/* Predict.c, 運動補償程序*/#include <stdio.h>#include "config.h"#include "global.h"/* private prototypes */static void form_prediction _ANSI_ARGS_((unsigned char *src[], int sfield,  unsigned char *dst[], int dfield,  int lx, int lx2, int w, int h, int x, int y, int dx, int dy,  int average_flag));static void form_component_prediction _ANSI_ARGS_((unsigned char *src, unsigned char *dst,  int lx, int lx2, int w, int h, int x, int y, int dx, int dy, int average_flag));void form_predictions(bx,by,macroblock_type,motion_type,PMV,motion_vertical_field_select,dmvector,stwtype)int bx, by;int macroblock_type;int motion_type;int PMV[2][2][2], motion_vertical_field_select[2][2], dmvector[2];int stwtype;{  int currentfield;  unsigned char **predframe;  int DMV[2][2];  int stwtop, stwbot;  stwtop = stwtype%3; /* 0:temporal, 1:(spat+temp)/2, 2:spatial */  stwbot = stwtype/3;  if ((macroblock_type & MACROBLOCK_MOTION_FORWARD)    || (picture_coding_type==P_TYPE))  {    if (picture_structure==FRAME_PICTURE)    {      if ((motion_type==MC_FRAME)         || !(macroblock_type & MACROBLOCK_MOTION_FORWARD))      {        /* frame-based prediction (broken into top and bottom halves             for spatial scalability prediction purposes) */        if (stwtop<2)          form_prediction(forward_reference_frame,0,current_frame,0,            Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,            PMV[0][0][0],PMV[0][0][1],stwtop);        if (stwbot<2)          form_prediction(forward_reference_frame,1,current_frame,1,            Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,            PMV[0][0][0],PMV[0][0][1],stwbot);      }      else if (motion_type==MC_FIELD) /* field-based prediction */      {        /* top field prediction */        if (stwtop<2)          form_prediction(forward_reference_frame,motion_vertical_field_select[0][0],            current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,            bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,stwtop);        /* bottom field prediction */        if (stwbot<2)          form_prediction(forward_reference_frame,motion_vertical_field_select[1][0],            current_frame,1,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,            bx,by>>1,PMV[1][0][0],PMV[1][0][1]>>1,stwbot);      }      else if (motion_type==MC_DMV) /* dual prime prediction */      {        /* calculate derived motion vectors */        Dual_Prime_Arithmetic(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]>>1);        if (stwtop<2)        {          /* predict top field from top field */          form_prediction(forward_reference_frame,0,current_frame,0,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,            PMV[0][0][0],PMV[0][0][1]>>1,0);          /* predict and add to top field from bottom field */          form_prediction(forward_reference_frame,1,current_frame,0,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,            DMV[0][0],DMV[0][1],1);        }        if (stwbot<2)        {          /* predict bottom field from bottom field */          form_prediction(forward_reference_frame,1,current_frame,1,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,            PMV[0][0][0],PMV[0][0][1]>>1,0);          /* predict and add to bottom field from top field */          form_prediction(forward_reference_frame,0,current_frame,1,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by>>1,            DMV[1][0],DMV[1][1],1);        }      }      else        /* invalid motion_type */        printf("invalid motion_type\n");    }    else /* TOP_FIELD or BOTTOM_FIELD */    {      /* field picture */      currentfield = (picture_structure==BOTTOM_FIELD);      /* determine which frame to use for prediction */      if ((picture_coding_type==P_TYPE) && Second_Field         && (currentfield!=motion_vertical_field_select[0][0]))        predframe = backward_reference_frame; /* same frame */      else        predframe = forward_reference_frame; /* previous frame */      if ((motion_type==MC_FIELD)        || !(macroblock_type & MACROBLOCK_MOTION_FORWARD))      {        /* field-based prediction */        if (stwtop<2)          form_prediction(predframe,motion_vertical_field_select[0][0],current_frame,0,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,            PMV[0][0][0],PMV[0][0][1],stwtop);      }      else if (motion_type==MC_16X8)      {        if (stwtop<2)        {          form_prediction(predframe,motion_vertical_field_select[0][0],current_frame,0,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by,            PMV[0][0][0],PMV[0][0][1],stwtop);          /* determine which frame to use for lower half prediction */          if ((picture_coding_type==P_TYPE) && Second_Field             && (currentfield!