putvlc.c

来自「H.263编解码源代码 目录中存放的是H.263视频编码器和解码器的程序代码。 」· C语言 代码 · 共 117 行

/************************************************************************
 *VLC的编码处理
   
 ************************************************************************/



#include <assert.h>
#include "sim.h"
#include "vlc.h"

int
put_mv (int mvint)
{
  int sign = 0;
  int absmv;

  if (mvint >= 32) {
    absmv = -mvint + 64;
    sign = 1;
  }
  else
    absmv = mvint;
  
  putbits (mvtab[absmv].len, mvtab[absmv].code);

  if (mvint != 0) {
    putbits (1, sign);
    return mvtab[absmv].len + 1;
  }
  else
    return mvtab[absmv].len;
}

int
put_cbpcm_intra (int cbpc, int mode)
{
  int index;

  index = ((mode & 3) >> 1) | ((cbpc & 3) << 2);

  putbits (cbpcm_intra_tab[index].len, cbpcm_intra_tab[index].code);
  
  return cbpcm_intra_tab[index].len;
}

int
put_cbpcm_inter (int cbpc, int mode)
{
  int index;

  index = (mode & 7) | ((cbpc & 3) << 3);

  putbits (cbpcm_inter_tab[index].len, cbpcm_inter_tab[index].code);
  
  return cbpcm_inter_tab[index].len;
}


int
put_cbpy (int cbp, int mode)
{
  int index;

  index = cbp >> 2;

  if (mode < 3)
    index ^= 15;
  
  putbits (cbpy_tab[index].len,	cbpy_tab[index].code);
  
  return cbpy_tab[index].len;
}


int
put_coeff (int run, int level, int last)
{
  int length = 0;
  
  assert (last >= 0 && last < 2);
  assert (run >= 0 && run < 64);
  assert (level > 0 && level < 128);
  
  if (last == 0) {
    if (run < 2 && level < 13 ) {
      putbits (coeff_tab0[run][level-1].len,
	       coeff_tab0[run][level-1].code);

      length = coeff_tab0[run][level-1].len;
    }
    else if (run > 1 && run < 27 && level < 5) {
      putbits (coeff_tab1[run-2][level-1].len,
	       coeff_tab1[run-2][level-1].code);
      
      length = coeff_tab1[run-2][level-1].len;
    }
  }
  else if (last == 1) {
    if (run < 2 && level < 4) {
      putbits (coeff_tab2[run][level-1].len,
	       coeff_tab2[run][level-1].code);
      
      length = coeff_tab2[run][level-1].len;
    }
    else if (run > 1 && run < 42 && level == 1) {
      putbits (coeff_tab3[run-2].len,
	       coeff_tab3[run-2].code);
      
      length = coeff_tab3[run-2].len;
    }
  }
  return length;
}