/* predict.c, 運動補償預測*/#include <stdio.h>#include "config.h"#include "global.h"/* private prototypes */static void predict_mb _ANSI_ARGS_((  unsigned char *oldref[], unsigned char *newref[], unsigned char *cur[],  int lx, int bx, int by, int pict_type, int pict_struct, int mb_type,  int motion_type, int secondfield,  int PMV[2][2][2], int mv_field_sel[2][2], int dmvector[2]));static void pred _ANSI_ARGS_((unsigned char *src[], int sfield,  unsigned char *dst[], int dfield,  int lx, int w, int h, int x, int y, int dx, int dy, int addflag));static void pred_comp _ANSI_ARGS_((unsigned char *src, unsigned char *dst,  int lx, int w, int h, int x, int y, int dx, int dy, int addflag));static void calc_DMV _ANSI_ARGS_((int DMV[][2], int *dmvector, int mvx,  int mvy));static void clearblock _ANSI_ARGS_((unsigned char *cur[], int i0, int j0));/* 為完整的圖像形成預測 *    reff: 前向參考圖像幀
    refb: 后向參考圖像幀
	cur: 目標幀（即當前要預測的幀）
	secondfield: 預測幀的第二個場圖像
	mbi: 指向宏塊信息結構體的指針
 */void predict(reff,refb,cur,secondfield,mbi)unsigned char *reff[],*refb[],*cur[3];int secondfield;struct mbinfo *mbi;{  int i, j, k;  k = 0;  /* 對所有的宏塊進行循環 */
  for (j=0; j<height2; j+=16)    for (i=0; i<width; i+=16)    {      predict_mb(reff,refb,cur,width,i,j,pict_type,pict_struct,                 mbi[k].mb_type,mbi[k].motion_type,secondfield,                 mbi[k].MV,mbi[k].mv_field_sel,mbi[k].dmvector);      k++;    }}/* 為一個宏塊形成預測 * 	oldref: 用來進行前向預測的參考幀
	newref: 用來進行后向預測的參考幀
	cur: 目標幀（即當前要預測的幀）
	lx: 幀的寬度（與全局變量"width"一致）
	bx、by: 要被預測的宏塊的圖像坐標（可以是場，也可以是幀）
	pict_type: 圖像類型，就是I、P或B
	pict_struct: 圖像的結構，就是幀圖像（FRAME_PICTURE），上部分的場圖像
	（TOP_FIELD）和下部分的場圖像（BOTTOM_FIELD）
	
	mb_type: 宏塊類型，可以是前向（MB_FORWARD）,也可以是后向（MB_BACKWARD）
	或是幀內（MB_INTRA）宏塊
	
	  motion_type: 運動類型，主要用值MC_FRAME, MC_FIELD、MC_16X8、MC_DMV表示
	secondfield: 預測幀的第二個場圖像
	PMV[2][2][2]: 運動向量（以半像素圖像坐標為單位）
	mv_field_sel[2][2]: 垂直運動場選擇（針對場預測）
	dmvector: 差分運動向量
 */static void predict_mb(oldref,newref,cur,lx,bx,by,pict_type,pict_struct,  mb_type,motion_type,secondfield,PMV,mv_field_sel,dmvector)unsigned char *oldref[],*newref[],*cur[];int lx;int bx,by;int pict_type;int pict_struct;int mb_type;int motion_type;int secondfield;int PMV[2][2][2], mv_field_sel[2][2], dmvector[2];{  int addflag, currentfield;  unsigned char **predframe;  int DMV[2][2];  if (mb_type&MB_INTRA)  {    clearblock(cur,bx,by);    return;  }  addflag = 0;  /* 第一個預測值要存儲起來，然后加上第二個并取平均 */  if ((mb_type & MB_FORWARD) || (pict_type==P_TYPE))  {    /* 前向預測，包括P圖像里面的0運動向量 */    if (pict_struct==FRAME_PICTURE)    {      /* 幀圖像 */

      if ((motion_type==MC_FRAME) || !(mb_type & MB_FORWARD))      {  /* 幀圖像中，基于幀的預測 */
		  pred(oldref,0,cur,0,          lx,16,16,bx,by,PMV[0][0][0],PMV[0][0][1],0);      }      else if (motion_type==MC_FIELD)      {         /* 幀圖像中，基于場的預測-based prediction in frame picture
         *并非按照垂直坐標的比例
         */
        /* 上部分場圖像的預測 */
