importer/adts_imp.c

   1 /*****************************************************************************
   2  * adts_imp.c
   3  *****************************************************************************
   4  * Copyright (C) 2010-2017 L-SMASH project
   5  *
   6  * Authors: Takashi Hirata <silverfilain@gmail.com>
   7  * Contributors: Yusuke Nakamura <muken.the.vfrmaniac@gmail.com>
   8  *
   9  * Permission to use, copy, modify, and/or distribute this software for any
  10  * purpose with or without fee is hereby granted, provided that the above
  11  * copyright notice and this permission notice appear in all copies.
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  14  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  15  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  16  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  17  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  18  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  19  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  20  *****************************************************************************/
  21
  22 /* This file is available under an ISC license. */
  23
  24 #include "common/internal.h" /* must be placed first */
  25
  26 #define LSMASH_IMPORTER_INTERNAL
  27 #include "importer.h"
  28
  29 /***************************************************************************
  30     ADTS importer
  31 ***************************************************************************/
  32 #include "codecs/mp4a.h"
  33
  34 #define MP4SYS_ADTS_FIXED_HEADER_LENGTH 4 /* this is partly a lie. actually 28 bits. */
  35 #define MP4SYS_ADTS_BASIC_HEADER_LENGTH 7
  36 #define MP4SYS_ADTS_MAX_FRAME_LENGTH (( 1 << 13 ) - 1)
  37 #define MP4SYS_ADTS_MAX_RAW_DATA_BLOCKS 4
  38
  39 typedef struct
  40 {
  41     uint16_t syncword;                           /* 12; */
  42     uint8_t  ID;                                 /*  1; */
  43     uint8_t  layer;                              /*  2; */
  44     uint8_t  protection_absent;                  /*  1; */
  45     uint8_t  profile_ObjectType;                 /*  2; */
  46     uint8_t  sampling_frequency_index;           /*  4; */
  47 //  uint8_t  private_bit;                        /*  1; we don't care. */
  48     uint8_t  channel_configuration;              /*  3; */
  49 //  uint8_t  original_copy;                      /*  1; we don't care. */
  50 //  uint8_t  home;                               /*  1; we don't care. */
  51
  52 } mp4sys_adts_fixed_header_t;
  53
  54 typedef struct
  55 {
  56 //  uint8_t  copyright_identification_bit;       /*  1; we don't care. */
  57 //  uint8_t  copyright_identification_start;     /*  1; we don't care. */
  58     uint16_t frame_length;                       /* 13; */
  59 //  uint16_t adts_buffer_fullness;               /* 11; we don't care. */
  60     uint8_t  number_of_raw_data_blocks_in_frame; /*  2; */
  61 //  uint16_t adts_error_check;                                           /* we don't support */
  62 //  uint16_t raw_data_block_position[MP4SYS_ADTS_MAX_RAW_DATA_BLOCKS-1]; /* we don't use this directly, and... */
  63     uint16_t raw_data_block_size[MP4SYS_ADTS_MAX_RAW_DATA_BLOCKS];       /* use this instead of above. */
  64 //  uint16_t adts_header_error_check;                                    /* we don't support, actually crc_check within this */
  65 //  uint16_t adts_raw_data_block_error_check[MP4SYS_ADTS_MAX_RAW_DATA_BLOCKS]; /* we don't support */
  66 } mp4sys_adts_variable_header_t;
  67
  68 typedef struct
  69 {
  70     unsigned int                  raw_data_block_idx;
  71     mp4sys_adts_fixed_header_t    header;
  72     mp4sys_adts_variable_header_t variable_header;
  73     uint32_t                      samples_in_frame;
  74     uint32_t                      au_number;
  75 } mp4sys_adts_importer_t;
  76
  77 static void remove_mp4sys_adts_importer
  78 (
  79     mp4sys_adts_importer_t *adts_imp
  80 )
  81 {
  82     lsmash_free( adts_imp );
  83 }
  84
  85 static mp4sys_adts_importer_t *create_mp4sys_adts_importer
  86 (
  87     importer_t *importer
  88 )
  89 {
