liveMedia/MP3Internals.cpp File Reference

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

Include dependency graph for MP3Internals.cpp:

Go to the source code of this file.

Data Structures
struct	bandInfoStruct
Defines
#define	MPG_MD_MONO   3
#define	TRUNC_FAIRLY
#define	MPG_MD_JOINT_STEREO   1
Functions
unsigned	ComputeFrameSize (unsigned bitrate, unsigned samplingFreq, Boolean usePadding, Boolean isMPEG2, unsigned char layer)
static unsigned	updateSideInfoSizes (MP3SideInfo &sideInfo, Boolean isMPEG2, unsigned char const *mainDataPtr, unsigned allowedNumBits, unsigned &part23Length0a, unsigned &part23Length0aTruncation, unsigned &part23Length0b, unsigned &part23Length0bTruncation, unsigned &part23Length1a, unsigned &part23Length1aTruncation, unsigned &part23Length1b, unsigned &part23Length1bTruncation)
Boolean	GetADUInfoFromMP3Frame (unsigned char const *framePtr, unsigned totFrameSize, unsigned &hdr, unsigned &frameSize, MP3SideInfo &sideInfo, unsigned &sideInfoSize, unsigned &backpointer, unsigned &aduSize)
static void	getSideInfo1 (MP3FrameParams &fr, MP3SideInfo &si, int stereo, int ms_stereo, long sfreq, int)
static void	getSideInfo2 (MP3FrameParams &fr, MP3SideInfo &si, int stereo, int ms_stereo, long sfreq, int)
static void	putSideInfo1 (BitVector &bv, MP3SideInfo const &si, Boolean isStereo)
static void	putSideInfo2 (BitVector &bv, MP3SideInfo const &si, Boolean isStereo)
static void	PutMP3SideInfoIntoFrame (MP3SideInfo const &si, MP3FrameParams const &fr, unsigned char *framePtr)
Boolean	ZeroOutMP3SideInfo (unsigned char *framePtr, unsigned totFrameSize, unsigned newBackpointer)
static unsigned	MP3BitrateToBitrateIndex (unsigned bitrate, Boolean isMPEG2)
static void	outputHeader (unsigned char *toPtr, unsigned hdr)
static void	assignADUBackpointer (MP3FrameParams const &fr, unsigned aduSize, MP3SideInfo &sideInfo, unsigned &availableBytesForBackpointer)
unsigned	TranscodeMP3ADU (unsigned char const *fromPtr, unsigned fromSize, unsigned toBitrate, unsigned char *toPtr, unsigned toMaxSize, unsigned &availableBytesForBackpointer)
Variables
static unsigned const	live_tabsel [2][3][16]
static long const	live_freqs [] = { 44100, 48000, 32000, 22050, 24000, 16000, 11025, 12000, 8000, 0 }
static struct bandInfoStruct const	bandInfo [7]
unsigned int	n_slen2 [512]
unsigned int	i_slen2 [256]

---

Define Documentation

#define MPG_MD_JOINT_STEREO   1

Definition at line 512 of file MP3Internals.cpp.

Referenced by MP3FrameParams::getSideInfo().

#define MPG_MD_MONO   3

Definition at line 94 of file MP3Internals.cpp.

Referenced by MP3FrameParams::setParamsFromHeader().

#define TRUNC_FAIRLY

Definition at line 233 of file MP3Internals.cpp.

---

Function Documentation

static void assignADUBackpointer	(	MP3FrameParams const &	fr,
		unsigned	aduSize,
		MP3SideInfo &	sideInfo,
		unsigned &	availableBytesForBackpointer
	)			[static]

Definition at line 682 of file MP3Internals.cpp.

References MP3FrameParams::frameSize, MP3FrameParams::isMPEG2, MP3SideInfo::main_data_begin, and MP3FrameParams::sideInfoSize.

Referenced by TranscodeMP3ADU().