=motion_vertical_field_select[1][0]))            predframe = backward_reference_frame; /* same frame */          else            predframe = forward_reference_frame; /* previous frame */          form_prediction(predframe,motion_vertical_field_select[1][0],current_frame,0,            Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,bx,by+8,            PMV[1][0][0],PMV[1][0][1],stwtop);        }      }      else if (motion_type==MC_DMV) /* dual prime prediction */      {        if (Second_Field)          predframe = backward_reference_frame; /* same frame */        else          predframe = forward_reference_frame; /* previous frame */        /* calculate derived motion vectors */        Dual_Prime_Arithmetic(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]);        /* predict from field of same parity */        form_prediction(forward_reference_frame,currentfield,current_frame,0,          Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,          PMV[0][0][0],PMV[0][0][1],0);        /* predict from field of opposite parity */        form_prediction(predframe,!currentfield,current_frame,0,          Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,bx,by,          DMV[0][0],DMV[0][1],1);      }      else        /* invalid motion_type */        printf("invalid motion_type\n");    }    stwtop = stwbot = 1;  }  if (macroblock_type & MACROBLOCK_MOTION_BACKWARD)  {    if (picture_structure==FRAME_PICTURE)    {      if (motion_type==MC_FRAME)      {        /* frame-based prediction */        if (stwtop<2)          form_prediction(backward_reference_frame,0,current_frame,0,            Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,            PMV[0][1][0],PMV[0][1][1],stwtop);        if (stwbot<2)          form_prediction(backward_reference_frame,1,current_frame,1,            Coded_Picture_Width,Coded_Picture_Width<<1,16,8,bx,by,            PMV[0][1][0],PMV[0][1][1],stwbot);      }      else /* field-based prediction */      {        /* top field prediction */        if (stwtop<2)          form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],            current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,            bx,by>>1,PMV[0][1][0],PMV[0][1][1]>>1,stwtop);        /* bottom field prediction */        if (stwbot<2)          form_prediction(backward_reference_frame,motion_vertical_field_select[1][1],            current_frame,1,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,            bx,by>>1,PMV[1][1][0],PMV[1][1][1]>>1,stwbot);      }    }    else /* TOP_FIELD or BOTTOM_FIELD */    {      /* field picture */      if (motion_type==MC_FIELD)      {        /* field-based prediction */        form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],          current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,16,          bx,by,PMV[0][1][0],PMV[0][1][1],stwtop);      }      else if (motion_type==MC_16X8)      {        form_prediction(backward_reference_frame,motion_vertical_field_select[0][1],          current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,          bx,by,PMV[0][1][0],PMV[0][1][1],stwtop);        form_prediction(backward_reference_frame,motion_vertical_field_select[1][1],          current_frame,0,Coded_Picture_Width<<1,Coded_Picture_Width<<1,16,8,          bx,by+8,PMV[1][1][0],PMV[1][1][1],stwtop);      }      else        /* invalid motion_type */        printf("invalid motion_type\n");    }  }}static void form_prediction(src,sfield,dst,dfield,lx,lx2,w,h,x,y,dx,dy,average_flag)unsigned char *src[]; /* prediction source buffer */int sfield;           /* prediction source field number (0 or 1) */unsigned char *dst[]; /* prediction destination buffer */int dfield;           /* prediction destination field number (0 or 1)*/int lx,lx2;           /* line strides */int w,h;              /* prediction block/sub-block width, height */int x,y;              /* pixel co-ordinates of top-left sample in current MB */int dx,dy;            /* horizontal, vertical prediction address */int average_flag;     /* add prediction error to prediction ? */{  /* Y */  form_component_prediction(src[0]+(sfield?lx2>>1:0),dst[0]+(dfield?lx2>>1:0),    lx,lx2,w,h,x,y,dx,dy,average_flag);  if (chroma_format!