libMpegTPDec/src/tpdec_adts.cpp

   1
   2 /* -----------------------------------------------------------------------------------------------------------
   3 Software License for The Fraunhofer FDK AAC Codec Library for Android
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  73 5.    CONTACT INFORMATION
  74
  75 Fraunhofer Institute for Integrated Circuits IIS
  76 Attention: Audio and Multimedia Departments - FDK AAC LL
  77 Am Wolfsmantel 33
  78 91058 Erlangen, Germany
  79
  80 www.iis.fraunhofer.de/amm
  81 amm-info@iis.fraunhofer.de
  82 ----------------------------------------------------------------------------------------------------------- */
  83
  84 /*****************************  MPEG-4 AAC Decoder  **************************
  85
  86    Author(s):   Josef Hoepfl
  87    Description: ADTS interface
  88
  89 ******************************************************************************/
  90
  91 #include "tpdec_adts.h"
  92
  93
  94 #include "FDK_bitstream.h"
  95
  96
  97
  98 void adtsRead_CrcInit(HANDLE_ADTS pAdts) /*!< pointer to adts crc info stucture */
  99 {
 100   FDKcrcInit(&pAdts->crcInfo, 0x8005, 0xFFFF, 16);
 101 }
 102
 103 int adtsRead_CrcStartReg(
 104                      HANDLE_ADTS pAdts,          /*!< pointer to adts stucture */
 105                      HANDLE_FDK_BITSTREAM hBs,   /*!< handle to current bit buffer structure */
 106                      int mBits                   /*!< number of bits in crc region */
 107                    )
 108 {
 109   if (pAdts->bs.protection_absent) {
 110     return 0;
 111   }
 112
 113   return ( FDKcrcStartReg(&pAdts->crcInfo, hBs, mBits) );
 114
 115 }
 116
 117 void adtsRead_CrcEndReg(
 118                     HANDLE_ADTS pAdts, /*!< pointer to adts crc info stucture */
 119                     HANDLE_FDK_BITSTREAM hBs,   /*!< handle to current bit buffer structure */
 120                     int reg                    /*!< crc region */
 121                   )
 122 {
 123   if (pAdts->bs.protection_absent == 0)
 124   {
 125     FDKcrcEndReg(&pAdts->crcInfo, hBs, reg);
 126   }
 127 }
 128
 129 TRANSPORTDEC_ERROR adtsRead_CrcCheck( HANDLE_ADTS pAdts )
 130 {
 131   TRANSPORTDEC_ERROR ErrorStatus = TRANSPORTDEC_OK;
 132   USHORT crc;
 133
 134   if (pAdts->bs.protection_absent)
 135     return TRANSPORTDEC_OK;
 136
 137   crc = FDKcrcGetCRC(&pAdts->crcInfo);
 138   if (crc != pAdts->crcReadValue)
 139   {
 140     return (TRANSPORTDEC_CRC_ERROR);
 141   }
 142
 143   return (ErrorStatus);
 144 }
 145
 146
 147
 148 #define Adts_Length_SyncWord                     12
 149 #define Adts_Length_Id                            1
 150 #define Adts_Length_Layer                         2
 151 #define Adts_Length_ProtectionAbsent              1
 152 #define Adts_Length_Profile                       2
 153 #define Adts_Length_SamplingFrequencyIndex        4
 154 #define Adts_Length_PrivateBit                    1
 155 #define Adts_Length_ChannelConfiguration          3
 156 #define Adts_Length_OriginalCopy                  1
 157 #define Adts_Length_Home                          1
 158 #define Adts_Length_CopyrightIdentificationBit    1
 159 #define Adts_Length_CopyrightIdentificationStart  1
 160 #define Adts_Length_FrameLength                  13
 161 #define Adts_Length_BufferFullness               11
 162 #define Adts_Length_NumberOfRawDataBlocksInFrame  2
 163 #define Adts_Length_CrcCheck                     16
 164
 165 TRANSPORTDEC_ERROR adtsRead_DecodeHeader(
 166         HANDLE_ADTS           pAdts,
 167         CSAudioSpecificConfig *pAsc,
 168         HANDLE_FDK_BITSTREAM  hBs,
 169         const INT             ignoreBufferFullness
 170         )
 171 {
 172   INT crcReg;
 173
 174   INT valBits;
 175   INT cmp_buffer_fullness;
 176   int i, adtsHeaderLength;
 177
 178   STRUCT_ADTS_BS bs;
 179
 180 #ifdef TP_PCE_ENABLE
 181   CProgramConfig oldPce;
 182   /* Store the old PCE temporarily. Maybe we'll need it later if we
