

        /* the previously decoded reference frame is stored

           coincident with the location where the backward

           reference frame is stored (backwards prediction is not

           needed in P pictures) */

        forward_reference_frame[cc] = backward_reference_frame[cc];

        /* update pointer for potential future B pictures */

        backward_reference_frame[cc] = tmp;

      }

      /* can erase over old backward reference frame since it is not used

         in a P picture, and since any subsequent B pictures will use the

         previously decoded I or P frame as the backward_reference_frame */

      current_frame[cc] = backward_reference_frame[cc];

    }

    /* IMPLEMENTATION:

       one-time folding of a line offset into the pointer which stores the

       memory address of the current frame saves offsets and conditional

       branches throughout the remainder of the picture processing loop */

    if (picture_structure==BOTTOM_FIELD)

      current_frame[cc]+= (cc==0) ? Coded_Picture_Width : Chroma_Width;

  }

}

/* store last frame */

void Output_Last_Frame_of_Sequence(Framenum)

int Framenum;

{

  if (Second_Field)

    printf("last frame incomplete, not stored\n");

  else

    Write_Frame(backward_reference_frame,Framenum-1);

}

static void frame_reorder(Bitstream_Framenum, Sequence_Framenum)

int Bitstream_Framenum, Sequence_Framenum;

{

  /* tracking variables to insure proper output in spatial scalability */

  static int Oldref_progressive_frame, Newref_progressive_frame;

  if (Sequence_Framenum!=0)

  {

    if (picture_structure==FRAME_PICTURE || Second_Field)

    {

      if (picture_coding_type==B_TYPE)

        Write_Frame(auxframe,Bitstream_Framenum-1);

      else

      {

        Newref_progressive_frame = progressive_frame;

        progressive_frame = Oldref_progressive_frame;

        Write_Frame(forward_reference_frame,Bitstream_Framenum-1);

        Oldref_progressive_frame = progressive_frame = Newref_progressive_frame;

      }

    }

#ifdef DISPLAY

    else if (Output_Type==T_X11)

    {

      if(!Display_Progressive_Flag)

        Display_Second_Field();

    }

#endif

  }

  else

    Oldref_progressive_frame = progressive_frame;

}