liveMedia/MP3InternalsHuffman.cpp File Reference

#include "MP3InternalsHuffman.hh"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

Include dependency graph for MP3InternalsHuffman.cpp:

Go to the source code of this file.

Data Structures
struct	huffcodetab
Defines
#define	TRUNC_FAVORa
#define	HUFFBITS   unsigned long int
#define	SIZEOF_HUFFBITS   4
#define	HTN   34
#define	MXOFF   250
Functions
void	updateSideInfoForHuffman (MP3SideInfo &sideInfo, Boolean isMPEG2, unsigned char const *mainDataPtr, unsigned p23L0, unsigned p23L1, unsigned &part23Length0a, unsigned &part23Length0aTruncation, unsigned &part23Length0b, unsigned &part23Length0bTruncation, unsigned &part23Length1a, unsigned &part23Length1aTruncation, unsigned &part23Length1b, unsigned &part23Length1bTruncation)
static void	rsf_getline (char *line, unsigned max, unsigned char **fi)
static void	rsfscanf (unsigned char **fi, unsigned int *v)
static int	read_decoder_table (unsigned char *fi)
static void	initialize_huffman ()
static unsigned	rsf_get_scale_factors_1 (MP3SideInfo::gr_info_s_t *gr_info)
static unsigned	rsf_get_scale_factors_2 (MP3SideInfo::gr_info_s_t *gr_info)
static unsigned	getScaleFactorsLength (MP3SideInfo::gr_info_s_t *gr, Boolean isMPEG2)
static int	rsf_huffman_decoder (BitVector &bv, struct huffcodetab const *h, int *x, int *y, int *v, int *w)
void	MP3HuffmanDecode (MP3SideInfo::gr_info_s_t *gr, Boolean isMPEG2, unsigned char const *fromBasePtr, unsigned fromBitOffset, unsigned fromLength, unsigned &scaleFactorsLength, MP3HuffmanEncodingInfo &hei)
Variables
static unsigned	debugCount = 0
static struct huffcodetab	rsf_ht [HTN]
static unsigned char const	slen [2][16]
static unsigned char const	stab [3][6][4]
unsigned	n_slen2 []
unsigned	i_slen2 []
HUFFBITS	dmask = 1 << (SIZEOF_HUFFBITS*8-1)
unsigned int	hs = SIZEOF_HUFFBITS*8

---

Define Documentation

#define HTN   34

Definition at line 319 of file MP3InternalsHuffman.cpp.

Referenced by initialize_huffman(), and read_decoder_table().

#define HUFFBITS   unsigned long int

Definition at line 317 of file MP3InternalsHuffman.cpp.

Referenced by rsf_huffman_decoder().

#define MXOFF   250

Definition at line 320 of file MP3InternalsHuffman.cpp.

Referenced by rsf_huffman_decoder().

#define SIZEOF_HUFFBITS   4

Definition at line 318 of file MP3InternalsHuffman.cpp.

#define TRUNC_FAVORa

Definition at line 43 of file MP3InternalsHuffman.cpp.

---

Function Documentation

static unsigned getScaleFactorsLength	(	MP3SideInfo::gr_info_s_t *	gr,
		Boolean	isMPEG2
	)			[static]

Definition at line 531 of file MP3InternalsHuffman.cpp.

References rsf_get_scale_factors_1(), and rsf_get_scale_factors_2().

Referenced by MP3HuffmanDecode().

                                                       {
  return isMPEG2 ? rsf_get_scale_factors_2(gr)
                 : rsf_get_scale_factors_1(gr);
}

static void initialize_huffman

(

)

[static]

Definition at line 420 of file MP3InternalsHuffman.cpp.

References False, HTN, huffdec, read_decoder_table(), and True.

Referenced by MP3HuffmanDecode().

