1 /* ------------------------------------------------------------------ 2 * Copyright (C) 1998-2009 PacketVideo 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either 13 * express or implied. 14 * See the License for the specific language governing permissions 15 * and limitations under the License. 16 * ------------------------------------------------------------------- 17 */ 18 /* 19 20 Pathname: get_adts_header.c 21 22 ------------------------------------------------------------------------------ 23 REVISION HISTORY 24 25 Description: Remove default_config variable 26 27 Description: change enter_mc_info to set_mc_info 28 29 Description: (1) add error checking for channel_config > 2 30 (2) eliminated call to check_mc_info 31 (3) use (profile + 1) when calling set_mc_info 32 (4) use winmap when calling set_mc_info 33 34 Who: Date: 35 Description: 36 37 ------------------------------------------------------------------------------ 38 INPUT AND OUTPUT DEFINITIONS 39 40 Inputs: 41 pVars = Pointer to structure that holds file-scope variables. 42 [ tDec_Int_File * ] 43 44 pSyncword = Pointer to variable that holds the 28-bit fixed 45 header upon the exit of this function. [ UInt32 * ] 46 47 pInvoke = Pointer to variable that keeps track of how many 48 "short" (14 bit) headers have been successfully 49 parsed from the bitstream. [ Int * ] 50 51 Local Stores/Buffers/Pointers Needed: 52 None 53 54 Global Stores/Buffers/Pointers Needed: 55 None 56 57 Outputs: 58 Status = SUCCESS or ERROR CODE 59 60 Pointers and Buffers Modified: 61 pVars->prog_config Updated with program information data as read from 62 the ADTS header. 63 64 pSyncword Value pointed to is updated with the contents of 65 the 28-bit fixed header. 66 67 pInvoke Value pointed to is updated to reflect the number 68 of successful "short" (14 bit) headers that have 69 been successfully parsed from the bitstream. 70 71 Local Stores Modified: 72 None 73 74 Global Stores Modified: 75 None 76 77 ------------------------------------------------------------------------------ 78 FUNCTION DESCRIPTION 79 80 Acronym Definitions 81 ADTS Audio Data Transport Stream 82 CRC Cyclic Redundancy Code 83 84 This function calls find_adts_syncword to find the next ADTS header. Until 85 three consistent headers have been read, the syncword used for detection 86 consists of the 12-bit syncword and the 2-bit Layer. After three consistent 87 headers are read, the entire fixed header is used for a robust 28-bit 88 syncword. 89 90 Configuration information is then extracted from the bitstream. 91 92 The bitstream information is packed as follows. 93 Comments about the correct interpretation of these bits are contained within 94 the code. 95 96 CRC_absent sampling_rate_idx 97 \ / \ 98 \ / \ 99 \ Profile / \ UNUSED 100 \ / \ / \ / 101 |00|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25| 102 \ _______________ / | \ / \ / 103 \-------|0xFFF syncword |-------/ | Layer == '00' for AAC \ / 104 \-------------/ | \ / 105 | \/ 106 ID == '1' for MPEG-2 AAC channel_config 107 copyright_id_bit == '0' for MPEG-4 AAC 108 / 109 home / 110 / / 111 |26|27|28|29|30|31|32|33|34|35|36|37|38|39|40|41|42| 112 | \ \ _____________ / 113 | \ \--------|frame length |---------/ 114 orig_copy \ \-----------/ 115 \ ______________________________ 116 copyright_id_start | TOTAL HEADER LENGTH: 56 bits| 117 |-----------------------------| 118 |43|44|45|46|47|48|49|50|51|52|53|54|55| | FIXED HEADER BITS 00-27 | 119 \ _______________ / | | | VARIABLE HEADER BITS 28-55 | 120 \-----|buffer_fullness|----/ \ / |_____________________________| 121 \-------------/ | 122 headerless_frames 123 124 In addition to the bits displayed above, if the value CRC_absent is '0' an 125 additional 16 bits corresponding to a CRC word are read from the bitstream, 126 following the header. 