MP3FrameParams Class Reference

#include <MP3Internals.hh>

Collaboration diagram for MP3FrameParams:


Public Member Functions
	MP3FrameParams ()
	~MP3FrameParams ()
void	setParamsFromHeader ()
void	setBytePointer (unsigned char const *restOfFrame, unsigned totNumBytes)
void	getSideInfo (MP3SideInfo &si)
unsigned	getBits (unsigned numBits)
unsigned	get1Bit ()
Data Fields
unsigned	hdr
unsigned char	frameBytes [MAX_MP3_FRAME_SIZE]
Boolean	isMPEG2
unsigned	layer
unsigned	bitrate
unsigned	samplingFreq
Boolean	isStereo
Boolean	isFreeFormat
unsigned	frameSize
unsigned	sideInfoSize
Boolean	hasCRC
unsigned	oldHdr
unsigned	firstHdr
Private Member Functions
unsigned	computeSideInfoSize ()
Private Attributes
BitVector	bv
unsigned	bitrateIndex
unsigned	samplingFreqIndex
Boolean	isMPEG2_5
Boolean	padding
Boolean	extension
unsigned	mode
unsigned	mode_ext
Boolean	copyright
Boolean	original
unsigned	emphasis
unsigned	stereo

Detailed Description

Definition at line 66 of file MP3Internals.hh.

Constructor & Destructor Documentation

MP3FrameParams::MP3FrameParams ( )

Definition at line 99 of file MP3Internals.cpp.

References False, firstHdr, i_slen2, n_slen2, oldHdr, and True.

00100   : bv(frameBytes, 0, sizeof frameBytes) /* by default */ {
00101   oldHdr = firstHdr = 0;
00102 
00103   static Boolean doneInit = False;
00104   if (doneInit) return;
00105 
00106   int i,j,k,l;
00107 
00108   for (i=0;i<5;i++) {
00109     for (j=0;j<6;j++) {
00110       for (k=0;k<6;k++) {
00111         int n = k + j * 6 + i * 36;
00112         i_slen2[n] = i|(j<<3)|(k<<6)|(3<<12);
00113       }
00114     }
00115   }
00116   for (i=0;i<4;i++) {
00117     for (j=0;j<4;j++) {
00118       for (k=0;k<4;k++) {
00119         int n = k + j * 4 + i * 16;
00120         i_slen2[n+180] = i|(j<<3)|(k<<6)|(4<<12);
00121       }
00122     }
00123   }
00124   for (i=0;i<4;i++) {
00125     for (j=0;j<3;j++) {
00126       int n = j + i * 3;
00127       i_slen2[n+244] = i|(j<<3) | (5<<12);
00128       n_slen2[n+500] = i|(j<<3) | (2<<12) | (1<<15);
00129     }
00130   }
00131 
00132   for (i=0;i<5;i++) {
00133     for (j=0;j<5;j++) {
00134       for (k=0;k<4;k++) {
00135         for (l=0;l<4;l++) {
00136           int n = l + k * 4 + j * 16 + i * 80;
00137           n_slen2[n] = i|(j<<3)|(k<<6)|(l<<9)|(0<<12);
00138         }
00139       }
00140     }
00141   }
00142   for (i=0;i<5;i++) {
00143     for (j=0;j<5;j++) {
00144       for (k=0;k<4;k++) {
00145         int n = k + j * 4 + i * 20;
00146         n_slen2[n+400] = i|(j<<3)|(k<<6)|(1<<12);
00147       }
00148     }
00149   }
00150   doneInit = True;
00151 }

MP3FrameParams::~MP3FrameParams ( )

Definition at line 153 of file MP3Internals.cpp.

00153                                 {
00154 }

Member Function Documentation

void MP3FrameParams::setParamsFromHeader ( )

Definition at line 156 of file MP3Internals.cpp.

References bitrate, bitrateIndex, ComputeFrameSize(), computeSideInfoSize(), copyright, emphasis, extension, frameSize, hasCRC, hdr, isFreeFormat, isMPEG2, isMPEG2_5, isStereo, layer, live_freqs, live_tabsel, mode, mode_ext, MPG_MD_MONO, original, padding, samplingFreq, samplingFreqIndex, sideInfoSize, and stereo.

Referenced by MP3StreamState::findNextFrame(), GetADUInfoFromMP3Frame(), MPEG1or2AudioStreamParser::parse(), TranscodeMP3ADU(), and ZeroOutMP3SideInfo().