                                                                         {
  // Give the ADU as large a backpointer as possible:
  unsigned maxBackpointerSize = fr.isMPEG2 ? 255 : 511;

  unsigned backpointerSize = availableBytesForBackpointer;
  if (backpointerSize > maxBackpointerSize) {
    backpointerSize = maxBackpointerSize;
  }

  // Store the new backpointer now:
  sideInfo.main_data_begin = backpointerSize;

  // Figure out how many bytes are available for the *next* ADU's backpointer:
  availableBytesForBackpointer
    = backpointerSize + fr.frameSize - fr.sideInfoSize ;
  if (availableBytesForBackpointer < aduSize) {
    availableBytesForBackpointer = 0;
  } else {
    availableBytesForBackpointer -= aduSize;
  }
}

unsigned ComputeFrameSize	(	unsigned	bitrate,
		unsigned	samplingFreq,
		Boolean	usePadding,
		Boolean	isMPEG2,
		unsigned char	layer
	)

Definition at line 219 of file MP3Internals.cpp.

Referenced by MP3FrameParams::setParamsFromHeader().

                                               {
  if (samplingFreq == 0) return 0;
  unsigned const bitrateMultiplier = (layer == 1) ? 12000*4 : 144000;
  unsigned framesize;

  framesize = bitrate*bitrateMultiplier;
  framesize /= samplingFreq<<isMPEG2;
  framesize = framesize + usePadding - 4;

  return framesize;
}

Boolean GetADUInfoFromMP3Frame	(	unsigned char const *	framePtr,
		unsigned	totFrameSize,
		unsigned &	hdr,
		unsigned &	frameSize,
		MP3SideInfo &	sideInfo,
		unsigned &	sideInfoSize,
		unsigned &	backpointer,
		unsigned &	aduSize
	)

Definition at line 303 of file MP3Internals.cpp.

References MP3SideInfo::ch, False, MP3FrameParams::frameSize, MP3FrameParams::getSideInfo(), MP3SideInfo::gr, MP3FrameParams::hdr, MP3FrameParams::layer, MP3SideInfo::main_data_begin, MP3FrameParams::setBytePointer(), MP3FrameParams::setParamsFromHeader(), MP3FrameParams::sideInfoSize, and True.

Referenced by SegmentQueue::sqAfterGettingCommon(), and TranscodeMP3ADU().

                                                                         {
  if (totFrameSize < 4) return False; // there's not enough data

  MP3FrameParams fr;
  fr.hdr =   ((unsigned)framePtr[0] << 24) | ((unsigned)framePtr[1] << 16)
           | ((unsigned)framePtr[2] << 8) | (unsigned)framePtr[3];
  fr.setParamsFromHeader();
  fr.setBytePointer(framePtr + 4, totFrameSize - 4); // skip hdr

  frameSize = 4 + fr.frameSize;

  if (fr.layer != 3) {
    // Special case for non-layer III frames
    backpointer = 0;
    sideInfoSize = 0;
    aduSize = fr.frameSize;
    return True;
  }

  sideInfoSize = fr.sideInfoSize;
  if (totFrameSize < 4 + sideInfoSize) return False; // not enough data

  fr.getSideInfo(sideInfo);

  hdr = fr.hdr;
  backpointer = sideInfo.main_data_begin;
  unsigned numBits = sideInfo.ch[0].gr[0].part2_3_length;
  numBits += sideInfo.ch[0].gr[1].part2_3_length;
  numBits += sideInfo.ch[1].gr[0].part2_3_length;
  numBits += sideInfo.ch[1].gr[1].part2_3_length;
  aduSize = (numBits+7)/8;
#ifdef DEBUG
  fprintf(stderr, "mp3GetADUInfoFromFrame: hdr: %08x, frameSize: %d, part2_3_lengths: %d,%d,%d,%d, aduSize: %d, backpointer: %d\n", hdr, frameSize, sideInfo.ch[0].gr[0].part2_3_length, sideInfo.ch[0].gr[1].part2_3_length, sideInfo.ch[1].gr[0].part2_3_length, sideInfo.ch[1].gr[1].part2_3_length, aduSize, backpointer);
#endif

  return True;
}

static void getSideInfo1	(	MP3FrameParams &	fr,
		MP3SideInfo &	si,
		int	stereo,
		int	ms_stereo,
		long	sfreq,
		int
	)			[static]

Definition at line 346 of file MP3Internals.cpp.

References bandInfo, MP3SideInfo::ch, MP3FrameParams::get1Bit(), MP3FrameParams::getBits(), MP3SideInfo::gr, bandInfoStruct::longIdx, MP3SideInfo::main_data_begin, and MP3SideInfo::private_bits.

Referenced by MP3FrameParams::getSideInfo().