127 ------------------------------------------------------------------------------ 128 REQUIREMENTS 129 130 After the ADTS syncword is detected, this function shall parse the 131 information residing behind the syncword in the bitstream. 132 ------------------------------------------------------------------------------ 133 REFERENCES 134 (1) ISO/IEC 13818-7:1997(E) 135 Part 7 136 Subpart 6.2 (Audio_Data_Transport_Stream frame, ADTS) 137 138 (2) ISO/IEC 11172-3:1993(E) 139 Part 3 140 Subpart 2.4.3 The audio decoding process 141 142 (3) MPEG-2 NBC Audio Decoder 143 "This software module was originally developed by AT&T, Dolby 144 Laboratories, Fraunhofer Gesellschaft IIS in the course of development 145 of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and 146 3. This software module is an implementation of a part of one or more 147 MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 148 Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio 149 standards free license to this software module or modifications thereof 150 for use in hardware or software products claiming conformance to the 151 MPEG-2 NBC/MPEG-4 Audio standards. Those UIntending to use this software 152 module in hardware or software products are advised that this use may 153 infringe existing patents. The original developer of this software 154 module and his/her company, the subsequent editors and their companies, 155 and ISO/IEC have no liability for use of this software module or 156 modifications thereof in an implementation. Copyright is not released 157 for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original 158 developer retains full right to use the code for his/her own purpose, 159 assign or donate the code to a third party and to inhibit third party 160 from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products. 161 This copyright notice must be included in all copies or derivative 162 works." 163 Copyright(c)1996. 164 165 ------------------------------------------------------------------------------ 166 PSEUDO-CODE 167 168 IF (*(pInvoke) > 3) 169 170 CALL find_adts_syncword( 171 pSyncword, 172 &(pVars->inputStream), 173 LENGTH_FIXED_HEADER, 174 MASK_28BITS); 175 RETURNING status 176 ELSE 177 178 *(pSyncword) = SYNCWORD_15BITS; 179 180 CALL find_adts_syncword( 181 pSyncword, 182 &(pVars->inputStream), 183 LENGTH_SYNCWORD, 184 ID_BIT_FILTER); 185 186 MODIFYING *(pSyncword) = 28-bit fixed header (long syncword) 187 RETURNING status 188 189 CALL getbits( 190 (LENGTH_FIXED_HEADER - LENGTH_SYNCWORD), 191 &(pVars->inputStream)); 192 193 MODIFYING pVars->inputStream 194 RETURNING adts_header = remaining bits in the fixed header 195 196 *(pSyncword) <<= 13; 197 *(pSyncword) = *(pSyncword) OR adts_header; 198 199 pVars->prog_config.CRC_absent = ((UInt)(adts_header >> 12)) AND 0x0001; 200 201 lower_16 = (UInt)adts_header; 202 203 pVars->prog_config.profile = (lower_16 >> 10) AND 0x3; 204 205 pVars->prog_config.sampling_rate_idx = (lower_16 >> 6) AND 0xF; 206 207 channel_configuration = (lower_16 >> 2) AND 0x7; 208 209 channel_configuration = channel_configuration - 1; 210 pVars->prog_config.front.ele_is_cpe[0] = channel_configuration; 211 212 pVars->prog_config.front.num_ele = 1; 213 214 pVars->prog_config.front.ele_tag[0] = 0; 215 216 pVars->prog_config.mono_mix.present = 0; 217 pVars->prog_config.stereo_mix.present = 0; 218 pVars->prog_config.matrix_mix.present = 0; 219 220 CALL set_mc_info( 221 &(pVars->mc_info), 222 &(pVars->savedMCInfo), 223 &(pVars->prog_config), 224 pVars->pWinSeqInfo, 225 pVars->SFBWidth128); 226 MODIFYING pVars->mc_info = multi-channel configuration information 227 RETURNING status = SUCCESS/FAILURE 228 229 IF ( (*pInvoke) != 0) 230 CALL check_mc_info( 231 &(pVars->mc_info), 232 &(pVars->savedMCInfo), 233 FALSE); 234 RETURNING status = SUCCESS/FAILURE 235 ELSE 236 CALL check_mc_info( 237 &(pVars->mc_info), 238 &(pVars->savedMCInfo), 239 TRUE); 240 MODIFYING pVars->savedMCInfo = pVars->mc_info 241 RETURNING status = SUCCESS/FAILURE 242 ENDIF 243 244 IF (status == SUCCESS) 245 (*pInvoke) = (*pInvoke) + 1; 246 ELSE 247 (*pInvoke) = 0; 248 ENDIF 249 250 ENDIF 251 252 CALL getbits( 253 LENGTH_VARIABLE_HEADER, 254 &(pVars->inputStream)); 255 RETURNING adts_header = 28-bits (the contents of the variable header.) 256 257 pVars->prog_config.frame_length = ((UInt)(adts_header >> 13)) AND 0x1FFF; 258 259 lower_16 = (UInt)adts_header; 260 261 pVars->prog_config.buffer_fullness = (lower_16 >> 2) AND 0x7FF; 262 263 pVars->prog_config.headerless_frames = (lower_16 AND 0x0003); 264 265 IF (pVars->prog_config.CRC_absent == 0) 266 267 CALL getbits( 268 LENGTH_CRC, 269 &(pVars->inputStream) ); 270 RETURNING pVars->prog_config.CRC_check = 16-bit CRC 271 272 ENDIF 273 274 pVars->default_config = 0; 275 276 IF (byte_align_offset > 7) 277 status = 1; 278 ENDIF 279 280 return (status); 281 282 ------------------------------------------------------------------------------ 283 RESOURCES USED 284 When the code is written for a specific target processor the 285 the resources used should be documented below. 286 287 STACK USAGE: [stack count for this module] + [variable to represent 288 stack usage for each subroutine called] 289 290 where: [stack usage variable] = stack usage for [subroutine 291 name] (see [filename].ext) 292 293 DATA MEMORY USED: x words 294 295 PROGRAM MEMORY USED: x words 296 297 CLOCK CYCLES: [cycle count equation for this module] + [variable 298 used to represent cycle count for each subroutine 299 called] 300 301 where: [cycle count variable] = cycle count for [subroutine 302 name] (see [filename].ext) 303 304 ------------------------------------------------------------------------------ 305 */ 306 307 308 /*---------------------------------------------------------------------------- 309 ; INCLUDES 310 ----------------------------------------------------------------------------*/ 311 #include "pv_audio_type_defs.h" 312 #include "s_bits.h" 313 #include "s_tdec_int_file.h" 314 #include "ibstream.h" 315 #include "set_mc_info.h" 316 #include "find_adts_syncword.h" 317 #include "get_adts_header.h" 318 319 /*---------------------------------------------------------------------------- 320 ; MACROS 321 ; Define module specific macros here 322 ----------------------------------------------------------------------------*/ 323 324 /*---------------------------------------------------------------------------- 325 ; DEFINES 326 ; Include all pre-processor statements here. Include conditional 327 ; compile variables also. 328 ----------------------------------------------------------------------------*/ 329 #define LENGTH_VARIABLE_HEADER 28 330 #define LENGTH_FIXED_HEADER 28 331 #define LENGTH_SYNCWORD 15 332 #define LENGTH_CRC 16 