00156                                          {
00157   if (hdr & (1<<20)) {
00158     isMPEG2 = (hdr & (1<<19)) ? 0x0 : 0x1;
00159     isMPEG2_5 = 0;
00160   }
00161   else {
00162     isMPEG2 = 1;
00163     isMPEG2_5 = 1;
00164   }
00165 
00166   layer = 4-((hdr>>17)&3);
00167   if (layer == 4) layer = 3; // layer==4 is not allowed
00168   bitrateIndex = ((hdr>>12)&0xf);
00169 
00170   if (isMPEG2_5) {
00171     samplingFreqIndex = ((hdr>>10)&0x3) + 6;
00172   } else {
00173     samplingFreqIndex = ((hdr>>10)&0x3) + (isMPEG2*3);
00174   }
00175 
00176   hasCRC = (hdr & 0x10000) == 0;
00177 
00178   padding   = ((hdr>>9)&0x1);
00179   extension = ((hdr>>8)&0x1);
00180   mode      = ((hdr>>6)&0x3);
00181   mode_ext  = ((hdr>>4)&0x3);
00182   copyright = ((hdr>>3)&0x1);
00183   original  = ((hdr>>2)&0x1);
00184   emphasis  = hdr & 0x3;
00185 
00186   stereo    = (mode == MPG_MD_MONO) ? 1 : 2;
00187 
00188   if (((hdr>>10)&0x3) == 0x3) {
00189 #ifdef DEBUG_ERRORS
00190     fprintf(stderr,"Stream error - hdr: 0x%08x\n", hdr);
00191 #endif
00192   }
00193 
00194   bitrate = live_tabsel[isMPEG2][layer-1][bitrateIndex];
00195   samplingFreq = live_freqs[samplingFreqIndex];
00196   isStereo = (stereo > 1);
00197   isFreeFormat = (bitrateIndex == 0);
00198   frameSize
00199     = ComputeFrameSize(bitrate, samplingFreq, padding, isMPEG2, layer);
00200   sideInfoSize = computeSideInfoSize();
00201  }

void MP3FrameParams::setBytePointer	(	unsigned char const *	restOfFrame,
		unsigned	totNumBytes
	)			`[inline]`

Definition at line 89 of file MP3Internals.hh.

References bv, and BitVector::setup().

Referenced by MP3StreamState::findNextFrame(), GetADUInfoFromMP3Frame(), and ZeroOutMP3SideInfo().

00090                                             {// called during setup
00091     bv.setup((unsigned char*)restOfFrame, 0, 8*totNumBytes);
00092   }

void MP3FrameParams::getSideInfo ( MP3SideInfo & si )

Definition at line 514 of file MP3Internals.cpp.

References getBits(), getSideInfo1(), getSideInfo2(), hasCRC, isMPEG2, mode, mode_ext, MPG_MD_JOINT_STEREO, samplingFreqIndex, and stereo.

Referenced by GetADUInfoFromMP3Frame(), and ZeroOutMP3SideInfo().

00514                                                 {
00515   // First skip over the CRC if present:
00516   if (hasCRC) getBits(16);
00517 
00518   int single = -1;
00519   int ms_stereo;
00520   int sfreq = samplingFreqIndex;
00521 
00522   if (stereo == 1) {
00523     single = 0;
00524   }
00525 
00526   ms_stereo = (mode == MPG_MD_JOINT_STEREO) && (mode_ext & 0x2);
00527 
00528   if (isMPEG2) {
00529     getSideInfo2(*this, si, stereo, ms_stereo, sfreq, single);
00530   } else {
00531     getSideInfo1(*this, si, stereo, ms_stereo, sfreq, single);
00532   }
00533 }

unsigned MP3FrameParams::getBits ( unsigned numBits ) [inline]

Definition at line 101 of file MP3Internals.hh.

References bv, and BitVector::getBits().

Referenced by getSideInfo(), getSideInfo1(), and getSideInfo2().

00101 { return bv.getBits(numBits); }

unsigned MP3FrameParams::get1Bit ( ) [inline]

Definition at line 102 of file MP3Internals.hh.

References bv, and BitVector::get1Bit().

Referenced by getSideInfo1(), and getSideInfo2().

00102 { return bv.get1Bit(); }

unsigned MP3FrameParams::computeSideInfoSize ( ) [private]

Definition at line 203 of file MP3Internals.cpp.

References hasCRC, isMPEG2, isStereo, and size.

Referenced by setParamsFromHeader().

00203                                              {
00204   unsigned size;
00205 
00206   if (isMPEG2) {
00207     size = isStereo ? 17 : 9;
00208   } else {
00209     size = isStereo ? 32 : 17;
00210   }
00211 
00212   if (hasCRC) {
00213     size += 2;
00214   }
00215 
00216   return size;
00217 }