                                         {
   int ch, gr;
#if 0
   int powdiff = (single == 3) ? 4 : 0;
#endif

   /* initialize all four "part2_3_length" fields to zero: */
   si.ch[0].gr[0].part2_3_length = 0; si.ch[1].gr[0].part2_3_length = 0;
   si.ch[0].gr[1].part2_3_length = 0; si.ch[1].gr[1].part2_3_length = 0;

   si.main_data_begin = fr.getBits(9);
   if (stereo == 1)
     si.private_bits = fr.getBits(5);
   else
     si.private_bits = fr.getBits(3);

   for (ch=0; ch<stereo; ch++) {
       si.ch[ch].gr[0].scfsi = -1;
       si.ch[ch].gr[1].scfsi = fr.getBits(4);
   }

   for (gr=0; gr<2; gr++) {
     for (ch=0; ch<stereo; ch++) {
       MP3SideInfo::gr_info_s_t& gr_info = si.ch[ch].gr[gr];

       gr_info.part2_3_length = fr.getBits(12);
       gr_info.big_values = fr.getBits(9);
       gr_info.global_gain = fr.getBits(8);
#if 0
       gr_info.pow2gain = gainpow2+256 - gr_info.global_gain + powdiff;
       if (ms_stereo) gr_info.pow2gain += 2;
#endif
       gr_info.scalefac_compress = fr.getBits(4);
/* window-switching flag == 1 for block_Type != 0 .. and block-type == 0 -> win-sw-flag = 0 */
       gr_info.window_switching_flag = fr.get1Bit();
       if (gr_info.window_switching_flag) {
         int i;
         gr_info.block_type = fr.getBits(2);
         gr_info.mixed_block_flag = fr.get1Bit();
         gr_info.table_select[0] = fr.getBits(5);
         gr_info.table_select[1] = fr.getBits(5);
         /*
          * table_select[2] not needed, because there is no region2,
          * but to satisfy some verifications tools we set it either.
          */
         gr_info.table_select[2] = 0;
         for (i=0;i<3;i++) {
           gr_info.subblock_gain[i] = fr.getBits(3);
           gr_info.full_gain[i]
             = gr_info.pow2gain + ((gr_info.subblock_gain[i])<<3);
         }

#ifdef DEBUG_ERRORS
         if (gr_info.block_type == 0) {
           fprintf(stderr,"Blocktype == 0 and window-switching == 1 not allowed.\n");
         }
#endif
         /* region_count/start parameters are implicit in this case. */
         gr_info.region1start = 36>>1;
         gr_info.region2start = 576>>1;
       }
       else
       {
         int i,r0c,r1c;
         for (i=0; i<3; i++) {
           gr_info.table_select[i] = fr.getBits(5);
         }
         r0c = gr_info.region0_count = fr.getBits(4);
         r1c = gr_info.region1_count = fr.getBits(3);
         gr_info.region1start = bandInfo[sfreq].longIdx[r0c+1] >> 1 ;
         gr_info.region2start = bandInfo[sfreq].longIdx[r0c+1+r1c+1] >> 1;
         gr_info.block_type = 0;
         gr_info.mixed_block_flag = 0;
       }
       gr_info.preflag = fr.get1Bit();
       gr_info.scalefac_scale = fr.get1Bit();
       gr_info.count1table_select = fr.get1Bit();
     }
   }
}

static void getSideInfo2	(	MP3FrameParams &	fr,
		MP3SideInfo &	si,
		int	stereo,
		int	ms_stereo,
		long	sfreq,
		int
	)			[static]

Definition at line 429 of file MP3Internals.cpp.

References bandInfo, MP3SideInfo::ch, MP3FrameParams::get1Bit(), MP3FrameParams::getBits(), MP3SideInfo::gr, bandInfoStruct::longIdx, MP3SideInfo::main_data_begin, and MP3SideInfo::private_bits.

Referenced by MP3FrameParams::getSideInfo().

