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putmpg.C

/* putmpg.c, block and motion vector encoding routines                      */

/* 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"

/* generate variable length codes for an intra-coded block (6.2.6, 6.3.17) */
void MPEG::putintrablk(short *blk, int cc)
{
      int n, dct_diff, run, signed_level;

      /* DC coefficient (7.2.1) */
      dct_diff = blk[0] - dc_dct_pred[cc]; /* difference to previous block */
      dc_dct_pred[cc] = blk[0];

      if (cc==0)
            putDClum(dct_diff);
      else
            putDCchrom(dct_diff);

      /* AC coefficients (7.2.2) */
      run = 0;
      for (n=1; n<64; n++)
      {
            /* use appropriate entropy scanning pattern */
            signed_level = blk[(altscan ? alternate_scan : zig_zag_scan)[n]];
            if (signed_level!=0)
            {
                  putAC(run,signed_level,intravlc);
                  run = 0;
            }
            else
                  run++; /* count zero coefficients */
      }

      /* End of Block -- normative block punctuation */
      if (intravlc)
            putbits(6,4); /* 0110 (Table B-15) */
      else
            putbits(2,2); /* 10 (Table B-14) */
}

/* generate variable length codes for a non-intra-coded block (6.2.6, 6.3.17) */
void MPEG::putnonintrablk(short *blk)
{
      int n, run, signed_level, first;

      run = 0;
      first = 1;

      for (n=0; n<64; n++)
      {
            /* use appropriate entropy scanning pattern */
            signed_level = blk[(altscan ? alternate_scan : zig_zag_scan)[n]];

            if (signed_level!=0)
            {
                  if (first)
                  {
                        /* first coefficient in non-intra block */
                        putACfirst(run,signed_level);
                        first = 0;
                  }
                  else
                        putAC(run,signed_level,0);

                  run = 0;
            }
            else
                  run++; /* count zero coefficients */
      }

      /* End of Block -- normative block punctuation  */
      putbits(2,2);
}

/* generate variable length code for a motion vector component (7.6.3.1) */
void MPEG::putmv(int dmv, int f_code)
{
      int r_size, f, vmin, vmax, dv, temp, motion_code, motion_residual;

      r_size = f_code - 1; /* number of fixed length code ('residual') bits */
      f = 1<<r_size;
      vmin = -16*f; /* lower range limit */
      vmax = 16*f - 1; /* upper range limit */
      dv = 32*f;

      /* fold vector difference into [vmin...vmax] */
      if (dmv>vmax)
            dmv-= dv;
      else if (dmv<vmin)
            dmv+= dv;

      /* check value */
      if (dmv<vmin || dmv>vmax)
            if (!quiet)
                  fprintf(stderr,"invalid motion vector\n");

      /* split dmv into motion_code and motion_residual */
      temp = ((dmv<0) ? -dmv : dmv) + f - 1;
      motion_code = temp>>r_size;
      if (dmv<0)
            motion_code = -motion_code;
      motion_residual = temp & (f-1);

      putmotioncode(motion_code); /* variable length code */

      if (r_size!=0 && motion_code!=0)
            putbits(motion_residual,r_size); /* fixed length code */
}

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