  90     return (mp4sys_adts_importer_t *)lsmash_malloc_zero( sizeof(mp4sys_adts_importer_t) );
  91 }
  92
  93 static void mp4sys_adts_cleanup( importer_t *importer )
  94 {
  95     debug_if( importer && importer->info )
  96         remove_mp4sys_adts_importer( importer->info );
  97 }
  98
  99 static void mp4sys_adts_parse_fixed_header
 100 (
 101     uint8_t                    *buf,
 102     mp4sys_adts_fixed_header_t *header
 103 )
 104 {
 105     /* FIXME: should we rewrite these code using bitstream reader? */
 106     header->syncword                 = (buf[0] << 4) | (buf[1] >> 4);
 107     header->ID                       = (buf[1] >> 3) & 0x1;
 108     header->layer                    = (buf[1] >> 1) & 0x3;
 109     header->protection_absent        = buf[1] & 0x1;
 110     header->profile_ObjectType       = buf[2] >> 6;
 111     header->sampling_frequency_index = (buf[2] >> 2) & 0xF;
 112 //  header->private_bit              = (buf[2] >> 1) & 0x1; /* we don't care currently. */
 113     header->channel_configuration    = ((buf[2] << 2) | (buf[3] >> 6)) & 0x07;
 114 //  header->original_copy            = (buf[3] >> 5) & 0x1; /* we don't care currently. */
 115 //  header->home                     = (buf[3] >> 4) & 0x1; /* we don't care currently. */
 116 }
 117
 118 static int mp4sys_adts_check_fixed_header
 119 (
 120     mp4sys_adts_fixed_header_t *header
 121 )
 122 {
 123     if( header->syncword != 0xFFF )              return LSMASH_ERR_INVALID_DATA;
 124 //  if( header->ID != 0x0 )                      return LSMASH_ERR_NAMELESS;        /* we don't care. */
 125     if( header->layer != 0x0 )                   return LSMASH_ERR_INVALID_DATA;    /* must be 0b00 for any type of AAC */
 126 //  if( header->protection_absent != 0x1 )       return LSMASH_ERR_NAMELESS;        /* we don't care. */
 127     if( header->profile_ObjectType != 0x1 )      return LSMASH_ERR_PATCH_WELCOME;   /* FIXME: 0b00=Main, 0b01=LC, 0b10=SSR, 0b11=LTP. */
 128     if( header->sampling_frequency_index > 0xB ) return LSMASH_ERR_INVALID_DATA;    /* must not be > 0xB. */
 129     if( header->channel_configuration == 0x0 )   return LSMASH_ERR_PATCH_WELCOME;   /* FIXME: we do not support 0b000 currently. */
 130     if( header->profile_ObjectType == 0x3 && header->ID != 0x0 ) return LSMASH_ERR_INVALID_DATA; /* LTP is valid only if ID==0. */
 131     return 0;
 132 }
 133
 134 static int mp4sys_adts_parse_variable_header
 135 (
 136     lsmash_bs_t                   *bs,
 137     uint8_t                       *buf,
 138     unsigned int                   protection_absent,
 139     mp4sys_adts_variable_header_t *header
 140 )
 141 {
 142     /* FIXME: should we rewrite these code using bitstream reader? */
 143 //  header->copyright_identification_bit       = (buf[3] >> 3) & 0x1; /* we don't care. */
 144 //  header->copyright_identification_start     = (buf[3] >> 2) & 0x1; /* we don't care. */
 145     header->frame_length                       = ((buf[3] << 11) | (buf[4] << 3) | (buf[5] >> 5)) & 0x1FFF ;
 146 //  header->adts_buffer_fullness               = ((buf[5] << 6) | (buf[6] >> 2)) 0x7FF ;  /* we don't care. */
 147     header->number_of_raw_data_blocks_in_frame = buf[6] & 0x3;
 148
 149     if( header->frame_length <= MP4SYS_ADTS_BASIC_HEADER_LENGTH + 2 * (protection_absent == 0) )
 150         return LSMASH_ERR_INVALID_DATA; /* easy error check */
 151
 152     /* protection_absent and number_of_raw_data_blocks_in_frame relatives */
 153
 154     uint8_t buf2[2];
 155     unsigned int number_of_blocks = header->number_of_raw_data_blocks_in_frame;
 156     if( number_of_blocks == 0 )
 157     {
 158         header->raw_data_block_size[0] = header->frame_length - MP4SYS_ADTS_BASIC_HEADER_LENGTH;
 159         /* skip adts_error_check() and subtract that from block_size */
 160         if( protection_absent == 0 )
 161         {
 162             header->raw_data_block_size[0] -= 2;
 163             if( lsmash_bs_get_bytes_ex( bs, 2, buf2 ) != 2 )
 164                 return LSMASH_ERR_INVALID_DATA;
 165         }
 166         return 0;
 167     }
 168
 169     /* now we have multiple raw_data_block()s, so evaluate adts_header_error_check() */