                                         {
   int ch;
#if 0
   int powdiff = (single == 3) ? 4 : 0;
#endif

   /* initialize all four "part2_3_length" fields to zero: */
   si.ch[0].gr[0].part2_3_length = 0; si.ch[1].gr[0].part2_3_length = 0;
   si.ch[0].gr[1].part2_3_length = 0; si.ch[1].gr[1].part2_3_length = 0;

   si.main_data_begin = fr.getBits(8);
   if (stereo == 1)
     si.private_bits = fr.get1Bit();
   else
     si.private_bits = fr.getBits(2);

   for (ch=0; ch<stereo; ch++) {
       MP3SideInfo::gr_info_s_t& gr_info = si.ch[ch].gr[0];

       gr_info.part2_3_length = fr.getBits(12);
       si.ch[ch].gr[1].part2_3_length = 0; /* to ensure granule 1 unused */

       gr_info.big_values = fr.getBits(9);
       gr_info.global_gain = fr.getBits(8);
#if 0
       gr_info.pow2gain = gainpow2+256 - gr_info.global_gain + powdiff;
       if (ms_stereo) gr_info.pow2gain += 2;
#endif
       gr_info.scalefac_compress = fr.getBits(9);
/* window-switching flag == 1 for block_Type != 0 .. and block-type == 0 -> win-sw-flag = 0 */
       gr_info.window_switching_flag = fr.get1Bit();
       if (gr_info.window_switching_flag) {
         int i;
         gr_info.block_type = fr.getBits(2);
         gr_info.mixed_block_flag = fr.get1Bit();
         gr_info.table_select[0] = fr.getBits(5);
         gr_info.table_select[1] = fr.getBits(5);
         /*
          * table_select[2] not needed, because there is no region2,
          * but to satisfy some verifications tools we set it either.
          */
         gr_info.table_select[2] = 0;
         for (i=0;i<3;i++) {
           gr_info.subblock_gain[i] = fr.getBits(3);
           gr_info.full_gain[i]
             = gr_info.pow2gain + ((gr_info.subblock_gain[i])<<3);
         }

#ifdef DEBUG_ERRORS
         if (gr_info.block_type == 0) {
           fprintf(stderr,"Blocktype == 0 and window-switching == 1 not allowed.\n");
         }
#endif
         /* region_count/start parameters are implicit in this case. */
/* check this again! */
         if (gr_info.block_type == 2)
           gr_info.region1start = 36>>1;
         else {
           gr_info.region1start = 54>>1;
         }
         gr_info.region2start = 576>>1;
       }
       else
       {
         int i,r0c,r1c;
         for (i=0; i<3; i++) {
           gr_info.table_select[i] = fr.getBits(5);
         }
         r0c = gr_info.region0_count = fr.getBits(4);
         r1c = gr_info.region1_count = fr.getBits(3);
         gr_info.region1start = bandInfo[sfreq].longIdx[r0c+1] >> 1 ;
         gr_info.region2start = bandInfo[sfreq].longIdx[r0c+1+r1c+1] >> 1;
         gr_info.block_type = 0;
         gr_info.mixed_block_flag = 0;
       }
       gr_info.scalefac_scale = fr.get1Bit();
       gr_info.count1table_select = fr.get1Bit();
   }
}

static unsigned MP3BitrateToBitrateIndex	(	unsigned	bitrate,
		Boolean	isMPEG2
	)			[static]

Definition at line 664 of file MP3Internals.cpp.

References live_tabsel.

Referenced by TranscodeMP3ADU().

                                                          {
  for (unsigned i = 1; i < 15; ++i) {
    if (live_tabsel[isMPEG2][2][i] >= bitrate)
      return i;
  }

  // "bitrate" was larger than any possible, so return the largest possible:
  return 14;
}

static void outputHeader	(	unsigned char *	toPtr,
		unsigned	hdr
	)			[static]

Definition at line 675 of file MP3Internals.cpp.

Referenced by TranscodeMP3ADU().

                                                             {
  toPtr[0] = (unsigned char)(hdr>>24);
  toPtr[1] = (unsigned char)(hdr>>16);
  toPtr[2] = (unsigned char)(hdr>>8);
  toPtr[3] = (unsigned char)(hdr);
}

static void PutMP3SideInfoIntoFrame	(	MP3SideInfo const &	si,
		MP3FrameParams const &	fr,
		unsigned char *	framePtr
	)			[static]

Definition at line 621 of file MP3Internals.cpp.

References MP3FrameParams::bv, MP3FrameParams::hasCRC, MP3FrameParams::isMPEG2, MP3FrameParams::isStereo, putSideInfo1(), putSideInfo2(), and MP3FrameParams::sideInfoSize.

