diff options
Diffstat (limited to 'media/libstagefright/codecs/aacdec/get_adts_header.cpp')
| -rw-r--r-- | media/libstagefright/codecs/aacdec/get_adts_header.cpp | 672 |
1 files changed, 672 insertions, 0 deletions
diff --git a/media/libstagefright/codecs/aacdec/get_adts_header.cpp b/media/libstagefright/codecs/aacdec/get_adts_header.cpp new file mode 100644 index 0000000..3ac2756 --- /dev/null +++ b/media/libstagefright/codecs/aacdec/get_adts_header.cpp @@ -0,0 +1,672 @@ +/* ------------------------------------------------------------------ + * Copyright (C) 1998-2009 PacketVideo + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either + * express or implied. + * See the License for the specific language governing permissions + * and limitations under the License. + * ------------------------------------------------------------------- + */ +/* + + Pathname: get_adts_header.c + +------------------------------------------------------------------------------ + REVISION HISTORY + + Description: Remove default_config variable + + Description: change enter_mc_info to set_mc_info + + Description: (1) add error checking for channel_config > 2 + (2) eliminated call to check_mc_info + (3) use (profile + 1) when calling set_mc_info + (4) use winmap when calling set_mc_info + + Who: Date: + Description: + +------------------------------------------------------------------------------ + INPUT AND OUTPUT DEFINITIONS + + Inputs: + pVars = Pointer to structure that holds file-scope variables. + [ tDec_Int_File * ] + + pSyncword = Pointer to variable that holds the 28-bit fixed + header upon the exit of this function. [ UInt32 * ] + + pInvoke = Pointer to variable that keeps track of how many + "short" (14 bit) headers have been successfully + parsed from the bitstream. [ Int * ] + + Local Stores/Buffers/Pointers Needed: + None + + Global Stores/Buffers/Pointers Needed: + None + + Outputs: + Status = SUCCESS or ERROR CODE + + Pointers and Buffers Modified: + pVars->prog_config Updated with program information data as read from + the ADTS header. + + pSyncword Value pointed to is updated with the contents of + the 28-bit fixed header. + + pInvoke Value pointed to is updated to reflect the number + of successful "short" (14 bit) headers that have + been successfully parsed from the bitstream. + + Local Stores Modified: + None + + Global Stores Modified: + None + +------------------------------------------------------------------------------ + FUNCTION DESCRIPTION + + Acronym Definitions + ADTS Audio Data Transport Stream + CRC Cyclic Redundancy Code + + This function calls find_adts_syncword to find the next ADTS header. Until + three consistent headers have been read, the syncword used for detection + consists of the 12-bit syncword and the 2-bit Layer. After three consistent + headers are read, the entire fixed header is used for a robust 28-bit + syncword. + + Configuration information is then extracted from the bitstream. + + The bitstream information is packed as follows. + Comments about the correct interpretation of these bits are contained within + the code. + + CRC_absent sampling_rate_idx + \ / \ + \ / \ + \ Profile / \ UNUSED + \ / \ / \ / +|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| + \ _______________ / | \ / \ / + \-------|0xFFF syncword |-------/ | Layer == '00' for AAC \ / + \-------------/ | \ / + | \/ + ID == '1' for MPEG-2 AAC channel_config + copyright_id_bit == '0' for MPEG-4 AAC + / + home / + / / +|26|27|28|29|30|31|32|33|34|35|36|37|38|39|40|41|42| + | \ \ _____________ / + | \ \--------|frame length |---------/ + orig_copy \ \-----------/ + \ ______________________________ + copyright_id_start | TOTAL HEADER LENGTH: 56 bits| + |-----------------------------| +|43|44|45|46|47|48|49|50|51|52|53|54|55| | FIXED HEADER BITS 00-27 | + \ _______________ / | | | VARIABLE HEADER BITS 28-55 | + \-----|buffer_fullness|----/ \ / |_____________________________| + \-------------/ | + headerless_frames + + In addition to the bits displayed above, if the value CRC_absent is '0' an + additional 16 bits corresponding to a CRC word are read from the bitstream, + following the header. +------------------------------------------------------------------------------ + REQUIREMENTS + + After the ADTS syncword is detected, this function shall parse the + information residing behind the syncword in the bitstream. +------------------------------------------------------------------------------ + REFERENCES + (1) ISO/IEC 13818-7:1997(E) + Part 7 + Subpart 6.2 (Audio_Data_Transport_Stream frame, ADTS) + + (2) ISO/IEC 11172-3:1993(E) + Part 3 + Subpart 2.4.3 The audio decoding process + + (3) MPEG-2 NBC Audio Decoder + "This software module was originally developed by AT&T, Dolby + Laboratories, Fraunhofer Gesellschaft IIS in the course of development + of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and + 3. This software module is an implementation of a part of one or more + MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4 + Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio + standards free license to this software module or modifications thereof + for use in hardware or software products claiming conformance to the + MPEG-2 NBC/MPEG-4 Audio standards. Those UIntending to use this software + module in hardware or software products are advised that this use may + infringe existing patents. The original developer of this software + module and his/her company, the subsequent editors and their companies, + and ISO/IEC have no liability for use of this software module or + modifications thereof in an implementation. Copyright is not released + for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original + developer retains full right to use the code for his/her own purpose, + assign or donate the code to a third party and to inhibit third party + from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products. + This copyright notice must be included in all copies or derivative + works." + Copyright(c)1996. + +------------------------------------------------------------------------------ + PSEUDO-CODE + + IF (*(pInvoke) > 3) + + CALL find_adts_syncword( + pSyncword, + &(pVars->inputStream), + LENGTH_FIXED_HEADER, + MASK_28BITS); + RETURNING status + ELSE + + *(pSyncword) = SYNCWORD_15BITS; + + CALL find_adts_syncword( + pSyncword, + &(pVars->inputStream), + LENGTH_SYNCWORD, + ID_BIT_FILTER); + + MODIFYING *(pSyncword) = 28-bit fixed header (long syncword) + RETURNING status + + CALL getbits( + (LENGTH_FIXED_HEADER - LENGTH_SYNCWORD), + &(pVars->inputStream)); + + MODIFYING pVars->inputStream + RETURNING adts_header = remaining bits in the fixed header + + *(pSyncword) <<= 13; + *(pSyncword) = *(pSyncword) OR adts_header; + + pVars->prog_config.CRC_absent = ((UInt)(adts_header >> 12)) AND 0x0001; + + lower_16 = (UInt)adts_header; + + pVars->prog_config.profile = (lower_16 >> 10) AND 0x3; + + pVars->prog_config.sampling_rate_idx = (lower_16 >> 6) AND 0xF; + + channel_configuration = (lower_16 >> 2) AND 0x7; + + channel_configuration = channel_configuration - 1; + pVars->prog_config.front.ele_is_cpe[0] = channel_configuration; + + pVars->prog_config.front.num_ele = 1; + + pVars->prog_config.front.ele_tag[0] = 0; + + pVars->prog_config.mono_mix.present = 0; + pVars->prog_config.stereo_mix.present = 0; + pVars->prog_config.matrix_mix.present = 0; + + CALL set_mc_info( + &(pVars->mc_info), + &(pVars->savedMCInfo), + &(pVars->prog_config), + pVars->pWinSeqInfo, + pVars->SFBWidth128); + MODIFYING pVars->mc_info = multi-channel configuration information + RETURNING status = SUCCESS/FAILURE + + IF ( (*pInvoke) != 0) + CALL check_mc_info( + &(pVars->mc_info), + &(pVars->savedMCInfo), + FALSE); + RETURNING status = SUCCESS/FAILURE + ELSE + CALL check_mc_info( + &(pVars->mc_info), + &(pVars->savedMCInfo), + TRUE); + MODIFYING pVars->savedMCInfo = pVars->mc_info + RETURNING status = SUCCESS/FAILURE + ENDIF + + IF (status == SUCCESS) + (*pInvoke) = (*pInvoke) + 1; + ELSE + (*pInvoke) = 0; + ENDIF + + ENDIF + + CALL getbits( + LENGTH_VARIABLE_HEADER, + &(pVars->inputStream)); + RETURNING adts_header = 28-bits (the contents of the variable header.) + + pVars->prog_config.frame_length = ((UInt)(adts_header >> 13)) AND 0x1FFF; + + lower_16 = (UInt)adts_header; + + pVars->prog_config.buffer_fullness = (lower_16 >> 2) AND 0x7FF; + + pVars->prog_config.headerless_frames = (lower_16 AND 0x0003); + + IF (pVars->prog_config.CRC_absent == 0) + + CALL getbits( + LENGTH_CRC, + &(pVars->inputStream) ); + RETURNING pVars->prog_config.CRC_check = 16-bit CRC + + ENDIF + + pVars->default_config = 0; + + IF (byte_align_offset > 7) + status = 1; + ENDIF + + return (status); + +------------------------------------------------------------------------------ + RESOURCES USED + When the code is written for a specific target processor the + the resources used should be documented below. + + STACK USAGE: [stack count for this module] + [variable to represent + stack usage for each subroutine called] + + where: [stack usage variable] = stack usage for [subroutine + name] (see [filename].ext) + + DATA MEMORY USED: x words + + PROGRAM MEMORY USED: x words + + CLOCK CYCLES: [cycle count equation for this module] + [variable + used to represent cycle count for each subroutine + called] + + where: [cycle count variable] = cycle count for [subroutine + name] (see [filename].ext) + +------------------------------------------------------------------------------ +*/ + + +/*---------------------------------------------------------------------------- +; INCLUDES +----------------------------------------------------------------------------*/ +#include "pv_audio_type_defs.h" +#include "s_bits.h" +#include "s_tdec_int_file.h" +#include "ibstream.h" +#include "set_mc_info.h" +#include "find_adts_syncword.h" +#include "get_adts_header.h" + +/*---------------------------------------------------------------------------- +; MACROS +; Define module specific macros here +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; DEFINES +; Include all pre-processor statements here. Include conditional +; compile variables also. +----------------------------------------------------------------------------*/ +#define LENGTH_VARIABLE_HEADER 28 +#define LENGTH_FIXED_HEADER 28 +#define LENGTH_SYNCWORD 15 +#define LENGTH_CRC 16 + +#define ID_BIT_FILTER 0x7FFB +#define SYNCWORD_15BITS 0x7FF8 +#define MASK_28BITS 0x0FFFFFFFL + +/*---------------------------------------------------------------------------- +; LOCAL FUNCTION DEFINITIONS +; Function Prototype declaration +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; LOCAL STORE/BUFFER/POINTER DEFINITIONS +; Variable declaration - defined here and used outside this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL FUNCTION REFERENCES +; Declare functions defined elsewhere and referenced in this module +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES +; Declare variables used in this module but defined elsewhere +----------------------------------------------------------------------------*/ + +/*---------------------------------------------------------------------------- +; FUNCTION CODE +----------------------------------------------------------------------------*/ +Int get_adts_header( + tDec_Int_File *pVars, + UInt32 *pSyncword, + Int *pInvoke, + Int CorrectlyReadFramesCount) +{ + UInt32 adts_header; + UInt lower_16; + Int status = SUCCESS; + UInt channel_configuration; + + /* + * Search for the LONG ADTS syncword (comprised of the entire fixed header) + * if the number of CorrectlyReadFrames is > CorrectlyReadFramesCount + * + * Otherwise, search for just the short syncword. + */ + if (*(pInvoke) > CorrectlyReadFramesCount) + { + /* + * Find the long ADTS syncword + * (comprised of the entire ADTS fixed header) + */ + + status = find_adts_syncword(pSyncword, + &(pVars->inputStream), + LENGTH_FIXED_HEADER, + MASK_28BITS); + } + else + { + + *(pSyncword) = SYNCWORD_15BITS; + + status = find_adts_syncword(pSyncword, + &(pVars->inputStream), + LENGTH_SYNCWORD, + ID_BIT_FILTER); + + /* + * Extract the data from the header following the syncword + */ + adts_header = getbits((LENGTH_FIXED_HEADER - LENGTH_SYNCWORD), + &(pVars->inputStream)); + + *(pSyncword) <<= (LENGTH_FIXED_HEADER - LENGTH_SYNCWORD); + *(pSyncword) |= adts_header; + + /* Denotes whether a CRC check should be performed */ + pVars->prog_config.CRC_absent = ((UInt)(adts_header >> 12)) & 0x0001; + + /* + * All the unread bits in adts_header reside in the lower + * 16-bits at this point. Perform a typecast for faster + * execution on 16-bit processors. + */ + lower_16 = (UInt)adts_header; + + /* + * Profile consists of 2 bits, which indicate + * the profile used. + * + * '00' AAC_MAIN profile + * '01' AAC_LC (Low Complexity) profile + * '10' AAC_SSR (Scaleable Sampling Rate) profile + * '11' AAC_LTP (Long Term Prediction) profile + */ + pVars->prog_config.profile = (lower_16 >> 10) & 0x3; + + if (pVars->prog_config.profile == MP4AUDIO_AAC_SSR) + { + status = 1; /* Not supported */ + } + + /* + * Sampling_rate_idx consists of 4 bits + * see Ref #1 for their interpretation. + */ + pVars->prog_config.sampling_rate_idx = (lower_16 >> 6) & 0xF; + + /* + * private_bit is a bit for private use. ISO/IEC will not make + * use of this bit in the future. + * + * We currently make no use of it, but parsing the information + * from the bitstream could be easily implemented with the + * following instruction... + * + * private_bit = (lower_16 & 0x0400) >> 10; + */ + + /* + * These 3 bits indicate the channel configuration used. + * + * If '0' then the channel configuration is unspecified here, + * and must be given by a program configuration element in + * the raw data block. + * + * If '1' then the channel configuration is MONO. + * If '2' then the channel configuration is STEREO + * + * 3-7 represent channel configurations which this library + * will not support in the forseeable future. + */ + channel_configuration = (lower_16 >> 2) & 0x7; + /* do not support more than 2 channels */ + if (channel_configuration > 2) + { + status = 1; + } + + /* + * The following 2 bits encode copyright information. + * original_copy is '0' if there is no copyright in the bitstream. + * '1' if the bitstream is copyright protected. + * + * home is '0' for a copy, '1' for an original. + * + * PacketVideo currently does nothing with this information, + * however, parsing the data from the bitstream could be easily + * implemented with the following instructions... + * + * original_copy = (lower_16 >> 1) & 0x1; + * + * home = (lower_16 & 0x1); + * + */ + + /* Set up based on information extracted from the ADTS FIXED header */ + + /* This equals 1 for STEREO, 0 for MONO */ + if (channel_configuration) + { + channel_configuration--; + } + pVars->prog_config.front.ele_is_cpe[0] = channel_configuration; + + /* This value is constant for both MONO and STEREO */ + pVars->prog_config.front.num_ele = 1; + + /* ADTS does not specify this tag value - do we even use it? */ + pVars->prog_config.front.ele_tag[0] = 0; + + /* Disable all mix related variables */ + pVars->prog_config.mono_mix.present = 0; + pVars->prog_config.stereo_mix.present = 0; + pVars->prog_config.matrix_mix.present = 0; + + /* enter configuration into MC_Info structure */ + if (status == SUCCESS) + { + /* profile + 1 == audioObjectType */ + status = + set_mc_info( + &(pVars->mc_info), + (tMP4AudioObjectType)(pVars->prog_config.profile + 1), + pVars->prog_config.sampling_rate_idx, + pVars->prog_config.front.ele_tag[0], + pVars->prog_config.front.ele_is_cpe[0], + pVars->winmap, /* changed from pVars->pWinSeqInfo, */ + pVars->SFBWidth128); + + } /* if (status == SUCCESS) */ + + +#ifdef AAC_PLUS + + /* + * For implicit signalling, no hint that sbr or ps is used, so we need to + * check the