vlc.c

H.264编码实现

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    write VLC for TotalZeros
 ************************************************************************
 */
int writeSyntaxElement_TotalZeros(SyntaxElement *se, DataPartition *dp)
{
  static const int lentab[TOTRUN_NUM][16] =
  {
    { 1,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9},
    { 3,3,3,3,3,4,4,4,4,5,5,6,6,6,6},
    { 4,3,3,3,4,4,3,3,4,5,5,6,5,6},
    { 5,3,4,4,3,3,3,4,3,4,5,5,5},
    { 4,4,4,3,3,3,3,3,4,5,4,5},
    { 6,5,3,3,3,3,3,3,4,3,6},
    { 6,5,3,3,3,2,3,4,3,6},
    { 6,4,5,3,2,2,3,3,6},
    { 6,6,4,2,2,3,2,5},
    { 5,5,3,2,2,2,4},
    { 4,4,3,3,1,3},
    { 4,4,2,1,3},
    { 3,3,1,2},
    { 2,2,1},
    { 1,1},
  };

  static const int codtab[TOTRUN_NUM][16] =
  {
    {1,3,2,3,2,3,2,3,2,3,2,3,2,3,2,1},
    {7,6,5,4,3,5,4,3,2,3,2,3,2,1,0},
    {5,7,6,5,4,3,4,3,2,3,2,1,1,0},
    {3,7,5,4,6,5,4,3,3,2,2,1,0},
    {5,4,3,7,6,5,4,3,2,1,1,0},
    {1,1,7,6,5,4,3,2,1,1,0},
    {1,1,5,4,3,3,2,1,1,0},
    {1,1,1,3,3,2,2,1,0},
    {1,0,1,3,2,1,1,1,},
    {1,0,1,3,2,1,1,},
    {0,1,1,2,1,3},
    {0,1,1,1,1},
    {0,1,1,1},
    {0,1,1},
    {0,1},
  };
  int vlcnum = se->len;

  // se->value1 : TotalZeros
  se->len = lentab[vlcnum][se->value1];
  se->inf = codtab[vlcnum][se->value1];

  if (se->len == 0)
  {
    printf("ERROR: (TotalZeros) not valid: (%d)\n",se->value1);
    exit(-1);
  }

  symbol2vlc(se);

  writeUVLC2buffer(se, dp->bitstream);

  if(se->type != SE_HEADER)
    dp->bitstream->write_flag = 1;

#if TRACE
  if(dp->bitstream->trace_enabled)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    write VLC for TotalZeros for Chroma DC
 ************************************************************************
 */
int writeSyntaxElement_TotalZerosChromaDC(SyntaxElement *se, DataPartition *dp)
{
  static const int lentab[3][TOTRUN_NUM][16] =
  {
    //YUV420
   {{ 1,2,3,3},
    { 1,2,2},
    { 1,1}},
    //YUV422
   {{ 1,3,3,4,4,4,5,5},
    { 3,2,3,3,3,3,3},
    { 3,3,2,2,3,3},
    { 3,2,2,2,3},
    { 2,2,2,2},
    { 2,2,1},
    { 1,1}},
    //YUV444
   {{ 1,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9},
    { 3,3,3,3,3,4,4,4,4,5,5,6,6,6,6},
    { 4,3,3,3,4,4,3,3,4,5,5,6,5,6},
    { 5,3,4,4,3,3,3,4,3,4,5,5,5},
    { 4,4,4,3,3,3,3,3,4,5,4,5},
    { 6,5,3,3,3,3,3,3,4,3,6},
    { 6,5,3,3,3,2,3,4,3,6},
    { 6,4,5,3,2,2,3,3,6},
    { 6,6,4,2,2,3,2,5},
    { 5,5,3,2,2,2,4},
    { 4,4,3,3,1,3},
    { 4,4,2,1,3},
    { 3,3,1,2},
    { 2,2,1},
    { 1,1}}
  };

