vlc.c

压缩JM12.3d的完整的全部C语言的代码文档,用于嵌入式系统的压缩编解码

/*!
 ***************************************************************************
 * \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

//! gives codeword number from CBP value, both for intra and inter
static const unsigned char NCBP[2][48][2]=
{
  {  // 0      1        2       3       4       5       6       7       8       9      10      11
    { 1, 0},{10, 1},{11, 2},{ 6, 5},{12, 3},{ 7, 6},{14,14},{ 2,10},{13, 4},{15,15},{ 8, 7},{ 3,11},
    { 9, 8},{ 4,12},{ 5,13},{ 0, 9},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},
    { 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},
    { 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0},{ 0, 0}
  },
  {
    { 3, 0},{29, 2},{30, 3},{17, 7},{31, 4},{18, 8},{37,17},{ 8,13},{32, 5},{38,18},{19, 9},{ 9,14},
    {20,10},{10,15},{11,16},{ 2,11},{16, 1},{33,32},{34,33},{21,36},{35,34},{22,37},{39,44},{ 4,40},
    {36,35},{40,45},{23,38},{ 5,41},{24,39},{ 6,42},{ 7,43},{ 1,19},{41, 6},{42,24},{43,25},{25,20},
    {44,26},{26,21},{46,46},{12,28},{45,27},{47,47},{27,22},{13,29},{28,23},{14,30},{15,31},{ 0,12}
  }
};


/*!
 *************************************************************************************
 * \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.
 *
 *************************************************************************************
 */
Boolean 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 ((Boolean) 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)>>1;

  for (i=0; i < 33 && nn != 0; i++)
  {
    nn >>= 1;
  }
  *len  = (i << 1) + 1;
  *info = ue + 1 - (1 << 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 sign = (se <= 0) ? 1 : 0;
  int n = iabs(se) << 1;   //  n+1 is the number in the code table.  Based on this we find length and info
  int nn = (n >> 1);
  int i;
  for (i=0; i < 33 && nn != 0; i++)
  {
    nn >>= 1;
  }
  *len  = (i << 1) + 1;
  *info = n - (1 << 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)
{
  ue_linfo(NCBP[img->ChromaArrayType ? 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)
{
  ue_linfo(NCBP[img->ChromaArrayType ? 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)
{
  static const int NTAB[2][2]=
  {
    {1,5},
    {3,0}
  };
  static const int LEVRUN[4]=
  {
    2,1,0,0
  };

  int levabs,i,n,sign = 0,nn;

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

  if (level <= 0)
  {
    sign=1;
  }

  levabs = iabs(level);

  if (levabs <= LEVRUN[run])
  {
    n = NTAB[levabs - 1][run] + 1;
  }
  else
  {
    n = (levabs - LEVRUN[run]) * 8 + run * 2;
  }

  nn = n >> 1;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn >>= 1;
  }
  *len  = (i << 1) + 1;
  *info = n - (1 << 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)
{
  static const byte LEVRUN[16]=
  {
    4,2,2,1,1,1,1,1,1,1,0,0,0,0,0,0
  };
  static 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;
  }

  sign   = (level <= 0) ? 1 : 0;
  levabs = iabs(level);

  n = (levabs <= LEVRUN[run]) ? NTAB[levabs - 1][run] + 1 : (levabs - LEVRUN[run]) * 32 + run * 2;

  nn = n >> 1;

  for (i=0; i < 16 && nn != 0; i++)
  {
    nn >>= 1;
  }
  *len  = (i << 1) + 1;
  *info = n - (1 << 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 >> 1;
  assert (suffix_len<32);
  sym->bitpattern = (1<<suffix_len)|(sym->inf & ((1<<suffix_len) - 1));
  return 0;
}

/*!
************************************************************************
* \brief
*    generates UVLC code and passes the codeword to the buffer
************************************************************************
*/
void writeSE_UVLC(SyntaxElement *se, DataPartition *dp)
{
  ue_linfo (se->value1,se->value2,&(se->len),&(se->inf));
  symbol2uvlc(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
}

/*!
************************************************************************
* \brief
*    generates UVLC code and passes the codeword to the buffer