Referenced by TranscodeMP3ADU(), and ZeroOutMP3SideInfo().

                                                             {
  if (fr.hasCRC) framePtr += 2; // skip CRC

  BitVector bv(framePtr, 0, 8*fr.sideInfoSize);

  if (fr.isMPEG2) {
    putSideInfo2(bv, si, fr.isStereo);
  } else {
    putSideInfo1(bv, si, fr.isStereo);
  }
}

static void putSideInfo1	(	BitVector &	bv,
		MP3SideInfo const &	si,
		Boolean	isStereo
	)			[static]

Definition at line 536 of file MP3Internals.cpp.

References MP3FrameParams::bv, MP3SideInfo::ch, MP3SideInfo::gr, MP3SideInfo::main_data_begin, MP3SideInfo::private_bits, BitVector::put1Bit(), BitVector::putBits(), and MP3FrameParams::stereo.

Referenced by PutMP3SideInfoIntoFrame().

                                                                  {
  int ch, gr, i;
  int stereo = isStereo ? 2 : 1;

  bv.putBits(si.main_data_begin,9);
  if (stereo == 1)
    bv.putBits(si.private_bits, 5);
  else
    bv.putBits(si.private_bits, 3);

  for (ch=0; ch<stereo; ch++) {
    bv.putBits(si.ch[ch].gr[1].scfsi, 4);
  }

  for (gr=0; gr<2; gr++) {
    for (ch=0; ch<stereo; ch++) {
      MP3SideInfo::gr_info_s_t const& gr_info = si.ch[ch].gr[gr];

      bv.putBits(gr_info.part2_3_length, 12);
      bv.putBits(gr_info.big_values, 9);
      bv.putBits(gr_info.global_gain, 8);
      bv.putBits(gr_info.scalefac_compress, 4);
      bv.put1Bit(gr_info.window_switching_flag);
      if (gr_info.window_switching_flag) {
        bv.putBits(gr_info.block_type, 2);
        bv.put1Bit(gr_info.mixed_block_flag);
        for (i=0; i<2; i++)
          bv.putBits(gr_info.table_select[i], 5);
        for (i=0; i<3; i++)
          bv.putBits(gr_info.subblock_gain[i], 3);
      }
      else {
        for (i=0; i<3; i++)
          bv.putBits(gr_info.table_select[i], 5);
        bv.putBits(gr_info.region0_count, 4);
        bv.putBits(gr_info.region1_count, 3);
      }

      bv.put1Bit(gr_info.preflag);
      bv.put1Bit(gr_info.scalefac_scale);
      bv.put1Bit(gr_info.count1table_select);
    }
  }
}

static void putSideInfo2	(	BitVector &	bv,
		MP3SideInfo const &	si,
		Boolean	isStereo
	)			[static]

Definition at line 582 of file MP3Internals.cpp.

References MP3FrameParams::bv, MP3SideInfo::ch, MP3SideInfo::gr, MP3SideInfo::main_data_begin, MP3SideInfo::private_bits, BitVector::put1Bit(), BitVector::putBits(), and MP3FrameParams::stereo.

Referenced by PutMP3SideInfoIntoFrame().

                                                                  {
  int ch, i;
  int stereo = isStereo ? 2 : 1;

  bv.putBits(si.main_data_begin,8);
  if (stereo == 1)
    bv.put1Bit(si.private_bits);
  else
    bv.putBits(si.private_bits, 2);

  for (ch=0; ch<stereo; ch++) {
    MP3SideInfo::gr_info_s_t const& gr_info = si.ch[ch].gr[0];

    bv.putBits(gr_info.part2_3_length, 12);
    bv.putBits(gr_info.big_values, 9);
    bv.putBits(gr_info.global_gain, 8);
    bv.putBits(gr_info.scalefac_compress, 9);
    bv.put1Bit(gr_info.window_switching_flag);
    if (gr_info.window_switching_flag) {
      bv.putBits(gr_info.block_type, 2);
      bv.put1Bit(gr_info.mixed_block_flag);
      for (i=0; i<2; i++)
        bv.putBits(gr_info.table_select[i], 5);
      for (i=0; i<3; i++)
        bv.putBits(gr_info.subblock_gain[i], 3);
    }
    else {
      for (i=0; i<3; i++)
        bv.putBits(gr_info.table_select[i], 5);
      bv.putBits(gr_info.region0_count, 4);
      bv.putBits(gr_info.region1_count, 3);
    }

    bv.put1Bit(gr_info.scalefac_scale);
    bv.put1Bit(gr_info.count1table_select);
  }
}

unsigned TranscodeMP3ADU	(	unsigned char const *	fromPtr,
		unsigned	fromSize,
		unsigned	toBitrate,
		unsigned char *	toPtr,
		unsigned	toMaxSize,
		unsigned &	availableBytesForBackpointer
	)

Definition at line 707 of file MP3Internals.cpp.

