vlc.c

H264视频编解码程序

/*!
 ***************************************************************************
 * \file vlc.c
 *
 * \brief
 *    (CA)VLC coding functions
 *
 * \author
 *    Main contributors (see contributors.h for copyright, address and affiliation details)
 *    - Inge Lille-Langoy               <[e-mail]>
 *    - Detlev Marpe                    <[e-mail]>
 *    - Stephan Wenger                  <[e-mail]>
 ***************************************************************************
 */

#include "contributors.h"

#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <assert.h>

#include "global.h"

#include "vlc.h"

#if TRACE
#define SYMTRACESTRING(s) strncpy(sym.tracestring,s,TRACESTRING_SIZE)
#else
#define SYMTRACESTRING(s) // do nothing
#endif


/*! 
 *************************************************************************************
 * \brief
 *    ue_v, writes an ue(v) syntax element, returns the length in bits
 *
 * \param tracestring
 *    the string for the trace file
 * \param value
 *    the value to be coded
 *  \param bitstream
 *    the target bitstream the value should be coded into
 *
 * \return
 *    Number of bits used by the coded syntax element
 *
 * \ note
 *    This function writes always the bit buffer for the progressive scan flag, and
 *    should not be used (or should be modified appropriately) for the interlace crap
 *    When used in the context of the Parameter Sets, this is obviously not a
 *    problem.
 *
 *************************************************************************************
 */
int ue_v (char *tracestring, int value, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;
  sym->value1 = value;
  sym->value2 = 0;

  assert (bitstream->streamBuffer != NULL);

  ue_linfo(sym->value1,sym->value2,&(sym->len),&(sym->inf));
  symbol2uvlc(sym);

  writeUVLC2buffer (sym, bitstream);

#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
  trace2out (sym);
#endif

  return (sym->len);
}


/*! 
 *************************************************************************************
 * \brief
 *    se_v, writes an se(v) syntax element, returns the length in bits
 *
 * \param tracestring
 *    the string for the trace file
 * \param value
 *    the value to be coded
 *  \param bitstream
 *    the target bitstream the value should be coded into
 *
 * \return
 *    Number of bits used by the coded syntax element
 *
 * \ note
 *    This function writes always the bit buffer for the progressive scan flag, and
 *    should not be used (or should be modified appropriately) for the interlace crap
 *    When used in the context of the Parameter Sets, this is obviously not a
 *    problem.
 *
 *************************************************************************************
 */
int se_v (char *tracestring, int value, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;
  sym->value1 = value;
  sym->value2 = 0;

  assert (bitstream->streamBuffer != NULL);
  
  se_linfo(sym->value1,sym->value2,&(sym->len),&(sym->inf));
  symbol2uvlc(sym);

  writeUVLC2buffer (sym, bitstream);

#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
  trace2out (sym);
#endif

  return (sym->len);
}


/*! 
 *************************************************************************************
 * \brief
 *    u_1, writes a flag (u(1) syntax element, returns the length in bits, 
 *    always 1
 *
 * \param tracestring
 *    the string for the trace file
 * \param value
 *    the value to be coded
 *  \param bitstream
 *    the target bitstream the value should be coded into
 *
 * \return
 *    Number of bits used by the coded syntax element (always 1)
 *
 * \ note
 *    This function writes always the bit buffer for the progressive scan flag, and
 *    should not be used (or should be modified appropriately) for the interlace crap
 *    When used in the context of the Parameter Sets, this is obviously not a
 *    problem.
 *
 *************************************************************************************
 */
int u_1 (char *tracestring, int value, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;

  sym->bitpattern = value;
  sym->len = 1;
  sym->value1 = value;

  assert (bitstream->streamBuffer != NULL);

  writeUVLC2buffer(sym, bitstream);
  
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
  trace2out (sym);
#endif

  return (sym->len);
}


/*! 
 *************************************************************************************
 * \brief
 *    u_v, writes a n bit fixed length syntax element, returns the length in bits, 
 *
 * \param n
 *    length in bits
 * \param tracestring
 *    the string for the trace file
 * \param value
 *    the value to be coded
 *  \param bitstream
 *    the target bitstream the value should be coded into
 *
 * \return
 *    Number of bits used by the coded syntax element 
 *
 * \ note
 *    This function writes always the bit buffer for the progressive scan flag, and
 *    should not be used (or should be modified appropriately) for the interlace crap
 *    When used in the context of the Parameter Sets, this is obviously not a
 *    problem.
 *
 *************************************************************************************
 */

int u_v (int n, char *tracestring, int value, Bitstream *bitstream)
{
  SyntaxElement symbol, *sym=&symbol;

  sym->bitpattern = value;
  sym->len = n;
  sym->value1 = value;

  assert (bitstream->streamBuffer != NULL);

  writeUVLC2buffer(sym, bitstream);
  
