/* motion.c, motion vector 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 decode_motion_vector _ANSI_ARGS_((int *pred, int r_size, int motion_code,  int motion_residualesidual, int full_pel_vector));/* ISO/IEC 13818-2 sections 6.2.5.2, 6.3.17.2, and 7.6.3: Motion vectors */void motion_vectors(PMV,dmvector,  motion_vertical_field_select,s,motion_vector_count,mv_format,h_r_size,v_r_size,dmv,mvscale)int PMV[2][2][2];int dmvector[2];int motion_vertical_field_select[2][2];int s, motion_vector_count, mv_format, h_r_size, v_r_size, dmv, mvscale;{  if (motion_vector_count==1)  {    if (mv_format==MV_FIELD && !dmv)    {      motion_vertical_field_select[1][s] = motion_vertical_field_select[0][s] = Get_Bits(1);#ifdef TRACE      if (Trace_Flag)      {        printf("motion_vertical_field_select[][%d] (%d): %d\n",s,          motion_vertical_field_select[0][s],motion_vertical_field_select[0][s]);      }#endif /* TRACE */    }    motion_vector(PMV[0][s],dmvector,h_r_size,v_r_size,dmv,mvscale,0);    /* update other motion vector predictors */    PMV[1][s][0] = PMV[0][s][0];    PMV[1][s][1] = PMV[0][s][1];  }  else  {    motion_vertical_field_select[0][s] = Get_Bits(1);#ifdef TRACE    if (Trace_Flag)    {      printf("motion_vertical_field_select[0][%d] (%d): %d\n",s,        motion_vertical_field_select[0][s],motion_vertical_field_select[0][s]);    }#endif /* TRACE */    motion_vector(PMV[0][s],dmvector,h_r_size,v_r_size,dmv,mvscale,0);    motion_vertical_field_select[1][s] = Get_Bits(1);#ifdef TRACE    if (Trace_Flag)    {      printf("motion_vertical_field_select[1][%d] (%d): %d\n",s,        motion_vertical_field_select[1][s],motion_vertical_field_select[1][s]);    }#endif /* TRACE */    motion_vector(PMV[1][s],dmvector,h_r_size,v_r_size,dmv,mvscale,0);  }}/* get and decode motion vector and differential motion vector    for one prediction */void motion_vector(PMV,dmvector,  h_r_size,v_r_size,dmv,mvscale,full_pel_vector)int *PMV;int *dmvector;int h_r_size;int v_r_size;int dmv; /* MPEG-2 only: get differential motion vectors */int mvscale; /* MPEG-2 only: field vector in frame pic */int full_pel_vector; /* MPEG-1 only */{  int motion_code, motion_residual;  /* horizontal component */  /* ISO/IEC 13818-2 Table B-10 */  motion_code = Get_motion_code();  motion_residual = (h_r_size!=0 && motion_code!=0) ? Get_Bits(h_r_size) : 0;#ifdef TRACE  if (Trace_Flag)  {    if (h_r_size!=0 && motion_code!=0)    {      printf("motion_residual (");      Print_Bits(motion_residual,h_r_size,h_r_size);      printf("): %d\n",motion_residual);    }  }#endif /* TRACE */  decode_motion_vector(&PMV[0],h_r_size,motion_code,motion_residual,full_pel_vector);  if (dmv)    dmvector[0] = Get_dmvector();  /* vertical component */  motion_code     = Get_motion_code();  motion_residual = (v_r_size!=0 && motion_code!=0) ? Get_Bits(v_r_size) : 0;#ifdef TRACE  if (Trace_Flag)  {    if (v_r_size!=0 && motion_code!=0)    {      printf("motion_residual (");      Print_Bits(motion_residual,v_r_size,v_r_size);      printf("): %d\n",motion_residual);    }  }#endif /* TRACE */  if (mvscale)    PMV[1] >>= 1; /* DIV 2 */  decode_motion_vector(&PMV[1],v_r_size,motion_code,motion_residual,full_pel_vector);  if (mvscale)    PMV[1] <<= 1;  if (dmv)    dmvector[1] = Get_dmvector();#ifdef TRACE  if (Trace_Flag)    printf("PMV = %d,%d\n",PMV[0],PMV[1]);#endif /* TRACE */}/* calculate motion vector component *//* ISO/IEC 13818-2 section 7.6.3.1: Decoding the motion vectors *//* Note: the arithmetic here is more elegant than that which is shown    in 7.6.3.1.  The end results (PMV[][][]) should, however, be the same.  */static void decode_motion_vector(pred,r_size,motion_code,motion_residual,full_pel_vector)int *pred;int r_size, motion_code, motion_residual;int full_pel_vector; /* MPEG-1 (ISO/IEC 11172-1) support */{  int lim, vec;  lim = 16<<r_size;  vec = full_pel_vector ? (*pred >> 1) : (*pred);  if (motion_code>0)  {    vec+= ((motion_code-1)<<r_size) + motion_residual + 1;    if (vec>=lim)      vec-= lim + lim;  }  else if (motion_code<0)  {    vec-= ((-motion_code-1)<<r_size) + motion_residual + 1;    if (vec<-lim)      vec+= lim + lim;  }  *pred = full_pel_vector ? (vec<<1) : vec;}/* ISO/IEC 13818-2 section 7.6.3.6: Dual prime additional arithmetic */void Dual_Prime_Arithmetic(DMV,dmvector,mvx,mvy)int DMV[][2];int *dmvector; /* differential motion vector */int mvx, mvy;  /* decoded mv components (always in field format) */{  if (picture_structure==FRAME_PICTURE)  {    if (top_field_first)    {      /* 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 (picture_structure==TOP_FIELD)      DMV[0][1]--;    else      DMV[0][1]++;  }}