 183      have channelConfig=0 and no PCE in this frame. */
 184   FDKmemcpy(&oldPce, &pAsc->m_progrConfigElement, sizeof(CProgramConfig));
 185 #endif
 186
 187   valBits = FDKgetValidBits(hBs);
 188
 189   /* adts_fixed_header */
 190   bs.mpeg_id           = FDKreadBits(hBs, Adts_Length_Id);
 191   bs.layer             = FDKreadBits(hBs, Adts_Length_Layer);
 192   bs.protection_absent = FDKreadBits(hBs, Adts_Length_ProtectionAbsent);
 193   bs.profile           = FDKreadBits(hBs, Adts_Length_Profile);
 194   bs.sample_freq_index = FDKreadBits(hBs, Adts_Length_SamplingFrequencyIndex);
 195   bs.private_bit       = FDKreadBits(hBs, Adts_Length_PrivateBit);
 196   bs.channel_config    = FDKreadBits(hBs, Adts_Length_ChannelConfiguration);
 197   bs.original          = FDKreadBits(hBs, Adts_Length_OriginalCopy);
 198   bs.home              = FDKreadBits(hBs, Adts_Length_Home);
 199
 200   /* adts_variable_header */
 201   bs.copyright_id    = FDKreadBits(hBs, Adts_Length_CopyrightIdentificationBit);
 202   bs.copyright_start = FDKreadBits(hBs, Adts_Length_CopyrightIdentificationStart);
 203   bs.frame_length    = FDKreadBits(hBs, Adts_Length_FrameLength);
 204   bs.adts_fullness   = FDKreadBits(hBs, Adts_Length_BufferFullness);
 205   bs.num_raw_blocks  = FDKreadBits(hBs, Adts_Length_NumberOfRawDataBlocksInFrame);
 206   bs.num_pce_bits    = 0;
 207
 208   adtsHeaderLength = ADTS_HEADERLENGTH;
 209
 210   if (!bs.protection_absent) {
 211     FDKcrcReset(&pAdts->crcInfo);
 212     FDKpushBack(hBs, 56);   /* complete fixed and variable header! */
 213     crcReg = FDKcrcStartReg(&pAdts->crcInfo, hBs, 0);
 214     FDKpushFor(hBs, 56);
 215   }
 216
 217   if (! bs.protection_absent && bs.num_raw_blocks>0) {
 218     for (i=0; i<bs.num_raw_blocks; i++) {
 219       pAdts->rawDataBlockDist[i] = (USHORT)FDKreadBits(hBs, 16);
 220       adtsHeaderLength += 16;
 221     }
 222     /* Change raw data blocks to delta values */
 223     pAdts->rawDataBlockDist[bs.num_raw_blocks] = bs.frame_length - 7 - bs.num_raw_blocks*2 - 2 ;
 224     for (i=bs.num_raw_blocks; i>0; i--) {
 225       pAdts->rawDataBlockDist[i] -= pAdts->rawDataBlockDist[i-1];
 226     }
 227   }
 228
 229   /* adts_error_check */
 230   if (!bs.protection_absent)
 231   {
 232     USHORT crc_check;
 233
 234     FDKcrcEndReg(&pAdts->crcInfo, hBs, crcReg);
 235     crc_check = FDKreadBits(hBs, Adts_Length_CrcCheck);
 236     adtsHeaderLength += Adts_Length_CrcCheck;
 237
 238     pAdts->crcReadValue = crc_check;
 239     /* Check header CRC in case of multiple raw data blocks */
 240     if (bs.num_raw_blocks > 0) {
 241       if (pAdts->crcReadValue != FDKcrcGetCRC(&pAdts->crcInfo)) {
 242         return TRANSPORTDEC_CRC_ERROR;
 243       }
 244       /* Reset CRC for the upcoming raw_data_block() */
 245       FDKcrcReset(&pAdts->crcInfo);
 246     }
 247   }
 248
 249
 250   /* check if valid header */
 251   if (
 252       (bs.layer != 0) ||                          // we only support MPEG ADTS
 253       (bs.sample_freq_index >= 13)                // we only support 96kHz - 7350kHz
 254       ) {
 255     FDKpushFor(hBs, bs.frame_length * 8);   // try again one frame later
 256     return TRANSPORTDEC_UNSUPPORTED_FORMAT;
 257   }
 258
 259   /* special treatment of id-bit */
 260   if ( (bs.mpeg_id == 0) && (pAdts->decoderCanDoMpeg4 == 0) )
 261   {
 262     /* MPEG-2 decoder cannot play MPEG-4 bitstreams */
 263
 264
 265     FDKpushFor(hBs, bs.frame_length * 8);  // try again one frame later
 266     return TRANSPORTDEC_UNSUPPORTED_FORMAT;
 267   }
 268
 269   if (!ignoreBufferFullness)
 270   {
 271     cmp_buffer_fullness = bs.frame_length*8 + bs.adts_fullness*32*getNumberOfEffectiveChannels(bs.channel_config);
 272
 273
 274     /* Evaluate buffer fullness */
 275     if (bs.adts_fullness != 0x7FF)
 276     {
 277       if (pAdts->BufferFullnesStartFlag)
 278       {
 279         if ( valBits < cmp_buffer_fullness )
 280         {
 281           /* Condition for start of decoding is not fulfilled */
 282
