Logo Search packages:      
Sourcecode: tela version File versions  Download package

predict.C

/* predict.c, motion compensated prediction                                 */

/* 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 "mpegintf.H"
#include "global.h"

/* private prototypes */
static void pred_comp(unsigned char *src, unsigned char *dst,
  int lx, int w, int h, int x, int y, int dx, int dy, int addflag);


/* form prediction for a complete picture (frontend for predict_mb)
 *
 * reff: reference frame for forward prediction
 * refb: reference frame for backward prediction
 * cur:  destination (current) frame
 * secondfield: predict second field of a frame
 * mbi:  macroblock info
 *
 * Notes:
 * - cf. predict_mb
 */

void MPEG::predict(unsigned char *reff[], unsigned char *refb[], unsigned char *cur[3],
                           int secondfield, Tmbinfo *mbi)
{
      int i, j, k;

      k = 0;

      /* loop through all macroblocks of the picture */
      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++;
            }
}

/* form prediction for one macroblock
 *
 * oldref: reference frame for forward prediction
 * newref: reference frame for backward prediction
 * cur:    destination (current) frame
 * lx:     frame width (identical to global var `width')
 * bx,by:  picture (field or frame) coordinates of macroblock to be predicted
 * pict_type: I, P or B
 * pict_struct: FRAME_PICTURE, TOP_FIELD, BOTTOM_FIELD
 * mb_type:     MB_FORWARD, MB_BACKWARD, MB_INTRA
 * motion_type: MC_FRAME, MC_FIELD, MC_16X8, MC_DMV
 * secondfield: predict second field of a frame
 * PMV[2][2][2]: motion vectors (in half pel picture coordinates)
 * mv_field_sel[2][2]: motion vertical field selects (for field predictions)
 * dmvector: differential motion vectors (for dual prime)
 *
 * Notes:
 * - when predicting a P type picture which is the second field of
 *   a frame, the same parity reference field is in oldref, while the
 *   opposite parity reference field is assumed to be in newref!
 * - intra macroblocks are modelled to have a constant prediction of 128
 *   for all pels; this results in a DC DCT coefficient symmetric to 0
 * - vectors for field prediction in frame pictures are in half pel frame
 *   coordinates (vertical component is twice the field value and always
 *   even)
 *
 * already covers dual prime (not yet used)
 */

void MPEG::predict_mb(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])
{
      int addflag, currentfield;
      unsigned char **predframe;
      int DMV[2][2];

      if (mb_type&MB_INTRA)
      {
            clearblock(cur,bx,by);
            return;
      }

      addflag = 0; /* first prediction is stored, second is added and averaged */

      if ((mb_type & MB_FORWARD) || (pict_type==P_TYPE))
      {
            /* forward prediction, including zero MV in P pictures */

            if (pict_struct==FRAME_PICTURE)
            {
                  /* frame picture */

                  if ((motion_type==MC_FRAME) || !(mb_type & MB_FORWARD))
                  {
                        /* frame-based prediction in frame picture */
                        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)
                  {
                        /* field-based prediction in frame picture
                         *
                         * note scaling of the vertical coordinates (by, PMV[][0][1])
                         * from frame to field!
                         */

                        /* top field prediction */
                        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);

                        /* bottom field prediction */
                        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)
                  {
                        /* dual prime prediction */

                        /* calculate derived motion vectors */
                        calc_DMV(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]>>1);

                        /* predict top field from top field */
                        pred(oldref,0,cur,0,
                               lx<<1,16,8,bx,by>>1,PMV[0][0][0],PMV[0][0][1]>>1,0);

                        /* predict bottom field from bottom field */
                        pred(oldref,1,cur,1,
                               lx<<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 */
                        pred(oldref,1,cur,0,
                               lx<<1,16,8,bx,by>>1,DMV[0][0],DMV[0][1],1);

                        /* predict and add to bottom field from top field */
                        pred(oldref,0,cur,1,
                               lx<<1,16,8,bx,by>>1,DMV[1][0],DMV[1][1],1);
                  }
                  else
                  {
                        /* invalid motion_type in frame picture */
                        if (!quiet)
                              fprintf(stderr,"invalid motion_type\n");
                  }
            }
            else /* TOP_FIELD or BOTTOM_FIELD */
            {
                  /* field picture */

                  currentfield = (pict_struct==BOTTOM_FIELD);