                                 {
  static Boolean huffman_initialized = False;

   if (huffman_initialized) return;

   if (read_decoder_table(huffdec) != HTN) {
#ifdef DEBUG
      fprintf(stderr,"decoder table read error\n");
#endif
      return;
      }
   huffman_initialized = True;
}

void MP3HuffmanDecode	(	MP3SideInfo::gr_info_s_t *	gr,
		Boolean	isMPEG2,
		unsigned char const *	fromBasePtr,
		unsigned	fromBitOffset,
		unsigned	fromLength,
		unsigned &	scaleFactorsLength,
		MP3HuffmanEncodingInfo &	hei
	)

Definition at line 541 of file MP3InternalsHuffman.cpp.

References MP3HuffmanEncodingInfo::allBitOffsets, MP3SideInfo::gr_info_s::big_values, BitVector::curBitIndex(), MP3HuffmanEncodingInfo::decodedValues, getScaleFactorsLength(), if(), initialize_huffman(), NULL, MP3HuffmanEncodingInfo::numSamples, MP3HuffmanEncodingInfo::reg1Start, MP3HuffmanEncodingInfo::reg2Start, MP3SideInfo::gr_info_s::region1start, MP3SideInfo::gr_info_s::region2start, rsf_ht, rsf_huffman_decoder(), BitVector::skipBits(), and MP3SideInfo::gr_info_s::table_select.

Referenced by updateSideInfoForHuffman().

                                                   {
   unsigned i;
   int x, y, v, w;
   struct huffcodetab *h;
   BitVector bv((unsigned char*)fromBasePtr, fromBitOffset, fromLength);

   /* Compute the size of the scale factors (& also advance bv): */
   scaleFactorsLength = getScaleFactorsLength(gr, isMPEG2);
   bv.skipBits(scaleFactorsLength);

   initialize_huffman();

   hei.reg1Start = hei.reg2Start = hei.numSamples = 0;

   /* Read bigvalues area. */
   if (gr->big_values < gr->region1start + gr->region2start) {
     gr->big_values = gr->region1start + gr->region2start; /* sanity check */
   }
   for (i = 0; i < gr->big_values; ++i) {
     if (i < gr->region1start) {
       /* in region 0 */
       h = &rsf_ht[gr->table_select[0]];
     } else if (i < gr->region2start) {
       /* in region 1 */
       h = &rsf_ht[gr->table_select[1]];
       if (hei.reg1Start == 0) {
         hei.reg1Start = bv.curBitIndex();
       }
     } else {
       /* in region 2 */
       h = &rsf_ht[gr->table_select[2]];
       if (hei.reg2Start == 0) {
         hei.reg2Start = bv.curBitIndex();
       }
     }

     hei.allBitOffsets[i] = bv.curBitIndex();
     rsf_huffman_decoder(bv, h, &x, &y, &v, &w);
     if (hei.decodedValues != NULL) {
       // Record the decoded values:
       unsigned* ptr = &hei.decodedValues[4*i];
       ptr[0] = x; ptr[1] = y; ptr[2] = v; ptr[3] = w;
     }
   }
   hei.bigvalStart = bv.curBitIndex();

   /* Read count1 area. */
   h = &rsf_ht[gr->count1table_select+32];
   while (bv.curBitIndex() < bv.totNumBits() &&  i < SSLIMIT*SBLIMIT) {
     hei.allBitOffsets[i] = bv.curBitIndex();
     rsf_huffman_decoder(bv, h, &x, &y, &v, &w);
     if (hei.decodedValues != NULL) {
       // Record the decoded values:
       unsigned* ptr = &hei.decodedValues[4*i];
       ptr[0] = x; ptr[1] = y; ptr[2] = v; ptr[3] = w;
     }
     ++i;
   }

   hei.allBitOffsets[i] = bv.curBitIndex();
   hei.numSamples = i;
}

static int read_decoder_table

(

unsigned char *

fi

)

[static]

Definition at line 340 of file MP3InternalsHuffman.cpp.