sampling frequency of the aac content, if lesser or equal to + * 24 KHz, by defualt upsample, otherwise, do nothing + */ + if ((pVars->prog_config.sampling_rate_idx >= 6) && (pVars->aacPlusEnabled == TRUE)) + { + pVars->mc_info.upsamplingFactor = 2; + pVars->prog_config.sampling_rate_idx -= 3; + pVars->mc_info.sbrPresentFlag = 1; + pVars->sbrDecoderData.SbrChannel[0].syncState = SBR_ACTIVE; + pVars->sbrDecoderData.SbrChannel[1].syncState = SBR_ACTIVE; + } +#endif + + + /* + * The tag and is_cpe will be checked in huffdecode, + * remove this check routine. + */ + /*if (status == SUCCESS) + *{ + * if ( (*pInvoke) != 0) + * { + * status = + * check_mc_info( + * &(pVars->mc_info), + * &(pVars->savedMCInfo), + * FALSE); + * } + * else + * { + * status = + * check_mc_info( + * &(pVars->mc_info), + * &(pVars->savedMCInfo), + * TRUE); + * } + * + *}*/ /* if (status == SUCCESS) */ + + /* + * This keeps track of how many headers have been read in the file. + * After the three successful headers with the same configuration + * are read in, the entire ADTS fixed header is used as the syncword + * for a more robust 28-bit long syncword + */ + + if (status == SUCCESS) + { + (*pInvoke)++; + } + else + { + (*pInvoke) = 0; + } + + } /* END if (*(pInvoke) > 3) */ + + /* Grab the bits in the ADTS variable header */ + adts_header = getbits( + LENGTH_VARIABLE_HEADER, + &(pVars->inputStream)); + /* + * copyright_identification bit is a single bit of the 72-bit + * copyright_id field. This consists of a 8-bit copyright identifier + * and a 64-bit copyright_number. 72 headers must be decoded + * to reconstruct the entire copyright_id field. + * + * copyright_identification_start is a single bit flagging + * the beginning bit of the copyright_id field. '1' for start of + * copyright_id, '0' otherwise. + * + * + * PacketVideo currently does nothing with this information, + * however, parsing the data from the bitstream could be easily + * implemented with the following instructions... + * + * copyright_id_bit = ((UInt)(adts_header >> 27)) & 0x1; + * + * copyright_id_start = ((UInt)(adts_header >> 26)) & 0x1; + */ + + /* + * frame_length is a 13-bit field which indicates the length, + * in bytes, of the frame including error_check and headers. + * This information can theoretically be used to help verify syncwords. + */ + pVars->prog_config.frame_length = ((UInt)(adts_header >> 13)) & 0x1FFF; + + /* + * All the unread bits in adts_header reside in the lower + * 16-bits at this point. Perform a typecast for faster + * execution on 16-bit processors. + */ + lower_16 = (UInt)adts_header; + + /* + * Indicates the number of 32-bit words remaining in the + * encoder buffer after the encoding of the first raw + * data block. This value is 0x7ff for variable bit + * rate encoders, since buffer fullness does not apply + * to Variable Bit Rate (VBR) encoders. + */ + pVars->prog_config.buffer_fullness = (lower_16 >> 2) & 0x7FF; + + /* + * headerless_frames indicates the number of + * frames with no headers to be processed before the reading + * in of the next header. + * + * In ADTS, up to 4 "no header frames" can exist between + * syncwords. + * + * EXAMPLES: + * + * Legend: (Sync words denoted by X, frames + * deonted by FRAME_#) + * + * Example(1): The ADTS sequence below packs 5 + * frames per header. + * Here, headerless_frames would always be read in as "4" + * + * |X||FRAME_0||FRAME_1||FRAME_2||FRAME_3||FRAME_4||X||FRAME_0| + * + * Example(2): The ADTS sequence below packs 1 frame per header. + * Here, headerless_frames would always be read in as "0" + * + * |X||FRAME_0||X||FRAME_1||X||FRAME_2| + * + */ + pVars->prog_config.headerless_frames = (lower_16 & 0x0003); + + if (pVars->prog_config.CRC_absent == 0) + { + pVars->prog_config.CRC_check = (UInt)getbits( + LENGTH_CRC, + &(pVars->inputStream)); + } + + /* pVars->current_program = 0; */ /* shall be set after PCE is read */ + + return (status); + +} /* END get_adts_header */ |