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
  trace2out (sym);
#endif

  return (sym->len);
}


/*!
 ************************************************************************
 * \brief
 *    mapping for ue(v) syntax elements
 * \param ue
 *    value to be mapped
 * \param dummy
 *    dummy parameter
 * \param info
 *    returns mapped value
 * \param len
 *    returns mapped value length
 ************************************************************************
 */
void ue_linfo(int ue, int dummy, int *len,int *info)
{
  int i,nn;

  nn=(ue+1)/2;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn /= 2;
  }
  *len= 2*i + 1;
  *info=ue+1-(int)pow(2,i);
}


/*!
 ************************************************************************
 * \brief
 *    mapping for se(v) syntax elements
 * \param se
 *    value to be mapped
 * \param dummy
 *    dummy parameter
 * \param len
 *    returns mapped value length
 * \param info
 *    returns mapped value
 ************************************************************************
 */
void se_linfo(int se, int dummy, int *len,int *info)
{

  int i,n,sign,nn;

  sign=0;

  if (se <= 0)
  {
    sign=1;
  }
  n=absm(se) << 1;

  /*
  n+1 is the number in the code table.  Based on this we find length and info
  */

  nn=n/2;
  for (i=0; i < 16 && nn != 0; i++)
  {
    nn /= 2;
  }
  *len=i*2 + 1;
  *info=n - (int)pow(2,i) + sign;
}


/*!
 ************************************************************************
 * \par Input:
 *    Number in the code table
 * \par Output:
 *    length and info
 ************************************************************************
 */
void cbp_linfo_intra(int cbp, int dummy, int *len,int *info)
{
  extern const unsigned char NCBP[2][48][2];
  ue_linfo(NCBP[img->yuv_format?1:0][cbp][0], dummy, len, info);
}


/*!
 ************************************************************************
 * \par Input:
 *    Number in the code table
 * \par Output:
 *    length and info
 ************************************************************************
 */
void cbp_linfo_inter(int cbp, int dummy, int *len,int *info)
{
  extern const unsigned char NCBP[2][48][2];
  ue_linfo(NCBP[img->yuv_format?1:0][cbp][1], dummy, len, info);
}


/*!
 ************************************************************************
 * \brief
 *    2x2 transform of chroma DC
 * \par Input:
 *    level and run for coefficients
 * \par Output:
 *    length and info
 * \note
 *    see ITU document for bit assignment
 ************************************************************************
 */
void levrun_linfo_c2x2(int level,int run,int *len,int *info)
{
  const int NTAB[2][2]=
  {
    {1,5},
    {3,0}
  };
  const int LEVRUN[4]=
  {
    2,1,0,0
  };

  int levabs,i,n,sign,nn;

  if (level == 0) //  check if the coefficient sign EOB (level=0)
  {
    *len=1;
    return;
  }
  sign=0;
  if (level <= 0)
  {
    sign=1;
  }
  levabs=absm(level);
  if (levabs <= LEVRUN[run])
  {
    n=NTAB[levabs-1][run]+1;
  }
  else
  {
    n=(levabs-LEVRUN[run])*8 + run*2;
  }

  nn=n/2;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn /= 2;
  }
  *len= 2*i + 1;
  *info=n-(int)pow(2,i)+sign;
}


/*!
 ************************************************************************
 * \brief
 *    Single scan coefficients
 * \par Input:
 *    level and run for coefficients
 * \par Output:
 *    length and info
 * \note
 *    see ITU document for bit assignment
 ************************************************************************
 */
void levrun_linfo_inter(int level,int run,int *len,int *info)
{
  const byte LEVRUN[16]=
  {
    4,2,2,1,1,1,1,1,1,1,0,0,0,0,0,0
  };
  const byte NTAB[4][10]=
  {
    { 1, 3, 5, 9,11,13,21,23,25,27},
    { 7,17,19, 0, 0, 0, 0, 0, 0, 0},
    {15, 0, 0, 0, 0, 0, 0, 0, 0, 0},
    {29, 0, 0, 0, 0, 0, 0, 0, 0, 0},
  };

  int levabs,i,n,sign,nn;

  if (level == 0)           //  check for EOB
  {
    *len=1;
    return;
  }

  if (level <= 0)
    sign=1;
  else
    sign=0;

  levabs=absm(level);
  if (levabs <= LEVRUN[run])
  {
    n=NTAB[levabs-1][run]+1;
  }
  else
  {
    n=(levabs-LEVRUN[run])*32 + run*2;
  }

  nn=n/2;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn /= 2;
  }
  *len= 2*i + 1;
  *info=n-(int)pow(2,i)+sign;