References huffcodetab::hlen, HTN, huffcodetab::linbits, huffcodetab::linmax, NULL, huffcodetab::ref, rsf_getline(), rsf_ht, rsfscanf(), huffcodetab::table, huffcodetab::tablename, huffcodetab::treelen, huffcodetab::val, huffcodetab::xlen, and huffcodetab::ylen.

Referenced by initialize_huffman().

                                                 {
  int n,i,nn,t;
  unsigned int v0,v1;
  char command[100],line[100];
  for (n=0;n<HTN;n++) {
    rsf_ht[n].table = NULL;
    rsf_ht[n].hlen = NULL;

    /* .table number treelen xlen ylen linbits */
    do {
      rsf_getline(line,99,&fi);
    } while ((line[0] == '#') || (line[0] < ' '));

    sscanf(line,"%s %s %u %u %u %u",command,rsf_ht[n].tablename,
           &rsf_ht[n].treelen, &rsf_ht[n].xlen, &rsf_ht[n].ylen, &rsf_ht[n].linbits);
    if (strcmp(command,".end")==0)
      return n;
    else if (strcmp(command,".table")!=0) {
#ifdef DEBUG
      fprintf(stderr,"huffman table %u data corrupted\n",n);
#endif
      return -1;
    }
    rsf_ht[n].linmax = (1<<rsf_ht[n].linbits)-1;

    sscanf(rsf_ht[n].tablename,"%u",&nn);
    if (nn != n) {
#ifdef DEBUG
      fprintf(stderr,"wrong table number %u\n",n);
#endif
      return(-2);
    }
    do {
      rsf_getline(line,99,&fi);
    } while ((line[0] == '#') || (line[0] < ' '));

    sscanf(line,"%s %u",command,&t);
    if (strcmp(command,".reference")==0) {
      rsf_ht[n].ref   = t;
      rsf_ht[n].val   = rsf_ht[t].val;
      rsf_ht[n].treelen  = rsf_ht[t].treelen;
      if ( (rsf_ht[n].xlen != rsf_ht[t].xlen) ||
           (rsf_ht[n].ylen != rsf_ht[t].ylen)  ) {
#ifdef DEBUG
        fprintf(stderr,"wrong table %u reference\n",n);
#endif
        return (-3);
      };
      while ((line[0] == '#') || (line[0] < ' ') ) {
        rsf_getline(line,99,&fi);
      }
    }
    else if (strcmp(command,".treedata")==0) {
      rsf_ht[n].ref  = -1;
      rsf_ht[n].val = (unsigned char (*)[2])
        new unsigned char[2*(rsf_ht[n].treelen)];
      if ((rsf_ht[n].val == NULL) && ( rsf_ht[n].treelen != 0 )){
#ifdef DEBUG
        fprintf(stderr, "heaperror at table %d\n",n);
#endif
        return -1;
      }
      for (i=0;(unsigned)i<rsf_ht[n].treelen; i++) {
        rsfscanf(&fi, &v0);
        rsfscanf(&fi, &v1);
/*replaces        fscanf(fi,"%x %x",&v0, &v1);*/
        rsf_ht[n].val[i][0]=(unsigned char)v0;
        rsf_ht[n].val[i][1]=(unsigned char)v1;
      }
      rsf_getline(line,99,&fi); /* read the rest of the line */
    }
    else {
#ifdef DEBUG
      fprintf(stderr,"huffman decodertable error at table %d\n",n);
#endif
    }
  }
  return n;
}

static unsigned rsf_get_scale_factors_1

(

MP3SideInfo::gr_info_s_t *

gr_info

)

[static]

Definition at line 448 of file MP3InternalsHuffman.cpp.

References MP3SideInfo::gr_info_s::block_type, MP3SideInfo::gr_info_s::mixed_block_flag, MP3SideInfo::gr_info_s::scalefac_compress, MP3SideInfo::gr_info_s::scfsi, and slen.

Referenced by getScaleFactorsLength().