                  /* determine which frame to use for prediction */
                  if ((pict_type==P_TYPE) && secondfield
                        && (currentfield!=mv_field_sel[0][0]))
                        predframe = newref; /* same frame */
                  else
                        predframe = oldref; /* previous frame */

                  if ((motion_type==MC_FIELD) || !(mb_type & MB_FORWARD))
                  {
                        /* field-based prediction in field picture */
                        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)
                  {
                        /* 16 x 8 motion compensation in field picture */

                        /* upper half */
                        pred(predframe,mv_field_sel[0][0],cur,currentfield,
                               lx<<1,16,8,bx,by,PMV[0][0][0],PMV[0][0][1],0);

                        /* determine which frame to use for lower half prediction */
                        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)
                  {
                        /* dual prime prediction */

                        /* determine which frame to use for prediction */
                        if (secondfield)
                              predframe = newref; /* same frame */
                        else
                              predframe = oldref; /* previous frame */

                        /* calculate derived motion vectors */
                        calc_DMV(DMV,dmvector,PMV[0][0][0],PMV[0][0][1]);

                        /* predict from field of same parity */
                        pred(oldref,currentfield,cur,currentfield,
                               lx<<1,16,16,bx,by,PMV[0][0][0],PMV[0][0][1],0);

                        /* predict from field of opposite parity */
                        pred(predframe,!currentfield,cur,currentfield,
                               lx<<1,16,16,bx,by,DMV[0][0],DMV[0][1],1);
                  }
                  else
                  {
                        /* invalid motion_type in field picture */
                        if (!quiet)
                              fprintf(stderr,"invalid motion_type\n");
                  }
            }
            addflag = 1; /* next prediction (if any) will be averaged with this one */
      }

      if (mb_type & MB_BACKWARD)
      {
            /* backward prediction */

            if (pict_struct==FRAME_PICTURE)
            {
                  /* frame picture */

                  if (motion_type==MC_FRAME)
                  {
                        /* frame-based prediction in frame picture */
                        pred(newref,0,cur,0,
                               lx,16,16,bx,by,PMV[0][1][0],PMV[0][1][1],addflag);
                  }
                  else
                  {
                        /* field-based prediction in frame picture
                         *
                         * note scaling of the vertical coordinates (by, PMV[][1][1])
                         * from frame to field!
                         */

                        /* 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)
                  {
                        /* field-based prediction in field picture */
                        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)
                  {
                        /* 16 x 8 motion compensation in field picture */

                        /* upper half */
                        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");
                  }
            }
      }
}

/* predict a rectangular block (all three components)
 *
 * src:     source frame (Y,U,V)
 * sfield:  source field select (0: frame or top field, 1: bottom field)
 * dst:     destination frame (Y,U,V)
 * dfield:  destination field select (0: frame or top field, 1: bottom field)
 *
 * the following values are in luminance picture (frame or field) dimensions
 * lx:      distance of vertically adjacent pels (selects frame or field pred.)
 * w,h:     width and height of block (only 16x16 or 16x8 are used)
 * x,y:     coordinates of destination block
 * dx,dy:   half pel motion vector
 * addflag: store or add (= average) prediction
 */
void MPEG::pred(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)
{
      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);
      }
}

/* low level prediction routine
 *
 * src:     prediction source
 * dst:     prediction destination
 * lx:      line width (for both src and dst)
 * x,y:     destination coordinates
 * dx,dy:   half pel motion vector
 * w,h:     size of prediction block
 * addflag: store or add prediction
 */

static void pred_comp(unsigned char *src, unsigned char *dst,
                                int lx, int w, int h, int x, int y, int dx, int 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;
                  }
}


/* calculate derived motion vectors (DMV) for dual prime prediction
 * dmvector[2]: differential motion vectors (-1,0,+1)
 * mvx,mvy: motion vector (for same parity)
 *
 * DMV[2][2]: derived motion vectors (for opposite parity)
 *
 * uses global variables pict_struct and topfirst
 *
 * Notes:
 *  - all vectors are in field coordinates (even for frame pictures)
 */

void MPEG::calc_DMV(int DMV[][2], int *dmvector, int mvx, int 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]++;
      }
}

void MPEG::clearblock(unsigned char *cur[], int i0, int 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;
      }
}

Generated by  Doxygen 1.6.0   Back to index