 170
 171     uint16_t raw_data_block_position[MP4SYS_ADTS_MAX_RAW_DATA_BLOCKS];
 172     uint16_t first_offset = MP4SYS_ADTS_BASIC_HEADER_LENGTH;
 173     if( protection_absent == 0 )
 174     {
 175         /* process adts_header_error_check() */
 176         for( int i = 0 ; i < number_of_blocks ; i++ ) /* 1-based in the spec, but we use 0-based */
 177         {
 178             if( lsmash_bs_get_bytes_ex( bs, 2, buf2 ) != 2 )
 179                 return LSMASH_ERR_INVALID_DATA;
 180             raw_data_block_position[i] = LSMASH_GET_BE16( buf2 );
 181         }
 182         /* skip crc_check in adts_header_error_check().
 183            Or might be sizeof( adts_error_check() ) if we share with the case number_of_raw_data_blocks_in_frame == 0 */
 184         if( lsmash_bs_get_bytes_ex( bs, 2, buf2 ) != 2 )
 185             return LSMASH_ERR_INVALID_DATA;
 186         first_offset += ( 2 * number_of_blocks ) + 2; /* according to above */
 187     }
 188     else
 189     {
 190         /*
 191          * NOTE: We never support the case where number_of_raw_data_blocks_in_frame != 0 && protection_absent != 0,
 192          * because we have to parse the raw AAC bitstream itself to find boundaries of raw_data_block()s in this case.
 193          * Which is to say, that braindamaged spec requires us (mp4 muxer) to decode AAC once to split frames.
 194          * L-SMASH is NOT AAC DECODER, so that we've just given up for this case.
 195          * This is ISO/IEC 13818-7's sin which defines ADTS format originally.
 196          */
 197         return LSMASH_ERR_NAMELESS;
 198     }
 199
 200     /* convert raw_data_block_position --> raw_data_block_size */
 201
 202     /* do conversion for first */
 203     header->raw_data_block_size[0] = raw_data_block_position[0] - first_offset;
 204     /* set dummy offset to tail for loop, do coversion for rest. */
 205     raw_data_block_position[number_of_blocks] = header->frame_length;
 206     for( int i = 1 ; i <= number_of_blocks ; i++ )
 207         header->raw_data_block_size[i] = raw_data_block_position[i] - raw_data_block_position[i-1];
 208
 209     /* adjustment for adts_raw_data_block_error_check() */
 210     if( protection_absent == 0 && number_of_blocks != 0 )
 211         for( int i = 0 ; i <= number_of_blocks ; i++ )
 212             header->raw_data_block_size[i] -= 2;
 213
 214     return 0;
 215 }
 216
 217 static int mp4sys_adts_parse_headers
 218 (
 219     lsmash_bs_t                   *bs,
 220     uint8_t                       *buf,
 221     mp4sys_adts_fixed_header_t    *header,
 222     mp4sys_adts_variable_header_t *variable_header
 223 )
 224 {
 225     mp4sys_adts_parse_fixed_header( buf, header );
 226     int err = mp4sys_adts_check_fixed_header( header );
 227     if( err < 0 )
 228         return err;
 229     /* get payload length & skip extra(crc) header */
 230     return mp4sys_adts_parse_variable_header( bs, buf, header->protection_absent, variable_header );
 231 }
 232
 233 static lsmash_audio_summary_t *mp4sys_adts_create_summary
 234 (
 235     mp4sys_adts_fixed_header_t *header
 236 )
 237 {
 238     lsmash_audio_summary_t *summary = (lsmash_audio_summary_t *)lsmash_create_summary( LSMASH_SUMMARY_TYPE_AUDIO );
 239     if( !summary )
 240         return NULL;
 241     summary->sample_type            = ISOM_CODEC_TYPE_MP4A_AUDIO;
 242     summary->max_au_length          = MP4SYS_ADTS_MAX_FRAME_LENGTH;
 243     summary->frequency              = mp4a_sampling_frequency_table[header->sampling_frequency_index][1];
 244     summary->channels               = header->channel_configuration + ( header->channel_configuration == 0x07 ); /* 0x07 means 7.1ch */
 245     summary->sample_size            = 16;
 246     summary->samples_in_frame       = 1024;
 247     summary->aot                    = header->profile_ObjectType + MP4A_AUDIO_OBJECT_TYPE_AAC_MAIN;
 248     summary->sbr_mode               = MP4A_AAC_SBR_NOT_SPECIFIED;
 249 #if 0 /* FIXME: This is very unstable. Many players crash with this. */
 250     if( header->ID != 0 )
 251     {
 252         /*
 253          * NOTE: This ADTS seems of ISO/IEC 13818-7 (MPEG-2 AAC).
