vlc.c

包含FRExt部分的JM源码

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

#include "contributors.h"

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

#include "elements.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 part
 *    the Data Partition 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, DataPartition *part)
{
  SyntaxElement symbol, *sym=&symbol;
  sym->type = SE_HEADER;
  sym->mapping = ue_linfo;               // Mapping rule: unsigned integer
  sym->value1 = value;
  sym->value2 = 0;
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
#endif
  assert (part->bitstream->streamBuffer != NULL);
  return writeSyntaxElement_UVLC (sym, part);
}


/*! 
 *************************************************************************************
 * \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 part
 *    the Data Partition 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, DataPartition *part)
{
  SyntaxElement symbol, *sym=&symbol;
  sym->type = SE_HEADER;
  sym->mapping = se_linfo;               // Mapping rule: signed integer
  sym->value1 = value;
  sym->value2 = 0;
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
#endif
  assert (part->bitstream->streamBuffer != NULL);
  return writeSyntaxElement_UVLC (sym, part);
}


/*! 
 *************************************************************************************
 * \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 part
 *    the Data Partition 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, DataPartition *part)
{
  SyntaxElement symbol, *sym=&symbol;

  sym->bitpattern = value;
  sym->len = 1;
  sym->type = SE_HEADER;
  sym->value1 = value;
  sym->value2 = 0;
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
#endif
  assert (part->bitstream->streamBuffer != NULL);
  return writeSyntaxElement_fixed(sym, part);
}


/*! 
 *************************************************************************************
 * \brief
 *    u_v, writes a 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 part
 *    the Data Partition 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, DataPartition *part)
{
  SyntaxElement symbol, *sym=&symbol;

  sym->bitpattern = value;
  sym->len = n;
  sym->type = SE_HEADER;
  sym->value1 = value;
  sym->value2 = 0;
#if TRACE
  strncpy(sym->tracestring,tracestring,TRACESTRING_SIZE);
#endif
  assert (part->bitstream->streamBuffer != NULL);
  return writeSyntaxElement_fixed(sym, part);
}


/*!
 ************************************************************************
 * \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=abs(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 int NCBP[48][2];
  ue_linfo(NCBP[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 int NCBP[48][2];
  ue_linfo(NCBP[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=abs(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 coefficiets
 * \par Output:
 *    lenght 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=abs(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 coefficiets
 * \par Output:
 *    lenght and info
 * \note
 *    see ITU document for bit assignment
 ************************************************************************