333 334 #define ID_BIT_FILTER 0x7FFB 335 #define SYNCWORD_15BITS 0x7FF8 336 #define MASK_28BITS 0x0FFFFFFFL 337 338 /*---------------------------------------------------------------------------- 339 ; LOCAL FUNCTION DEFINITIONS 340 ; Function Prototype declaration 341 ----------------------------------------------------------------------------*/ 342 343 /*---------------------------------------------------------------------------- 344 ; LOCAL STORE/BUFFER/POINTER DEFINITIONS 345 ; Variable declaration - defined here and used outside this module 346 ----------------------------------------------------------------------------*/ 347 348 /*---------------------------------------------------------------------------- 349 ; EXTERNAL FUNCTION REFERENCES 350 ; Declare functions defined elsewhere and referenced in this module 351 ----------------------------------------------------------------------------*/ 352 353 /*---------------------------------------------------------------------------- 354 ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES 355 ; Declare variables used in this module but defined elsewhere 356 ----------------------------------------------------------------------------*/ 357 358 /*---------------------------------------------------------------------------- 359 ; FUNCTION CODE 360 ----------------------------------------------------------------------------*/ 361 Int get_adts_header( 362 tDec_Int_File *pVars, 363 UInt32 *pSyncword, 364 Int *pInvoke, 365 Int CorrectlyReadFramesCount) 366 { 367 UInt32 adts_header; 368 UInt lower_16; 369 Int status = SUCCESS; 370 UInt channel_configuration; 371 372 /* 373 * Search for the LONG ADTS syncword (comprised of the entire fixed header) 374 * if the number of CorrectlyReadFrames is > CorrectlyReadFramesCount 375 * 376 * Otherwise, search for just the short syncword. 377 */ 378 if (*(pInvoke) > CorrectlyReadFramesCount) 379 { 380 /* 381 * Find the long ADTS syncword 382 * (comprised of the entire ADTS fixed header) 383 */ 384 385 status = find_adts_syncword(pSyncword, 386 &(pVars->inputStream), 387 LENGTH_FIXED_HEADER, 388 MASK_28BITS); 389 } 390 else 391 { 392 393 *(pSyncword) = SYNCWORD_15BITS; 394 395 status = find_adts_syncword(pSyncword, 396 &(pVars->inputStream), 397 LENGTH_SYNCWORD, 398 ID_BIT_FILTER); 399 400 /* 401 * Extract the data from the header following the syncword 402 */ 403 adts_header = getbits((LENGTH_FIXED_HEADER - LENGTH_SYNCWORD), 404 &(pVars->inputStream)); 405 406 *(pSyncword) <<= (LENGTH_FIXED_HEADER - LENGTH_SYNCWORD); 407 *(pSyncword) |= adts_header; 408 409 /* Denotes whether a CRC check should be performed */ 410 pVars->prog_config.CRC_absent = ((UInt)(adts_header >> 12)) & 0x0001; 411 412 /* 413 * All the unread bits in adts_header reside in the lower 414 * 16-bits at this point. Perform a typecast for faster 415 * execution on 16-bit processors. 416 */ 417 lower_16 = (UInt)adts_header; 418 419 /* 420 * Profile consists of 2 bits, which indicate 421 * the profile used. 422 * 423 * '00' AAC_MAIN profile 424 * '01' AAC_LC (Low Complexity) profile 425 * '10' AAC_SSR (Scaleable Sampling Rate) profile 426 * '11' AAC_LTP (Long Term Prediction) profile 427 */ 428 pVars->prog_config.profile = (lower_16 >> 10) & 0x3; 429 430 if (pVars->prog_config.profile == MP4AUDIO_AAC_SSR) 431 { 432 status = 1; /* Not supported */ 433 } 434 435 /* 436 * Sampling_rate_idx consists of 4 bits 437 * see Ref #1 for their interpretation. 