  static const int codtab[3][TOTRUN_NUM][16] =
  {
    //YUV420
   {{ 1,1,1,0},
    { 1,1,0},
    { 1,0}},
    //YUV422
   {{ 1,2,3,2,3,1,1,0},
    { 0,1,1,4,5,6,7},
    { 0,1,1,2,6,7},
    { 6,0,1,2,7},
    { 0,1,2,3},
    { 0,1,1},
    { 0,1}},
    //YUV444
   {{1,3,2,3,2,3,2,3,2,3,2,3,2,3,2,1},
    {7,6,5,4,3,5,4,3,2,3,2,3,2,1,0},
    {5,7,6,5,4,3,4,3,2,3,2,1,1,0},
    {3,7,5,4,6,5,4,3,3,2,2,1,0},
    {5,4,3,7,6,5,4,3,2,1,1,0},
    {1,1,7,6,5,4,3,2,1,1,0},
    {1,1,5,4,3,3,2,1,1,0},
    {1,1,1,3,3,2,2,1,0},
    {1,0,1,3,2,1,1,1,},
    {1,0,1,3,2,1,1,},
    {0,1,1,2,1,3},
    {0,1,1,1,1},
    {0,1,1,1},
    {0,1,1},
    {0,1}}
  };
  int vlcnum = se->len;
  int yuv = img->yuv_format - 1;  

  // se->value1 : TotalZeros
  se->len = lentab[yuv][vlcnum][se->value1];
  se->inf = codtab[yuv][vlcnum][se->value1];

  if (se->len == 0)
  {
    printf("ERROR: (TotalZeros) not valid: (%d)\n",se->value1);
    exit(-1);
  }

  symbol2vlc(se);

  writeUVLC2buffer(se, dp->bitstream);

  if(se->type != SE_HEADER)
    dp->bitstream->write_flag = 1;

#if TRACE
  if(dp->bitstream->trace_enabled)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    write VLC for Run Before Next Coefficient, VLC0
 ************************************************************************
 */
int writeSyntaxElement_Run(SyntaxElement *se, DataPartition *dp)
{
  static const int lentab[TOTRUN_NUM][16] =
  {
    {1,1},
    {1,2,2},
    {2,2,2,2},
    {2,2,2,3,3},
    {2,2,3,3,3,3},
    {2,3,3,3,3,3,3},
    {3,3,3,3,3,3,3,4,5,6,7,8,9,10,11},
  };

  static const int codtab[TOTRUN_NUM][16] =
  {
    {1,0},
    {1,1,0},
    {3,2,1,0},
    {3,2,1,1,0},
    {3,2,3,2,1,0},
    {3,0,1,3,2,5,4},
    {7,6,5,4,3,2,1,1,1,1,1,1,1,1,1},
  };
  int vlcnum = se->len;

  // se->value1 : run
  se->len = lentab[vlcnum][se->value1];
  se->inf = codtab[vlcnum][se->value1];

  if (se->len == 0)
  {
    printf("ERROR: (run) not valid: (%d)\n",se->value1);
    exit(-1);
  }

  symbol2vlc(se);

  writeUVLC2buffer(se, dp->bitstream);

  if(se->type != SE_HEADER)
    dp->bitstream->write_flag = 1;

#if TRACE
  if(dp->bitstream->trace_enabled)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    write VLC for Coeff Level (VLC1)
 ************************************************************************
 */
int writeSyntaxElement_Level_VLC1(SyntaxElement *se, DataPartition *dp, int profile_idc)
{
  int level  = se->value1;
  int sign   = (level < 0 ? 1 : 0);
  int levabs = iabs(level);

  if (levabs < 8)
  {
    se->len = levabs * 2 + sign - 1;
    se->inf = 1;
  }
  else if (levabs < 16) 
  {
    // escape code1
    se->len = 19;
    se->inf = 16 | ((levabs << 1) - 16) | sign;
  }
  else
  {
    int iMask = 4096, numPrefix = 0;
    int levabsm16 = levabs + 2032;

    // escape code2
    if ((levabsm16) >= 4096)
    {
      numPrefix++;
      while ((levabsm16) >= (4096 << numPrefix))
      {
        numPrefix++;
      }
    }
   
    iMask <<= numPrefix;
    se->inf = iMask | ((levabsm16 << 1) - iMask) | sign;

    /* Assert to make sure that the code fits in the VLC */
    /* make sure that we are in High Profile to represent level_prefix > 15 */
    if (numPrefix > 0 && !IS_FREXT_PROFILE( profile_idc ))
    {
      //error( "level_prefix must be <= 15 except in High Profile\n",  1000 );
      se->len = 0x0000FFFF; // This can be some other big number
      return (se->len);
    }
    
    se->len = 28 + (numPrefix << 1);
  }


  symbol2vlc(se);

  writeUVLC2buffer(se, dp->bitstream);

  if(se->type != SE_HEADER)
    dp->bitstream->write_flag = 1;