                                                                         {
   int numbits;
   int num0 = slen[0][gr_info->scalefac_compress];
   int num1 = slen[1][gr_info->scalefac_compress];

    if (gr_info->block_type == 2)
    {
      numbits = (num0 + num1) * 18;

      if (gr_info->mixed_block_flag) {
         numbits -= num0; /* num0 * 17 + num1 * 18 */
      }
    }
    else
    {
      int scfsi = gr_info->scfsi;

      if(scfsi < 0) { /* scfsi < 0 => granule == 0 */
         numbits = (num0 + num1) * 10 + num0;
      }
      else {
        numbits = 0;
        if(!(scfsi & 0x8)) {
          numbits += num0 * 6;
        }
        else {
        }

        if(!(scfsi & 0x4)) {
          numbits += num0 * 5;
        }
        else {
        }

        if(!(scfsi & 0x2)) {
          numbits += num1 * 5;
        }
        else {
        }

        if(!(scfsi & 0x1)) {
          numbits += num1 * 5;
        }
        else {
        }
      }
    }

    return numbits;
}

static unsigned rsf_get_scale_factors_2

(

MP3SideInfo::gr_info_s_t *

gr_info

)

[static]

Definition at line 502 of file MP3InternalsHuffman.cpp.

References MP3SideInfo::gr_info_s::block_type, MP3SideInfo::gr_info_s::mixed_block_flag, n_slen2, MP3SideInfo::gr_info_s::preflag, MP3SideInfo::gr_info_s::scalefac_compress, slen, and stab.

Referenced by getScaleFactorsLength().

                                                                         {
  unsigned char const* pnt;
  int i;
  unsigned int slen;
  int n = 0;
  int numbits = 0;

  slen = n_slen2[gr_info->scalefac_compress];

  gr_info->preflag = (slen>>15) & 0x1;

  n = 0;
  if( gr_info->block_type == 2 ) {
    n++;
    if(gr_info->mixed_block_flag)
      n++;
  }

  pnt = stab[n][(slen>>12)&0x7];

  for(i=0;i<4;i++) {
    int num = slen & 0x7;
    slen >>= 3;
    numbits += pnt[i] * num;
  }

  return numbits;
}

static void rsf_getline	(	char *	line,
		unsigned	max,
		unsigned char **	fi
	)			[static]

Definition at line 292 of file MP3InternalsHuffman.cpp.

Referenced by read_decoder_table().

                                                                     {
  unsigned i;
  for (i = 0; i < max; ++i) {
    line[i] = *(*fi)++;
    if (line[i] == '\n') {
      line[i++] = '\0';
      return;
    }
  }
  line[i] = '\0';
}

static int rsf_huffman_decoder	(	BitVector &	bv,
		struct huffcodetab const *	h,
		int *	x,
		int *	y,
		int *	v,
		int *	w
	)			[static]

Definition at line 612 of file MP3InternalsHuffman.cpp.

References BitVector::get1Bit(), BitVector::getBits(), HUFFBITS, huffcodetab::linbits, MXOFF, NULL, huffcodetab::tablename, huffcodetab::treelen, huffcodetab::val, huffcodetab::xlen, and huffcodetab::ylen.

Referenced by MP3HuffmanDecode().

                                               {
  HUFFBITS level;
  unsigned point = 0;
  int error = 1;
  level     = dmask;
  *x = *y = *v = *w = 0;
  if (h->val == NULL) return 2;

  /* table 0 needs no bits */
  if (h->treelen == 0) return 0;

  /* Lookup in Huffman table. */

  do {
    if (h->val[point][0]==0) {   /*end of tree*/
      *x = h->val[point][1] >> 4;
      *y = h->val[point][1] & 0xf;

      error = 0;
      break;
    }
    if (bv.get1Bit()) {
      while (h->val[point][1] >= MXOFF) point += h->val[point][1];
      point += h->val[point][1];
    }
    else {
      while (h->val[point][0] >= MXOFF) point += h->val[point][0];
      point += h->val[point][0];
    }
    level >>= 1;
  } while (level  || (point < h->treelen) );