References assignADUBackpointer(), MP3FrameParams::frameSize, GetADUInfoFromMP3Frame(), MP3FrameParams::hdr, MP3FrameParams::isMPEG2, MP3BitrateToBitrateIndex(), outputHeader(), PutMP3SideInfoIntoFrame(), MP3FrameParams::setParamsFromHeader(), shiftBits(), MP3FrameParams::sideInfoSize, and updateSideInfoSizes().

Referenced by MP3ADUTranscoder::afterGettingFrame1().

                                                              {
  // Begin by parsing the input ADU's parameters:
  unsigned hdr, inFrameSize, inSideInfoSize, backpointer, inAduSize;
  MP3SideInfo sideInfo;
  if (!GetADUInfoFromMP3Frame(fromPtr, fromSize,
                              hdr, inFrameSize, sideInfo, inSideInfoSize,
                              backpointer, inAduSize)) {
    return 0;
  }
  fromPtr += (4+inSideInfoSize); // skip to 'main data'

  // Alter the 4-byte MPEG header to reflect the output ADU:
  // (different bitrate; mono; no CRC)
  Boolean isMPEG2 = ((hdr&0x00080000) == 0);
  unsigned toBitrateIndex = MP3BitrateToBitrateIndex(toBitrate, isMPEG2);
  hdr &=~ 0xF000; hdr |= (toBitrateIndex<<12); // set bitrate index
  hdr |= 0x10200; // turn on !error-prot and padding bits
  hdr &=~ 0xC0; hdr |= 0xC0; // set mode to 3 (mono)

  // Set up the rest of the parameters of the new ADU:
  MP3FrameParams outFr;
  outFr.hdr = hdr;
  outFr.setParamsFromHeader();

  // Figure out how big to make the output ADU:
  unsigned inAveAduSize = inFrameSize - inSideInfoSize;
  unsigned outAveAduSize = outFr.frameSize - outFr.sideInfoSize;
  unsigned desiredOutAduSize /*=inAduSize*outAveAduSize/inAveAduSize*/
    = (2*inAduSize*outAveAduSize + inAveAduSize)/(2*inAveAduSize);
      // this rounds to the nearest integer

  if (toMaxSize < (4 + outFr.sideInfoSize)) return 0;
  unsigned maxOutAduSize = toMaxSize - (4 + outFr.sideInfoSize);
  if (desiredOutAduSize > maxOutAduSize) {
    desiredOutAduSize = maxOutAduSize;
  }

  // Figure out the new sizes of the various 'part23 lengths',
  // and how much they are truncated:
  unsigned part23Length0a, part23Length0aTruncation;
  unsigned part23Length0b, part23Length0bTruncation;
  unsigned part23Length1a, part23Length1aTruncation;
  unsigned part23Length1b, part23Length1bTruncation;
  unsigned numAduBits
    = updateSideInfoSizes(sideInfo, outFr.isMPEG2,
                          fromPtr, 8*desiredOutAduSize,
                          part23Length0a, part23Length0aTruncation,
                          part23Length0b, part23Length0bTruncation,
                          part23Length1a, part23Length1aTruncation,
                          part23Length1b, part23Length1bTruncation);
#ifdef DEBUG
fprintf(stderr, "shrinkage %d->%d [(%d,%d),(%d,%d)] (trunc: [(%d,%d),(%d,%d)]) {%d}\n", inAduSize, (numAduBits+7)/8,
              part23Length0a, part23Length0b, part23Length1a, part23Length1b,
              part23Length0aTruncation, part23Length0bTruncation,
              part23Length1aTruncation, part23Length1bTruncation,
              maxOutAduSize);
#endif
 unsigned actualOutAduSize = (numAduBits+7)/8;

