/* transfrm.c,  前向/逆變換*/#include <stdio.h>#include <math.h>#include "config.h"#include "global.h"/* private prototypes*/static void add_pred _ANSI_ARGS_((unsigned char *pred, unsigned char *cur,  int lx, short *blk));static void sub_pred _ANSI_ARGS_((unsigned char *pred, unsigned char *cur,  int lx, short *blk));/* subtract prediction and transform prediction error */void transform(pred,cur,mbi,blocks)unsigned char *pred[], *cur[];struct mbinfo *mbi;short blocks[][64];{  int i, j, i1, j1, k, n, cc, offs, lx;  k = 0;  for (j=0; j<height2; j+=16)    for (i=0; i<width; i+=16)    {      for (n=0; n<block_count; n++)      {        cc = (n<4) ? 0 : (n&1)+1; /* color component index */        if (cc==0)        {          /* luminance */          if ((pict_struct==FRAME_PICTURE) && mbi[k].dct_type)          {            /* field DCT */            offs = i + ((n&1)<<3) + width*(j+((n&2)>>1));            lx = width<<1;          }          else          {            /* frame DCT */            offs = i + ((n&1)<<3) + width2*(j+((n&2)<<2));            lx = width2;          }          if (pict_struct==BOTTOM_FIELD)            offs += width;        }        else        {          /* chrominance */          /* scale coordinates */          i1 = (chroma_format==CHROMA444) ? i : i>>1;          j1 = (chroma_format!=CHROMA420) ? j : j>>1;          if ((pict_struct==FRAME_PICTURE) && mbi[k].dct_type              && (chroma_format!=CHROMA420))          {            /* field DCT */            offs = i1 + (n&8) + chrom_width*(j1+((n&2)>>1));            lx = chrom_width<<1;          }          else          {            /* frame DCT */            offs = i1 + (n&8) + chrom_width2*(j1+((n&2)<<2));            lx = chrom_width2;          }          if (pict_struct==BOTTOM_FIELD)            offs += chrom_width;        }        sub_pred(pred[cc]+offs,cur[cc]+offs,lx,blocks[k*block_count+n]);        fdct(blocks[k*block_count+n]);      }      k++;    }}/* inverse transform prediction error and add prediction */void itransform(pred,cur,mbi,blocks)unsigned char *pred[],*cur[];struct mbinfo *mbi;short blocks[][64];{  int i, j, i1, j1, k, n, cc, offs, lx;  k = 0;  for (j=0; j<height2; j+=16)    for (i=0; i<width; i+=16)    {      for (n=0; n<block_count; n++)      {        cc = (n<4) ? 0 : (n&1)+1; /* color component index */        if (cc==0)        {          /* luminance */          if ((pict_struct==FRAME_PICTURE) && mbi[k].dct_type)          {            /* field DCT */            offs = i + ((n&1)<<3) + width*(j+((n&2)>>1));            lx = width<<1;          }          else          {            /* frame DCT */            offs = i + ((n&1)<<3) + width2*(j+((n&2)<<2));            lx = width2;          }          if (pict_struct==BOTTOM_FIELD)            offs += width;        }        else        {          /* chrominance */          /* scale coordinates */          i1 = (chroma_format==CHROMA444) ? i : i>>1;          j1 = (chroma_format!=CHROMA420) ? j : j>>1;          if ((pict_struct==FRAME_PICTURE) && mbi[k].dct_type              && (chroma_format!=CHROMA420))          {            /* field DCT */            offs = i1 + (n&8) + chrom_width*(j1+((n&2)>>1));            lx = chrom_width<<1;          }          else          {            /* frame DCT */            offs = i1 + (n&8) + chrom_width2*(j1+((n&2)<<2));            lx = chrom_width2;          }          if (pict_struct==BOTTOM_FIELD)            offs += chrom_width;        }        idct(blocks[k*block_count+n]);        add_pred(pred[cc]+offs,cur[cc]+offs,lx,blocks[k*block_count+n]);      }      k++;    }}/* add prediction and prediction error, saturate to 0...255 */static void add_pred(pred,cur,lx,blk)unsigned char *pred, *cur;int lx;short *blk;{  int i, j;  for (j=0; j<8; j++)  {    for (i=0; i<8; i++)      cur[i] = clp[blk[i] + pred[i]];    blk+= 8;    cur+= lx;    pred+= lx;  }}/* subtract prediction from block data */static void sub_pred(pred,cur,lx,blk)unsigned char *pred, *cur;int lx;short *blk;{  int i, j;  for (j=0; j<8; j++)  {    for (i=0; i<8; i++)      blk[i] = cur[i] - pred[i];    blk+= 8;    cur+= lx;    pred+= lx;  }}/* * select between frame and field DCT * * preliminary version: based on inter-field correlation */void dct_type_estimation(pred,cur,mbi)unsigned char *pred,*cur;struct mbinfo *mbi;{  short blk0[128], blk1[128];  int i, j, i0, j0, k, offs, s0, s1, sq0, sq1, s01;  double d, r;  k = 0;  for (j0=0; j0<height2; j0+=16)    for (i0=0; i0<width; i0+=16)    {      if (frame_pred_dct || pict_struct!=FRAME_PICTURE)        mbi[k].dct_type = 0;      else      {        /* interlaced frame picture */        /*         * calculate prediction error (cur-pred) for top (blk0)         * and bottom field (blk1)         */        for (j=0; j<8; j++)        {          offs = width*((j<<1)+j0) + i0;          for (i=0; i<16; i++)          {            blk0[16*j+i] = cur[offs] - pred[offs];            blk1[16*j+i] = cur[offs+width] - pred[offs+width];            offs++;          }        }        /* correlate fields */        s0=s1=sq0=sq1=s01=0;        for (i=0; i<128; i++)        {          s0+= blk0[i];          sq0+= blk0[i]*blk0[i];          s1+= blk1[i];          sq1+= blk1[i]*blk1[i];          s01+= blk0[i]*blk1[i];        }        d = (sq0-(s0*s0)/128.0)*(sq1-(s1*s1)/128.0);        if (d>0.0)        {          r = (s01-(s0*s1)/128.0)/sqrt(d);          if (r>0.5)            mbi[k].dct_type = 0; /* frame DCT */          else            mbi[k].dct_type = 1; /* field DCT */        }        else          mbi[k].dct_type = 1; /* field DCT */      }      k++;    }}