#if TRACE
  if(dp->bitstream->trace_enabled)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    write VLC for Coeff Level
 ************************************************************************
 */
int writeSyntaxElement_Level_VLCN(SyntaxElement *se, int vlc, DataPartition *dp, int profile_idc)
{  
  int level  = se->value1;
  int sign   = (level < 0 ? 1 : 0);
  int levabs = iabs(level) - 1;  

  int shift = vlc - 1;        
  int escape = (15 << shift);

  if (levabs < escape)
  {
    int sufmask   = ~((0xffffffff) << shift);
    int suffix    = (levabs) & sufmask;

    se->len = ((levabs) >> shift) + 1 + vlc;
    se->inf = (2 << shift) | (suffix << 1) | sign;
  }
  else
  {
    int iMask = 4096;
    int levabsesc = levabs - escape + 2048;
    int numPrefix = 0;

    if ((levabsesc) >= 4096)
    {
      numPrefix++;
      while ((levabsesc) >= (4096 << numPrefix))
      {
        numPrefix++;
      }
    }

    iMask <<= numPrefix;
    se->inf = iMask | ((levabsesc << 1) - iMask) | sign;

    /* Assert to make sure that the code fits in the VLC */
    /* make sure that we are in High Profile to represent level_prefix > 15 */
    if (numPrefix > 0 &&  !IS_FREXT_PROFILE( profile_idc ))
    {
      //error( "level_prefix must be <= 15 except in High Profile\n",  1000 );
      se->len = 0x0000FFFF; // This can be some other big number
      return (se->len);
    }
    se->len = 28 + (numPrefix << 1);
  }

  symbol2vlc(se);

  writeUVLC2buffer(se, dp->bitstream);

  if(se->type != SE_HEADER)
    dp->bitstream->write_flag = 1;

#if TRACE
  if(dp->bitstream->trace_enabled)
    trace2out (se);
#endif

  return (se->len);
}


#if TRACE
int bitcounter = 0;

/*!
 ************************************************************************
 * \brief
 *    Write out a trace string on the trace file
 ************************************************************************
 */
void trace2out(SyntaxElement *sym)
{
  static
  int i, chars;

  if (p_trace != NULL)
  {
    putc('@', p_trace);
    chars = fprintf(p_trace, "%i", bitcounter);
    while(chars++ < 6)
      putc(' ',p_trace);

    chars += fprintf(p_trace, "%s", sym->tracestring);
    while(chars++ < 55)
      putc(' ',p_trace);

    // align bit pattern
    if(sym->len<15)
    {
      for(i=0 ; i<15-sym->len ; i++)
        fputc(' ', p_trace);
    }

    // print bit pattern
    bitcounter += sym->len;
    for(i=1 ; i<=sym->len ; i++)
    {
      if((sym->bitpattern >> (sym->len-i)) & 0x1)
        fputc('1', p_trace);
      else
        fputc('0', p_trace);
    }
    fprintf(p_trace, " (%3d) \n",sym->value1);
  }
  fflush (p_trace);
}

void trace2out_cabac(SyntaxElement *sym)
{
  int chars;

  if (p_trace != NULL)
  {
    putc('@', p_trace);
    chars = fprintf(p_trace, "%i", bitcounter);
    while(chars++ < 6)
      putc(' ',p_trace);

    chars += fprintf(p_trace, "%s", sym->tracestring);
    while(chars++ < 70)
      putc(' ',p_trace);

    fprintf(p_trace, " (%3d) \n",sym->value1);
  }
  fflush (p_trace);
  bitcounter += sym->len;
}
#endif


/*!
 ************************************************************************
 * \brief
 *    puts the less than 8 bits in the byte buffer of the Bitstream into
 *    the streamBuffer.
 *
 * \param
 *   currStream: the Bitstream the alignment should be established
 *
 ************************************************************************
 */
void writeVlcByteAlign(Bitstream* currStream, StatParameters *cur_stats)
{
  if (currStream->bits_to_go < 8)
  { // trailing bits to process
    currStream->byte_buf = (currStream->byte_buf << currStream->bits_to_go) | (0xff >> (8 - currStream->bits_to_go));
    currStream->streamBuffer[currStream->byte_pos++] = currStream->byte_buf;
    cur_stats->bit_use_stuffingBits[img->type] += currStream->bits_to_go;    
    currStream->bits_to_go = 8;
  }
}