 283           /* The current frame will not be decoded */
 284           FDKpushBack(hBs, adtsHeaderLength);
 285
 286           if ( (cmp_buffer_fullness+adtsHeaderLength) > ((TRANSPORTDEC_INBUF_SIZE<<3)-7) ) {
 287             return TRANSPORTDEC_SYNC_ERROR;
 288           } else {
 289             return TRANSPORTDEC_NOT_ENOUGH_BITS;
 290           }
 291         }
 292         else
 293         {
 294           pAdts->BufferFullnesStartFlag = 0;
 295         }
 296       }
 297     }
 298   }
 299
 300
 301   /* Get info from ADTS header */
 302   AudioSpecificConfig_Init(pAsc);
 303   pAsc->m_aot                    = (AUDIO_OBJECT_TYPE)(bs.profile + 1);
 304   pAsc->m_samplingFrequencyIndex = bs.sample_freq_index;
 305   pAsc->m_samplingFrequency      = SamplingRateTable[bs.sample_freq_index];
 306   pAsc->m_channelConfiguration   = bs.channel_config;
 307   pAsc->m_samplesPerFrame        = 1024;
 308
 309 #ifdef TP_PCE_ENABLE
 310   if (bs.channel_config == 0)
 311   {
 312     int pceBits = 0;
 313     UINT alignAnchor = FDKgetValidBits(hBs);
 314
 315     if (FDKreadBits(hBs,3) == ID_PCE) {
 316       /* Got luck! Parse the PCE */
 317       int crcReg;
 318       crcReg = adtsRead_CrcStartReg(pAdts, hBs, 0);
 319
 320       CProgramConfig_Read(&pAsc->m_progrConfigElement, hBs, alignAnchor);
 321
 322       adtsRead_CrcEndReg(pAdts, hBs, crcReg);
 323       pceBits = alignAnchor - FDKgetValidBits(hBs);
 324       /* store the number of PCE bits */
 325       bs.num_pce_bits = pceBits;
 326     }
 327     else {
 328       /* No PCE in this frame! Push back the ID tag bits. */
 329       FDKpushBack(hBs,3);
 330
 331       /* Encoders do not have to write a PCE in each frame.
 332          So if we already have a valid PCE we have to use it. */
 333       if (  oldPce.isValid
 334         && (bs.sample_freq_index == pAdts->bs.sample_freq_index)  /* we could compare the complete fixed header (bytes) here! */
 335         && (bs.channel_config    == pAdts->bs.channel_config) /* == 0 */
 336         && (bs.mpeg_id           == pAdts->bs.mpeg_id) )
 337       { /* Restore previous PCE which is still valid */
 338         FDKmemcpy(&pAsc->m_progrConfigElement, &oldPce, sizeof(CProgramConfig));
 339       }
 340       else if (bs.mpeg_id == 0) {
 341         /* If not it seems that we have a implicit channel configuration.
 342            This mode is not allowed in the context of ISO/IEC 14496-3.
 343            Skip this frame and try the next one. */
 344         FDKpushFor(hBs, (bs.frame_length<<3) - adtsHeaderLength - 3);
 345         return TRANSPORTDEC_UNSUPPORTED_FORMAT;
 346       }
 347       /* else {
 348          ISO/IEC 13818-7 implicit channel mapping is allowed.
 349          So just open the box of chocolates to see what we got.
 350       } */
 351     }
 352   }
 353 #endif /* TP_PCE_ENABLE */
 354
 355   /* Copy bit stream data struct to persistent memory now, once we passed all sanity checks above. */
 356   FDKmemcpy(&pAdts->bs, &bs, sizeof(STRUCT_ADTS_BS));
 357
 358   return TRANSPORTDEC_OK;
 359 }
 360
 361 int adtsRead_GetRawDataBlockLength(
 362         HANDLE_ADTS pAdts,
 363         INT         blockNum
 364         )
 365 {
 366   int length;
 367
 368   if (pAdts->bs.num_raw_blocks == 0) {
 369     length = (pAdts->bs.frame_length - 7) << 3;    /* aac_frame_length subtracted by the header size (7 bytes). */
 370     if (pAdts->bs.protection_absent == 0)
 371       length -= 16;                                                                   /* substract 16 bit CRC */
 372   } else {
 373     if (pAdts->bs.protection_absent) {
 374       length = -1; /* raw data block length is unknown */
 375     } else {
 376       if (blockNum < 0 || blockNum > 3) {
 377         length = -1;
 378       }
 379       length = (pAdts->rawDataBlockDist[blockNum] << 3) - 16;
 380     }
 381   }
 382   if (blockNum == 0 && length > 0) {
 383     length -= pAdts->bs.num_pce_bits;
 384   }
 385   return length;
 386 }
 387
 388