}


/*!
 ************************************************************************
 * \brief
 *    Double scan coefficients
 * \par Input:
 *    level and run for coefficients
 * \par Output:
 *    length and info
 * \note
 *    see ITU document for bit assignment
 ************************************************************************
 */
void levrun_linfo_intra(int level,int run,int *len,int *info)
{
  const byte LEVRUN[8]=
  {
    9,3,1,1,1,0,0,0
  };

  const byte NTAB[9][5] =
  {
    { 1, 3, 7,15,17},
    { 5,19, 0, 0, 0},
    { 9,21, 0, 0, 0},
    {11, 0, 0, 0, 0},
    {13, 0, 0, 0, 0},
    {23, 0, 0, 0, 0},
    {25, 0, 0, 0, 0},
    {27, 0, 0, 0, 0},
    {29, 0, 0, 0, 0},
  };

  int levabs,i,n,sign,nn;

  if (level == 0)     //  check for EOB
  {
    *len=1;
    return;
  }
  if (level <= 0)
    sign=1;
  else
    sign=0;

  levabs=absm(level);
  if (levabs <= LEVRUN[run])
  {
    n=NTAB[levabs-1][run]+1;
  }
  else
  {
    n=(levabs-LEVRUN[run])*16 + 16 + run*2;
  }

  nn=n/2;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn /= 2;
  }
  *len= 2*i + 1;
  *info=n-(int)pow(2,i)+sign;
}


/*!
 ************************************************************************
 * \brief
 *    Makes code word and passes it back
 *    A code word has the following format: 0 0 0 ... 1 Xn ...X2 X1 X0.
 *
 * \par Input:
 *    Info   : Xn..X2 X1 X0                                             \n
 *    Length : Total number of bits in the codeword
 ************************************************************************
 */
 // NOTE this function is called with sym->inf > (1<<(sym->len/2)).  The upper bits of inf are junk
int symbol2uvlc(SyntaxElement *sym)
{
  int suffix_len=sym->len/2;  
  sym->bitpattern = (1<<suffix_len)|(sym->inf&((1<<suffix_len)-1));
  return 0;
}


/*!
 ************************************************************************
 * \brief
 *    generates UVLC code and passes the codeword to the buffer
 ************************************************************************
 */
int writeSyntaxElement_UVLC(SyntaxElement *se, DataPartition *this_dataPart)
{
  se->mapping(se->value1,se->value2,&(se->len),&(se->inf));
  symbol2uvlc(se);

  writeUVLC2buffer(se, this_dataPart->bitstream);

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

#if TRACE
  if(se->type <= 1)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    generates code and passes the codeword to the buffer
 ************************************************************************
 */
int writeSyntaxElement_Intra4x4PredictionMode(SyntaxElement *se, DataPartition *this_dataPart)
{

  if (se->value1 == -1)
  {
    se->len = 1;
    se->inf = 1;
  }
  else 
  {
    se->len = 4;  
    se->inf = se->value1;
  }

  se->bitpattern = se->inf;
  writeUVLC2buffer(se, this_dataPart->bitstream);

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

#if TRACE
  if(se->type <= 1)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    generates UVLC code and passes the codeword to the buffer
 * \author
 *  Tian Dong
 ************************************************************************
 */
int writeSyntaxElement2Buf_UVLC(SyntaxElement *se, Bitstream* this_streamBuffer )
{

  se->mapping(se->value1,se->value2,&(se->len),&(se->inf));

  symbol2uvlc(se);

  writeUVLC2buffer(se, this_streamBuffer );

#if TRACE
  if(se->type <= 1)
    trace2out (se);
#endif

  return (se->len);
}


/*!
 ************************************************************************
 * \brief
 *    writes UVLC code to the appropriate buffer
 ************************************************************************
 */
void  writeUVLC2buffer(SyntaxElement *se, Bitstream *currStream)
{

  int i;
  unsigned int mask = 1 << (se->len-1);

  // Add the new bits to the bitstream.
  // Write out a byte if it is full
  for (i=0; i<se->len; i++)
  {
    currStream->byte_buf <<= 1;
    if (se->bitpattern & mask)
      currStream->byte_buf |= 1;
    currStream->bits_to_go--;
    mask >>= 1;
    if (currStream->bits_to_go==0)
    {
      currStream->bits_to_go = 8;
      currStream->streamBuffer[currStream->byte_pos++]=currStream->byte_buf;
      currStream->byte_buf = 0;
    }
  }