 // Give the new ADU an appropriate 'backpointer':
 assignADUBackpointer(outFr, actualOutAduSize, sideInfo, availableBytesForBackpointer);


 // 4-byte header
 outputHeader(toPtr, hdr); toPtr += 4;

 // side info
 PutMP3SideInfoIntoFrame(sideInfo, outFr, toPtr); toPtr += outFr.sideInfoSize;

 // 'main data', using the new lengths
 unsigned toBitOffset = 0;
 unsigned fromBitOffset = 0;

 /* rebuild portion 0a: */
 memmove(toPtr, fromPtr, (part23Length0a+7)/8);
 toBitOffset += part23Length0a;
 fromBitOffset += part23Length0a + part23Length0aTruncation;

 /* rebuild portion 0b: */
 shiftBits(toPtr, toBitOffset, fromPtr, fromBitOffset, part23Length0b);
 toBitOffset += part23Length0b;
 fromBitOffset += part23Length0b + part23Length0bTruncation;

 /* rebuild portion 1a: */
 shiftBits(toPtr, toBitOffset, fromPtr, fromBitOffset, part23Length1a);
 toBitOffset += part23Length1a;
 fromBitOffset += part23Length1a + part23Length1aTruncation;

 /* rebuild portion 1b: */
 shiftBits(toPtr, toBitOffset, fromPtr, fromBitOffset, part23Length1b);
 toBitOffset += part23Length1b;

 /* zero out any remaining bits (probably unnecessary, but...) */
 unsigned char const zero = '\0';
 shiftBits(toPtr, toBitOffset, &zero, 0,
           actualOutAduSize*8 - numAduBits);

 return 4 + outFr.sideInfoSize + actualOutAduSize;
}

static unsigned updateSideInfoSizes	(	MP3SideInfo &	sideInfo,
		Boolean	isMPEG2,
		unsigned char const *	mainDataPtr,
		unsigned	allowedNumBits,
		unsigned &	part23Length0a,
		unsigned &	part23Length0aTruncation,
		unsigned &	part23Length0b,
		unsigned &	part23Length0bTruncation,
		unsigned &	part23Length1a,
		unsigned &	part23Length1aTruncation,
		unsigned &	part23Length1b,
		unsigned &	part23Length1bTruncation
	)			[static]

Definition at line 234 of file MP3Internals.cpp.

References MP3SideInfo::ch, MP3SideInfo::gr, and updateSideInfoForHuffman().

Referenced by TranscodeMP3ADU().

                                                                        {
  unsigned p23L0, p23L1 = 0, p23L0Trunc = 0, p23L1Trunc = 0;

  p23L0 = sideInfo.ch[0].gr[0].part2_3_length;
  p23L1 = isMPEG2 ? 0 : sideInfo.ch[0].gr[1].part2_3_length;
#ifdef TRUNC_ONLY0
  if (p23L0 < allowedNumBits)
    allowedNumBits = p23L0;
#endif
#ifdef TRUNC_ONLY1
  if (p23L1 < allowedNumBits)
    allowedNumBits = p23L1;
#endif
  if (p23L0 + p23L1 > allowedNumBits) {
    /* We need to shorten one or both fields */
    unsigned truncation = p23L0 + p23L1 - allowedNumBits;
#ifdef TRUNC_FAIRLY
    p23L0Trunc = (truncation*p23L0)/(p23L0 + p23L1);
    p23L1Trunc = truncation - p23L0Trunc;
#endif
#if defined(TRUNC_FAVOR0) || defined(TRUNC_ONLY0)
    p23L1Trunc = (truncation>p23L1) ? p23L1 : truncation;
    p23L0Trunc = truncation - p23L1Trunc;
#endif
#if defined(TRUNC_FAVOR1) || defined(TRUNC_ONLY1)
    p23L0Trunc = (truncation>p23L0) ? p23L0 : truncation;
    p23L1Trunc = truncation - p23L0Trunc;
#endif
  }

  /* ASSERT: (p23L0Trunc <= p23L0) && (p23l1Trunc <= p23L1) */
  p23L0 -= p23L0Trunc; p23L1 -= p23L1Trunc;
#ifdef DEBUG
  fprintf(stderr, "updateSideInfoSizes (allowed: %d): %d->%d, %d->%d\n", allowedNumBits, p23L0+p23L0Trunc, p23L0, p23L1+p23L1Trunc, p23L1);
#endif