=CHROMA444)  {    lx>>=1; lx2>>=1; w>>=1; x>>=1; dx/=2;  }  if (chroma_format==CHROMA420)  {    h>>=1; y>>=1; dy/=2;  }  /* Cb */  form_component_prediction(src[1]+(sfield?lx2>>1:0),dst[1]+(dfield?lx2>>1:0),    lx,lx2,w,h,x,y,dx,dy,average_flag);  /* Cr */  form_component_prediction(src[2]+(sfield?lx2>>1:0),dst[2]+(dfield?lx2>>1:0),    lx,lx2,w,h,x,y,dx,dy,average_flag);}/* ISO/IEC 13818-2 section 7.6.4: Forming predictions *//* NOTE: the arithmetic below produces numerically equivalent results *  to 7.6.4, yet is more elegant. It differs in the following ways: * *   1. the vectors (dx, dy) are based on cartesian frame  *      coordiantes along a half-pel grid (always positive numbers) *      In contrast, vector[r][s][t] are differential (with positive and  *      negative values). As a result, deriving the integer vectors  *      (int_vec[t]) from dx, dy is accomplished by a simple right shift. * *   2. Half pel flags (xh, yh) are equivalent to the LSB (Least *      Significant Bit) of the half-pel coordinates (dx,dy). *  * *  NOTE: the work of combining predictions (ISO/IEC 13818-2 section 7.6.7) *  is distributed among several other stages.  This is accomplished by  *  folding line offsets into the source and destination (src,dst) *  addresses (note the call arguments to form_prediction() in Predict()), *  line stride variables lx and lx2, the block dimension variables (w,h),  *  average_flag, and by the very order in which Predict() is called.   *  This implementation design (implicitly different than the spec)  *  was chosen for its elegance.*/static void form_component_prediction(src,dst,lx,lx2,w,h,x,y,dx,dy,average_flag)unsigned char *src;unsigned char *dst;int lx;          /* raster line increment */ int lx2;int w,h;int x,y;int dx,dy;int average_flag;      /* flag that signals bi-directional or Dual-Prime                           averaging (7.6.7.1 and 7.6.7.4). if average_flag==1,                          a previously formed prediction has been stored in                           pel_pred[] */{  int xint;      /* horizontal integer sample vector: analogous to int_vec[0] */  int yint;      /* vertical integer sample vectors: analogous to int_vec[1] */  int xh;        /* horizontal half sample flag: analogous to half_flag[0]  */  int yh;        /* vertical half sample flag: analogous to half_flag[1]  */  int i, j, v;  unsigned char *s;    /* source pointer: analogous to pel_ref[][]   */  unsigned char *d;    /* destination pointer:  analogous to pel_pred[][]  */  /* half pel scaling for integer vectors */  xint = dx>>1;  yint = dy>>1;  /* derive half pel flags */  xh = dx & 1;  yh = dy & 1;  /* compute the linear address of pel_ref[][] and pel_pred[][]      based on cartesian/raster cordinates provided */  s = src + lx*(y+yint) + x + xint;  d = dst + lx*y + x;  if (!xh && !yh) /* no horizontal nor vertical half-pel */  {    if (average_flag)    {      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)        {          v = d[i]+s[i];          d[i] = (v+(v>=0?1:0))>>1;        }              s+= lx2;        d+= lx2;      }    }    else    {      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)        {          d[i] = s[i];        }                s+= lx2;        d+= lx2;      }    }  }  else if (!xh && yh) /* no horizontal but vertical half-pel */  {    if (average_flag)    {      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)        {          v = d[i] + ((unsigned int)(s[i]+s[i+lx]+1)>>1);          d[i]=(v+(v>=0?1:0))>>1;        }             s+= lx2;        d+= lx2;      }    }    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+= lx2;        d+= lx2;      }    }  }  else if (xh && !yh) /* horizontal but no vertical half-pel */  {    if (average_flag)    {      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)        {          v = d[i] + ((unsigned int)(s[i]+s[i+1]+1)>>1);          d[i] = (v+(v>=0?1:0))>>1;        }             s+= lx2;        d+= lx2;      }    }    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+= lx2;        d+= lx2;      }    }  }  else /* if (xh && yh) horizontal and vertical half-pel */  {    if (average_flag)    {      for (j=0; j<h; j++)      {        for (i=0; i<w; i++)        {          v = d[i] + ((unsigned int)(s[i]+s[i+1]+s[i+lx]+s[i+lx+1]+2)>>2);          d[i] = (v+(v>=0?1:0))>>1;        }             s+= lx2;        d+= lx2;      }    }    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+= lx2;        d+= lx2;      }    }  }}