  /* Check for error. */

  if (error) { /* set x and y to a medium value as a simple concealment */
    printf("Illegal Huffman code in data.\n");
    *x = ((h->xlen-1) << 1);
    *y = ((h->ylen-1) << 1);
  }

  /* Process sign encodings for quadruples tables. */

  if (h->tablename[0] == '3'
      && (h->tablename[1] == '2' || h->tablename[1] == '3')) {
     *v = (*y>>3) & 1;
     *w = (*y>>2) & 1;
     *x = (*y>>1) & 1;
     *y = *y & 1;

     if (*v)
        if (bv.get1Bit() == 1) *v = -*v;
     if (*w)
        if (bv.get1Bit() == 1) *w = -*w;
     if (*x)
        if (bv.get1Bit() == 1) *x = -*x;
     if (*y)
        if (bv.get1Bit() == 1) *y = -*y;
     }

  /* Process sign and escape encodings for dual tables. */

  else {
     if (h->linbits)
       if ((h->xlen-1) == (unsigned)*x)
         *x += bv.getBits(h->linbits);
     if (*x)
        if (bv.get1Bit() == 1) *x = -*x;
     if (h->linbits)
       if ((h->ylen-1) == (unsigned)*y)
         *y += bv.getBits(h->linbits);
     if (*y)
        if (bv.get1Bit() == 1) *y = -*y;
  }

  return error;
}

static void rsfscanf	(	unsigned char **	fi,
		unsigned int *	v
	)			[static]

Definition at line 304 of file MP3InternalsHuffman.cpp.

Referenced by read_decoder_table().

                                                          {
  while (sscanf((char*)*fi, "%x", v) == 0) {
    /* skip past the next '\0' */
    while (*(*fi)++ != '\0') {}
  }

  /* skip past any white-space before the value: */
  while (*(*fi) <= ' ') ++(*fi);

  /* skip past the value: */
  while (*(*fi) > ' ') ++(*fi);
}

void updateSideInfoForHuffman	(	MP3SideInfo &	sideInfo,
		Boolean	isMPEG2,
		unsigned char const *	mainDataPtr,
		unsigned	p23L0,
		unsigned	p23L1,
		unsigned &	part23Length0a,
		unsigned &	part23Length0aTruncation,
		unsigned &	part23Length0b,
		unsigned &	part23Length0bTruncation,
		unsigned &	part23Length1a,
		unsigned &	part23Length1aTruncation,
		unsigned &	part23Length1b,
		unsigned &	part23Length1bTruncation
	)

Definition at line 45 of file MP3InternalsHuffman.cpp.

References MP3HuffmanEncodingInfo::allBitOffsets, MP3SideInfo::gr_info_s::big_values, MP3HuffmanEncodingInfo::bigvalStart, MP3SideInfo::ch, debugCount, MP3SideInfo::gr, MP3HuffmanDecode(), MP3HuffmanEncodingInfo::numSamples, MP3SideInfo::gr_info_s::part2_3_length, MP3HuffmanEncodingInfo::reg1Start, and MP3HuffmanEncodingInfo::reg2Start.

Referenced by updateSideInfoSizes().

                                                                  {
  int i, j;
  unsigned sfLength, origTotABsize, adjustment;
  MP3SideInfo::gr_info_s_t* gr;

  /* First, Huffman-decode each part of the segment's main data,
     to see at which bit-boundaries the samples appear:
   */
  MP3HuffmanEncodingInfo hei;

  ++debugCount;
#ifdef DEBUG
  fprintf(stderr, "usifh-start: p23L0: %d, p23L1: %d\n", p23L0, p23L1);
#endif

  /* Process granule 0 */
  {
    gr = &(sideInfo.ch[0].gr[0]);
    origTotABsize = gr->part2_3_length;