  // The truncations computed above are still estimates.  We need to
  // adjust them so that the new fields will continue to end on
  // Huffman-encoded sample boundaries:
  updateSideInfoForHuffman(sideInfo, isMPEG2, mainDataPtr,
                           p23L0, p23L1,
                           part23Length0a, part23Length0aTruncation,
                           part23Length0b, part23Length0bTruncation,
                           part23Length1a, part23Length1aTruncation,
                           part23Length1b, part23Length1bTruncation);
  p23L0 = part23Length0a + part23Length0b;
  p23L1 = part23Length1a + part23Length1b;

  sideInfo.ch[0].gr[0].part2_3_length = p23L0;
  sideInfo.ch[0].gr[1].part2_3_length = p23L1;
  part23Length0bTruncation
    += sideInfo.ch[1].gr[0].part2_3_length; /* allow for stereo */
  sideInfo.ch[1].gr[0].part2_3_length = 0; /* output mono */
  sideInfo.ch[1].gr[1].part2_3_length = 0; /* output mono */

  return p23L0 + p23L1;
}

Boolean ZeroOutMP3SideInfo	(	unsigned char *	framePtr,
		unsigned	totFrameSize,
		unsigned	newBackpointer
	)

Definition at line 636 of file MP3Internals.cpp.

References MP3SideInfo::ch, False, MP3FrameParams::getSideInfo(), MP3SideInfo::gr, MP3FrameParams::hdr, MP3SideInfo::main_data_begin, PutMP3SideInfoIntoFrame(), MP3FrameParams::setBytePointer(), MP3FrameParams::setParamsFromHeader(), MP3FrameParams::sideInfoSize, and True.

Referenced by SegmentQueue::insertDummyBeforeTail().

                                                    {
  if (totFrameSize < 4) return False; // there's not enough data

  MP3FrameParams fr;
  fr.hdr =   ((unsigned)framePtr[0] << 24) | ((unsigned)framePtr[1] << 16)
           | ((unsigned)framePtr[2] << 8) | (unsigned)framePtr[3];
  fr.setParamsFromHeader();
  fr.setBytePointer(framePtr + 4, totFrameSize - 4); // skip hdr

  if (totFrameSize < 4 + fr.sideInfoSize) return False; // not enough data

  MP3SideInfo si;
  fr.getSideInfo(si);

  si.main_data_begin = newBackpointer; /* backpointer */
  /* set all four "part2_3_length" and "big_values" fields to zero: */
  si.ch[0].gr[0].part2_3_length = si.ch[0].gr[0].big_values = 0;
  si.ch[1].gr[0].part2_3_length = si.ch[1].gr[0].big_values = 0;
  si.ch[0].gr[1].part2_3_length = si.ch[0].gr[1].big_values = 0;
  si.ch[1].gr[1].part2_3_length = si.ch[1].gr[1].big_values = 0;

  PutMP3SideInfoIntoFrame(si, fr, framePtr + 4);

  return True;
}

---

Variable Documentation

struct bandInfoStruct const bandInfo[7] [static]

Definition at line 51 of file MP3Internals.cpp.

Referenced by getSideInfo1(), and getSideInfo2().

unsigned int i_slen2[256]

Definition at line 92 of file MP3Internals.cpp.

Referenced by MP3FrameParams::MP3FrameParams().

long const live_freqs[] = { 44100, 48000, 32000, 22050, 24000, 16000, 11025, 12000, 8000, 0 } [static]

Definition at line 42 of file MP3Internals.cpp.

Referenced by MP3FrameParams::setParamsFromHeader().

unsigned const live_tabsel[2][3][16] [static]

Initial value:

 {
   { {32,32,64,96,128,160,192,224,256,288,320,352,384,416,448,448},
     {32,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,384},
     {32,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,320} },

   { {32,32,48,56,64,80,96,112,128,144,160,176,192,224,256,256},
     {8,8,16,24,32,40,48,56,64,80,96,112,128,144,160,160},
     {8,8,16,24,32,40,48,56,64,80,96,112,128,144,160,160} }
}

Definition at line 30 of file MP3Internals.cpp.

Referenced by MP3BitrateToBitrateIndex(), and MP3FrameParams::setParamsFromHeader().

unsigned int n_slen2[512]

Definition at line 91 of file MP3Internals.cpp.

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

---