438 */ 439 pVars->prog_config.sampling_rate_idx = (lower_16 >> 6) & 0xF; 440 441 /* 442 * private_bit is a bit for private use. ISO/IEC will not make 443 * use of this bit in the future. 444 * 445 * We currently make no use of it, but parsing the information 446 * from the bitstream could be easily implemented with the 447 * following instruction... 448 * 449 * private_bit = (lower_16 & 0x0400) >> 10; 450 */ 451 452 /* 453 * These 3 bits indicate the channel configuration used. 454 * 455 * If '0' then the channel configuration is unspecified here, 456 * and must be given by a program configuration element in 457 * the raw data block. 458 * 459 * If '1' then the channel configuration is MONO. 460 * If '2' then the channel configuration is STEREO 461 * 462 * 3-7 represent channel configurations which this library 463 * will not support in the forseeable future. 464 */ 465 channel_configuration = (lower_16 >> 2) & 0x7; 466 /* do not support more than 2 channels */ 467 if (channel_configuration > 2) 468 { 469 status = 1; 470 } 471 472 /* 473 * The following 2 bits encode copyright information. 474 * original_copy is '0' if there is no copyright in the bitstream. 475 * '1' if the bitstream is copyright protected. 476 * 477 * home is '0' for a copy, '1' for an original. 478 * 479 * PacketVideo currently does nothing with this information, 480 * however, parsing the data from the bitstream could be easily 481 * implemented with the following instructions... 482 * 483 * original_copy = (lower_16 >> 1) & 0x1; 484 * 485 * home = (lower_16 & 0x1); 486 * 487 */ 488 489 /* Set up based on information extracted from the ADTS FIXED header */ 490 491 /* This equals 1 for STEREO, 0 for MONO */ 492 if (channel_configuration) 493 { 494 channel_configuration--; 495 } 496 pVars->prog_config.front.ele_is_cpe[0] = channel_configuration; 497 498 /* This value is constant for both MONO and STEREO */ 499 pVars->prog_config.front.num_ele = 1; 500 501 /* ADTS does not specify this tag value - do we even use it? */ 502 pVars->prog_config.front.ele_tag[0] = 0; 503 504 /* Disable all mix related variables */ 505 pVars->prog_config.mono_mix.present = 0; 506 pVars->prog_config.stereo_mix.present = 0; 507 pVars->prog_config.matrix_mix.present = 0; 508 509 /* enter configuration into MC_Info structure */ 510 if (status == SUCCESS) 511 { 512 /* profile + 1 == audioObjectType */ 513 status = 514 set_mc_info( 515 &(pVars->mc_info), 516 (tMP4AudioObjectType)(pVars->prog_config.profile + 1), 517 pVars->prog_config.sampling_rate_idx, 518 pVars->prog_config.front.ele_tag[0], 519 pVars->prog_config.front.ele_is_cpe[0], 520 pVars->winmap, /* changed from pVars->pWinSeqInfo, */ 521 pVars->SFBWidth128); 522 523 } /* if (status == SUCCESS) */ 524 525 526 #ifdef AAC_PLUS 527 528 /* 529 * For implicit signalling, no hint that sbr or ps is used, so we need to 530 * check the sampling frequency of the aac content, if lesser or equal to 531 * 24 KHz, by defualt upsample, otherwise, do nothing 532 */ 533 if ((pVars->prog_config.sampling_rate_idx >= 6) && (pVars->aacPlusEnabled == TRUE)) 534 { 535 pVars->mc_info.upsamplingFactor = 2; 536 pVars->prog_config.sampling_rate_idx -= 3; 537 pVars->mc_info.sbrPresentFlag = 1; 538 pVars->sbrDecoderData.SbrChannel[0].syncState = SBR_ACTIVE; 539 pVars->sbrDecoderData.SbrChannel[1].syncState = SBR_ACTIVE; 540 } 541 #endif 542 543 544 /* 545 * The tag and is_cpe will be checked in huffdecode, 546 * remove this check routine. 