    MP3HuffmanDecode(gr, isMPEG2, mainDataPtr, 0, origTotABsize, sfLength, hei);

    /* Begin by computing new sizes for parts a & b (& their truncations) */
#ifdef DEBUG
    fprintf(stderr, "usifh-0: %d, %d:%d, %d:%d, %d:%d, %d:%d, %d:%d\n",
            hei.numSamples,
            sfLength/8, sfLength%8,
            hei.reg1Start/8, hei.reg1Start%8,
            hei.reg2Start/8, hei.reg2Start%8,
            hei.bigvalStart/8, hei.bigvalStart%8,
            origTotABsize/8, origTotABsize%8);
#endif
    if (p23L0 < sfLength) {
      /* We can't use this, so give it all to the next granule: */
      p23L1 += p23L0;
      p23L0 = 0;
    }

    part23Length0a = hei.bigvalStart;
    part23Length0b = origTotABsize - hei.bigvalStart;
    part23Length0aTruncation = part23Length0bTruncation = 0;
    if (origTotABsize > p23L0) {
      /* We need to shorten one or both of fields a & b */
      unsigned truncation = origTotABsize - p23L0;
#ifdef TRUNC_FAIRLY
      part23Length0aTruncation  = (truncation*(part23Length0a-sfLength))
                                  /(origTotABsize-sfLength);
      part23Length0bTruncation = truncation - part23Length0aTruncation;
#endif
#ifdef TRUNC_FAVORa
      part23Length0bTruncation
        = (truncation > part23Length0b) ? part23Length0b : truncation;
      part23Length0aTruncation = truncation - part23Length0bTruncation;
#endif
#ifdef TRUNC_FAVORb
      part23Length0aTruncation  = (truncation > part23Length0a-sfLength)
        ? (part23Length0a-sfLength) : truncation;
      part23Length0bTruncation = truncation - part23Length0aTruncation;
#endif
    }
    /* ASSERT:  part23Length0xTruncation <= part23Length0x */
    part23Length0a -= part23Length0aTruncation;
    part23Length0b -= part23Length0bTruncation;
#ifdef DEBUG
    fprintf(stderr, "usifh-0: interim sizes: %d (%d), %d (%d)\n",
            part23Length0a, part23Length0aTruncation,
            part23Length0b, part23Length0bTruncation);
#endif

    /* Adjust these new lengths so they end on sample bit boundaries: */
    for (i = 0; i < (int)hei.numSamples; ++i) {
      if (hei.allBitOffsets[i] == part23Length0a) break;
      else if (hei.allBitOffsets[i] > part23Length0a) {--i; break;}
    }
    if (i < 0) { /* should happen only if we couldn't fit sfLength */
      i = 0; adjustment = 0;
    } else {
      adjustment = part23Length0a - hei.allBitOffsets[i];
    }
#ifdef DEBUG
    fprintf(stderr, "%d usifh-0: adjustment 1: %d\n", debugCount, adjustment);
#endif
    part23Length0a -= adjustment;
    part23Length0aTruncation += adjustment;
    /* Assign the bits we just shaved to field b and granule 1: */
    if (part23Length0bTruncation < adjustment) {
      p23L1 += (adjustment - part23Length0bTruncation);
      adjustment = part23Length0bTruncation;
    }
    part23Length0b += adjustment;
    part23Length0bTruncation -= adjustment;
    for (j = i; j < (int)hei.numSamples; ++j) {
      if (hei.allBitOffsets[j]
          == part23Length0a + part23Length0aTruncation + part23Length0b)
        break;
      else if (hei.allBitOffsets[j]
          > part23Length0a + part23Length0aTruncation + part23Length0b)
        {--j; break;}
    }
    if (j < 0) { /* should happen only if we couldn't fit sfLength */
      j = 0; adjustment = 0;
    } else {
      adjustment = part23Length0a+part23Length0aTruncation+part23Length0b
                   - hei.allBitOffsets[j];
    }
#ifdef DEBUG
    fprintf(stderr, "%d usifh-0: adjustment 2: %d\n", debugCount, adjustment);
#endif
    if (adjustment > part23Length0b) adjustment = part23Length0b; /*sanity*/
    part23Length0b -= adjustment;
    part23Length0bTruncation += adjustment;
    /* Assign the bits we just shaved to granule 1 */
    p23L1 += adjustment;

    if (part23Length0aTruncation > 0) {
      /* Change the granule's 'big_values' field to reflect the truncation */
      gr->big_values = i;
    }
  }