		  pred(oldref,mv_field_sel[0][0],cur,0,          lx<<1,16,8,bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,0);        /* 下部分場圖像的預測 */
		  pred(oldref,mv_field_sel[1][0],cur,1,          lx<<1,16,8,bx,by>>1,PMV[1][0][0],PMV[1][0][1]>>1,0);      }      else if (motion_type==MC_DMV)      {               /* DMV預測 */
        /* 計算衍生的運動向量 */
        calc_DMV(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]>>1);         /* 用上部分場圖像預測上部分場圖像 */
        pred(oldref,0,cur,0,lx<<1,16,8,bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,0);
        /* 用下部分場圖像預測下部分場圖像 */
        pred(oldref,1,cur,1,lx<<1,16,8,bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,0);
        /*用下部分場圖像預測下部分場圖像，并加到原來的場圖像上*/
        pred(oldref,1,cur,0,lx<<1,16,8,bx,by>>1,DMV[0][0],DMV[0][1],1);
        /*用上部分場圖像預測下部分場圖像，并加到原來的場圖像上*/
        pred(oldref,0,cur,1,lx<<1,16,8,bx,by>>1,DMV[1][0],DMV[1][1],1);
      }      else      {         /* 無效的運動類型 */        if (!quiet)          fprintf(stderr,"invalid motion_type\n");      }    }    else /* TOP_FIELD or BOTTOM_FIELD */    {       /* 場圖像 */      currentfield = (pict_struct==BOTTOM_FIELD);   /* 判斷用哪一幀來進行預測*/
      if ((pict_type==P_TYPE) && secondfield          && (currentfield!=mv_field_sel[0][0]))        predframe = newref; /* 同一幀 */      else        predframe = oldref;  /* 前一幀 */      if ((motion_type==MC_FIELD) || !(mb_type & MB_FORWARD))      {        /* 場圖像中基于場的預測*/
		  pred(predframe,mv_field_sel[0][0],cur,currentfield,          lx<<1,16,16,bx,by,PMV[0][0][0],PMV[0][0][1],0);      }      else if (motion_type==MC_16X8)      {           /* 在場圖像中的16×8 運動補償預測*/
        /* 上半部分 */
                pred(predframe,mv_field_sel[0][0],cur,currentfield,          lx<<1,16,8,bx,by,PMV[0][0][0],PMV[0][0][1],0);        /* 判斷用哪一幀圖像來預測下半部分 */
        if ((pict_type==P_TYPE) && secondfield            && (currentfield!=mv_field_sel[1][0]))          predframe = newref; /* same frame */        else          predframe = oldref; /* previous frame */        /* lower half */        pred(predframe,mv_field_sel[1][0],cur,currentfield,          lx<<1,16,8,bx,by+8,PMV[1][0][0],PMV[1][0][1],0);      }      else if (motion_type==MC_DMV)      {         /* DMV預測 */        if (secondfield)          predframe = newref; /* same frame */        else          predframe = oldref; /* previous frame */        calc_DMV(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]);        pred(oldref,currentfield,cur,currentfield,          lx<<1,16,16,bx,by,PMV[0][0][0],PMV[0][0][1],0);        pred(predframe,!currentfield,cur,currentfield,          lx<<1,16,16,bx,by,DMV[0][0],DMV[0][1],1);      }      else      {        if (!quiet)          fprintf(stderr,"invalid motion_type\n");      }    }    addflag = 1; /* 下一個預測值將與該值取平均 */  }  if (mb_type & MB_BACKWARD)  {        /* 后向預測 */    if (pict_struct==FRAME_PICTURE)    {      /* frame picture */      if (motion_type==MC_FRAME)      {        