547 */ 548 /*if (status == SUCCESS) 549 *{ 550 * if ( (*pInvoke) != 0) 551 * { 552 * status = 553 * check_mc_info( 554 * &(pVars->mc_info), 555 * &(pVars->savedMCInfo), 556 * FALSE); 557 * } 558 * else 559 * { 560 * status = 561 * check_mc_info( 562 * &(pVars->mc_info), 563 * &(pVars->savedMCInfo), 564 * TRUE); 565 * } 566 * 567 *}*/ /* if (status == SUCCESS) */ 568 569 /* 570 * This keeps track of how many headers have been read in the file. 571 * After the three successful headers with the same configuration 572 * are read in, the entire ADTS fixed header is used as the syncword 573 * for a more robust 28-bit long syncword 574 */ 575 576 if (status == SUCCESS) 577 { 578 (*pInvoke)++; 579 } 580 else 581 { 582 (*pInvoke) = 0; 583 } 584 585 } /* END if (*(pInvoke) > 3) */ 586 587 /* Grab the bits in the ADTS variable header */ 588 adts_header = getbits( 589 LENGTH_VARIABLE_HEADER, 590 &(pVars->inputStream)); 591 /* 592 * copyright_identification bit is a single bit of the 72-bit 593 * copyright_id field. This consists of a 8-bit copyright identifier 594 * and a 64-bit copyright_number. 72 headers must be decoded 595 * to reconstruct the entire copyright_id field. 596 * 597 * copyright_identification_start is a single bit flagging 598 * the beginning bit of the copyright_id field. '1' for start of 599 * copyright_id, '0' otherwise. 600 * 601 * 602 * PacketVideo currently does nothing with this information, 603 * however, parsing the data from the bitstream could be easily 604 * implemented with the following instructions... 605 * 606 * copyright_id_bit = ((UInt)(adts_header >> 27)) & 0x1; 607 * 608 * copyright_id_start = ((UInt)(adts_header >> 26)) & 0x1; 609 */ 610 611 /* 612 * frame_length is a 13-bit field which indicates the length, 613 * in bytes, of the frame including error_check and headers. 614 * This information can theoretically be used to help verify syncwords. 615 */ 616 pVars->prog_config.frame_length = ((UInt)(adts_header >> 13)) & 0x1FFF; 617 618 /* 619 * All the unread bits in adts_header reside in the lower 620 * 16-bits at this point. Perform a typecast for faster 621 * execution on 16-bit processors. 622 */ 623 lower_16 = (UInt)adts_header; 624 625 /* 626 * Indicates the number of 32-bit words remaining in the 627 * encoder buffer after the encoding of the first raw 628 * data block. This value is 0x7ff for variable bit 629 * rate encoders, since buffer fullness does not apply 630 * to Variable Bit Rate (VBR) encoders. 631 */ 632 pVars->prog_config.buffer_fullness = (lower_16 >> 2) & 0x7FF; 633 634 /* 635 * headerless_frames indicates the number of 636 * frames with no headers to be processed before the reading 637 * in of the next header. 638 * 639 * In ADTS, up to 4 "no header frames" can exist between 640 * syncwords. 641 * 642 * EXAMPLES: 643 * 644 * Legend: (Sync words denoted by X, frames 645 * deonted by FRAME_#) 646 * 647 * Example(1): The ADTS sequence below packs 5 648 * frames per header. 649 * Here, headerless_frames would always be read in as "4" 650 * 651 * |X||FRAME_0||FRAME_1||FRAME_2||FRAME_3||FRAME_4||X||FRAME_0| 652 * 653 * Example(2): The ADTS sequence below packs 1 frame per header. 654 * Here, headerless_frames would always be read in as "0" 655 * 656 * |X||FRAME_0||X||FRAME_1||X||FRAME_2| 657 * 658 */ 659 pVars->prog_config.headerless_frames = (lower_16 & 0x0003); 660 661 if (pVars->prog_config.CRC_absent == 0) 662 { 663 pVars->prog_config.CRC_check = (UInt)getbits( 664 LENGTH_CRC, 665 &(pVars->inputStream)); 666 } 667 668 /* pVars->current_program = 0; */ /* shall be set after PCE is read */ 669 670 return (status); 671 672 } /* END get_adts_header */ 673