  /* Process granule 1 (MPEG-1 only) */

  if (isMPEG2) {
    part23Length1a = part23Length1b = 0;
    part23Length1aTruncation = part23Length1bTruncation = 0;
  } else {
    unsigned granule1Offset
      = origTotABsize + sideInfo.ch[1].gr[0].part2_3_length;

    gr = &(sideInfo.ch[0].gr[1]);
    origTotABsize = gr->part2_3_length;

    MP3HuffmanDecode(gr, isMPEG2, mainDataPtr, granule1Offset,
                     origTotABsize, sfLength, hei);

    /* Begin by computing new sizes for parts a & b (& their truncations) */
#ifdef DEBUG
    fprintf(stderr, "usifh-1: %d, %d:%d, %d:%d, %d:%d, %d:%d, %d:%d\n",
            hei.numSamples,
            sfLength/8, sfLength%8,
            hei.reg1Start/8, hei.reg1Start%8,
            hei.reg2Start/8, hei.reg2Start%8,
            hei.bigvalStart/8, hei.bigvalStart%8,
            origTotABsize/8, origTotABsize%8);
#endif
    if (p23L1 < sfLength) {
      /* We can't use this, so give up on this granule: */
      p23L1 = 0;
    }

    part23Length1a = hei.bigvalStart;
    part23Length1b = origTotABsize - hei.bigvalStart;
    part23Length1aTruncation = part23Length1bTruncation = 0;
    if (origTotABsize > p23L1) {
      /* We need to shorten one or both of fields a & b */
      unsigned truncation = origTotABsize - p23L1;
#ifdef TRUNC_FAIRLY
      part23Length1aTruncation  = (truncation*(part23Length1a-sfLength))
                                  /(origTotABsize-sfLength);
      part23Length1bTruncation = truncation - part23Length1aTruncation;
#endif
#ifdef TRUNC_FAVORa
      part23Length1bTruncation
        = (truncation > part23Length1b) ? part23Length1b : truncation;
      part23Length1aTruncation = truncation - part23Length1bTruncation;
#endif
#ifdef TRUNC_FAVORb
      part23Length1aTruncation  = (truncation > part23Length1a-sfLength)
        ? (part23Length1a-sfLength) : truncation;
      part23Length1bTruncation = truncation - part23Length1aTruncation;
#endif
    }
    /* ASSERT:  part23Length1xTruncation <= part23Length1x */
    part23Length1a -= part23Length1aTruncation;
    part23Length1b -= part23Length1bTruncation;
#ifdef DEBUG
    fprintf(stderr, "usifh-1: interim sizes: %d (%d), %d (%d)\n",
            part23Length1a, part23Length1aTruncation,
            part23Length1b, part23Length1bTruncation);
#endif