pred(newref,0,cur,0,          lx,16,16,bx,by,PMV[0][1][0],PMV[0][1][1],addflag);      }      else      {               /* top field prediction */        pred(newref,mv_field_sel[0][1],cur,0,          lx<<1,16,8,bx,by>>1,PMV[0][1][0],PMV[0][1][1]>>1,addflag);        /* bottom field prediction */        pred(newref,mv_field_sel[1][1],cur,1,          lx<<1,16,8,bx,by>>1,PMV[1][1][0],PMV[1][1][1]>>1,addflag);      }    }    else /* TOP_FIELD or BOTTOM_FIELD */    {      /* field picture */      currentfield = (pict_struct==BOTTOM_FIELD);      if (motion_type==MC_FIELD)      {        pred(newref,mv_field_sel[0][1],cur,currentfield,          lx<<1,16,16,bx,by,PMV[0][1][0],PMV[0][1][1],addflag);      }      else if (motion_type==MC_16X8)      {        pred(newref,mv_field_sel[0][1],cur,currentfield,          lx<<1,16,8,bx,by,PMV[0][1][0],PMV[0][1][1],addflag);        /* lower half */        pred(newref,mv_field_sel[1][1],cur,currentfield,          lx<<1,16,8,bx,by+8,PMV[1][1][0],PMV[1][1][1],addflag);      }      else      {        /* invalid motion_type in field picture */        if (!quiet)          fprintf(stderr,"invalid motion_type\n");      }    }  }}/* 預測矩形塊
 *
 * src:     源幀(Y,U,V)
 * sfield:  源場選擇(0: 幀或上半場, 1: 下半場)
 * dst:     目標幀(Y,U,V)
 * dfield:  目標場選擇
 *
 * 下面的數值是亮度圖像的參數
 * lx:      相鄰像素的垂直距離
 * w,h:     塊的寬度和高度
 * x,y:     目標塊的坐標
 * dx,dy:   半像素運動向量
 * addflag: 存儲或加預測
 */static void pred(src,sfield,dst,dfield,lx,w,h,x,y,dx,dy,addflag)unsigned char *src[];int sfield;unsigned char *dst[];int dfield;int lx;int w, h;int x, y;int dx, dy;int addflag;{  int cc;  for (cc=0; cc<3; cc++)  {    if (cc==1)    {      /* scale for color components */      if (chroma_format==CHROMA420)      {        /* vertical */        h >>= 1; y >>= 1; dy /= 2;      }      if (chroma_format!=CHROMA444)      {        /* horizontal */        w >>= 1; x >>= 1; dx /= 2;        lx >>= 1;      }    }    pred_comp(src[cc]+(sfield?lx>>1:0),dst[cc]+(dfield?lx>>1:0),      lx,w,h,x,y,dx,dy,addflag);  }}/* 低等級預測
 *
 * src:     源幀(Y,U,V)
 * dst:     目標幀(Y,U,V)
 *
 * lx:      相鄰像素的垂直距離
 * w,h:     塊的寬度和高度
 * x,y:     目標塊的坐標
 * dx,dy:   半像素運動向量
 * addflag: 存儲或加預測
 */
static void pred_comp(src,dst,lx,w,h,x,y,dx,dy,addflag)unsigned char *src;unsigned char *dst;int lx;int w, h;int x, y;int dx, dy;int addflag;{  int xint, xh, yint, yh;  int i, j;  unsigned char *s, *d;  /* half pel scaling */  xint = dx>>1; /* integer part */  xh = dx & 1;  /* half pel flag */  yint = dy>>1;  yh = dy & 1;  /* origins */  s = src + lx*(y+yint) + (x+xint); /* motion vector */  d = dst + lx*y + x;  if (!xh && !yh)    if (addflag)      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (unsigned int)(d[i]+s[i]+1)>>1;        s+= lx;        d+= lx;      }    else      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = s[i];        s+= lx;        d+= lx;      }  else if (!xh && yh)    if (addflag)      