    /* Adjust these new lengths so they end on sample bit boundaries: */
    for (i = 0; i < (int)hei.numSamples; ++i) {
      if (hei.allBitOffsets[i] == part23Length1a) break;
      else if (hei.allBitOffsets[i] > part23Length1a) {--i; break;}
    }
    if (i < 0) { /* should happen only if we couldn't fit sfLength */
      i = 0; adjustment = 0;
    } else {
      adjustment = part23Length1a - hei.allBitOffsets[i];
    }
#ifdef DEBUG
    fprintf(stderr, "%d usifh-1: adjustment 0: %d\n", debugCount, adjustment);
#endif
    part23Length1a -= adjustment;
    part23Length1aTruncation += adjustment;
    /* Assign the bits we just shaved to field b: */
    if (part23Length1bTruncation < adjustment) {
      adjustment = part23Length1bTruncation;
    }
    part23Length1b += adjustment;
    part23Length1bTruncation -= adjustment;
    for (j = i; j < (int)hei.numSamples; ++j) {
      if (hei.allBitOffsets[j]
          == part23Length1a + part23Length1aTruncation + part23Length1b)
        break;
      else if (hei.allBitOffsets[j]
          > part23Length1a + part23Length1aTruncation + part23Length1b)
        {--j; break;}
    }
    if (j < 0) { /* should happen only if we couldn't fit sfLength */
      j = 0; adjustment = 0;
    } else {
      adjustment = part23Length1a+part23Length1aTruncation+part23Length1b
                   - hei.allBitOffsets[j];
    }
#ifdef DEBUG
    fprintf(stderr, "%d usifh-1: adjustment 1: %d\n", debugCount, adjustment);
#endif
    if (adjustment > part23Length1b) adjustment = part23Length1b; /*sanity*/
    part23Length1b -= adjustment;
    part23Length1bTruncation += adjustment;

    if (part23Length1aTruncation > 0) {
      /* Change the granule's 'big_values' field to reflect the truncation */
      gr->big_values = i;
    }
  }
#ifdef DEBUG
  fprintf(stderr, "usifh-end, new vals: %d (%d), %d (%d), %d (%d), %d (%d)\n",
          part23Length0a, part23Length0aTruncation,
          part23Length0b, part23Length0bTruncation,
          part23Length1a, part23Length1aTruncation,
          part23Length1b, part23Length1bTruncation);
#endif
}

---

Variable Documentation

unsigned debugCount = 0 [static]

Definition at line 41 of file MP3InternalsHuffman.cpp.

Referenced by updateSideInfoForHuffman().

HUFFBITS dmask = 1 << (SIZEOF_HUFFBITS*8-1)

Definition at line 608 of file MP3InternalsHuffman.cpp.

unsigned int hs = SIZEOF_HUFFBITS*8

Definition at line 609 of file MP3InternalsHuffman.cpp.

unsigned i_slen2[]

Definition at line 92 of file MP3Internals.cpp.

Referenced by MP3FrameParams::MP3FrameParams().

unsigned n_slen2[]

Definition at line 91 of file MP3Internals.cpp.

Referenced by MP3FrameParams::MP3FrameParams(), and rsf_get_scale_factors_2().

struct huffcodetab rsf_ht[HTN] [static]

Definition at line 335 of file MP3InternalsHuffman.cpp.

Referenced by MP3HuffmanDecode(), and read_decoder_table().

unsigned char const slen[2][16] [static]

Initial value:

 {
  {0, 0, 0, 0, 3, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4},
  {0, 1, 2, 3, 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 2, 3}
}

Definition at line 434 of file MP3InternalsHuffman.cpp.

Referenced by rsf_get_scale_factors_1(), and rsf_get_scale_factors_2().

unsigned char const stab[3][6][4] [static]

Initial value:

 {
  { { 6, 5, 5,5 } , { 6, 5, 7,3 } , { 11,10,0,0} ,
    { 7, 7, 7,0 } , { 6, 6, 6,3 } , {  8, 8,5,0} } ,
  { { 9, 9, 9,9 } , { 9, 9,12,6 } , { 18,18,0,0} ,
    {12,12,12,0 } , {12, 9, 9,6 } , { 15,12,9,0} } ,
  { { 6, 9, 9,9 } , { 6, 9,12,6 } , { 15,18,0,0} ,
    { 6,15,12,0 } , { 6,12, 9,6 } , {  6,18,9,0} }
}

Definition at line 439 of file MP3InternalsHuffman.cpp.

Referenced by rsf_get_scale_factors_2().

---