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (d[i] + ((unsigned int)(s[i]+s[i+lx]+1)>>1)+1)>>1;        s+= lx;        d+= lx;      }    else      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (unsigned int)(s[i]+s[i+lx]+1)>>1;        s+= lx;        d+= lx;      }  else if (xh && !yh)    if (addflag)      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (d[i] + ((unsigned int)(s[i]+s[i+1]+1)>>1)+1)>>1;        s+= lx;        d+= lx;      }    else      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (unsigned int)(s[i]+s[i+1]+1)>>1;        s+= lx;        d+= lx;      }  else /* if (xh && yh) */    if (addflag)      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (d[i] + ((unsigned int)(s[i]+s[i+1]+s[i+lx]+s[i+lx+1]+2)>>2)+1)>>1;        s+= lx;        d+= lx;      }    else      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)          d[i] = (unsigned int)(s[i]+s[i+1]+s[i+lx]+s[i+lx+1]+2)>>2;        s+= lx;        d+= lx;      }}static void calc_DMV(DMV,dmvector,mvx,mvy)int DMV[][2];int *dmvector;int mvx, mvy;{  if (pict_struct==FRAME_PICTURE)  {    if (topfirst)    {      /* vector for prediction of top field from bottom field */      DMV[0][0] = ((mvx  +(mvx>0))>>1) + dmvector[0];      DMV[0][1] = ((mvy  +(mvy>0))>>1) + dmvector[1] - 1;      /* vector for prediction of bottom field from top field */      DMV[1][0] = ((3*mvx+(mvx>0))>>1) + dmvector[0];      DMV[1][1] = ((3*mvy+(mvy>0))>>1) + dmvector[1] + 1;    }    else    {      /* vector for prediction of top field from bottom field */      DMV[0][0] = ((3*mvx+(mvx>0))>>1) + dmvector[0];      DMV[0][1] = ((3*mvy+(mvy>0))>>1) + dmvector[1] - 1;      /* vector for prediction of bottom field from top field */      DMV[1][0] = ((mvx  +(mvx>0))>>1) + dmvector[0];      DMV[1][1] = ((mvy  +(mvy>0))>>1) + dmvector[1] + 1;    }  }  else  {    /* vector for prediction from field of opposite 'parity' */    DMV[0][0] = ((mvx+(mvx>0))>>1) + dmvector[0];    DMV[0][1] = ((mvy+(mvy>0))>>1) + dmvector[1];    /* correct for vertical field shift */    if (pict_struct==TOP_FIELD)      DMV[0][1]--;    else      DMV[0][1]++;  }}static void clearblock(cur,i0,j0)unsigned char *cur[];int i0, j0;{  int i, j, w, h;  unsigned char *p;  p = cur[0] + ((pict_struct==BOTTOM_FIELD) ? width : 0) + i0 + width2*j0;  for (j=0; j<16; j++)  {    for (i=0; i<16; i++)      p[i] = 128;    p+= width2;  }  w = h = 16;  if (chroma_format!=CHROMA444)  {    i0>>=1; w>>=1;  }  if (chroma_format==CHROMA420)  {    j0>>=1; h>>=1;  }  p = cur[1] + ((pict_struct==BOTTOM_FIELD) ? chrom_width : 0) + i0             + chrom_width2*j0;  for (j=0; j<h; j++)  {    for (i=0; i<w; i++)      p[i] = 128;    p+= chrom_width2;  }  p = cur[2] + ((pict_struct==BOTTOM_FIELD) ? chrom_width : 0) + i0             + chrom_width2*j0;  for (j=0; j<h; j++)  {    for (i=0; i<w; i++)      p[i] = 128;    p+= chrom_width2;  }}