 254          * It has special object_type_indications, depending on it's profile (Legacy Interface).
 255          * If ADIF header is not available, it should not have decoder specific information, so AudioObjectType neither.
 256          * see ISO/IEC 14496-1, DecoderSpecificInfo and 14496-3 Subpart 9: MPEG-1/2 Audio in MPEG-4.
 257          */
 258         summary->object_type_indication = header->profile_ObjectType + MP4SYS_OBJECT_TYPE_Audio_ISO_13818_7_Main_Profile;
 259         summary->aot                    = MP4A_AUDIO_OBJECT_TYPE_NULL;
 260         summary->asc                    = NULL;
 261         summary->asc_length             = 0;
 262         // summary->sbr_mode            = MP4A_AAC_SBR_NONE; /* MPEG-2 AAC should not be HE-AAC, but we forgive them. */
 263         return summary;
 264     }
 265 #endif
 266     uint32_t data_length;
 267     uint8_t *data = mp4a_export_AudioSpecificConfig( header->profile_ObjectType + MP4A_AUDIO_OBJECT_TYPE_AAC_MAIN,
 268                                                      summary->frequency, summary->channels, summary->sbr_mode,
 269                                                      NULL, 0, &data_length );
 270     if( !data )
 271     {
 272         lsmash_cleanup_summary( (lsmash_summary_t *)summary );
 273         return NULL;
 274     }
 275     lsmash_codec_specific_t *specific = lsmash_create_codec_specific_data( LSMASH_CODEC_SPECIFIC_DATA_TYPE_MP4SYS_DECODER_CONFIG,
 276                                                                            LSMASH_CODEC_SPECIFIC_FORMAT_STRUCTURED );
 277     if( !specific )
 278     {
 279         lsmash_cleanup_summary( (lsmash_summary_t *)summary );
 280         lsmash_free( data );
 281         return NULL;
 282     }
 283     lsmash_mp4sys_decoder_parameters_t *param = (lsmash_mp4sys_decoder_parameters_t *)specific->data.structured;
 284     param->objectTypeIndication = MP4SYS_OBJECT_TYPE_Audio_ISO_14496_3;
 285     param->streamType           = MP4SYS_STREAM_TYPE_AudioStream;
 286     if( lsmash_set_mp4sys_decoder_specific_info( param, data, data_length ) < 0 )
 287     {
 288         lsmash_cleanup_summary( (lsmash_summary_t *)summary );
 289         lsmash_destroy_codec_specific_data( specific );
 290         lsmash_free( data );
 291         return NULL;
 292     }
 293     lsmash_free( data );
 294     if( lsmash_add_entry( &summary->opaque->list, specific ) < 0 )
 295     {
 296         lsmash_cleanup_summary( (lsmash_summary_t *)summary );
 297         lsmash_destroy_codec_specific_data( specific );
 298         return NULL;
 299     }
 300     return summary;
 301 }
 302
 303 static int mp4sys_adts_get_accessunit
 304 (
 305     importer_t       *importer,
 306     uint32_t          track_number,
 307     lsmash_sample_t **p_sample
 308 )
 309 {
 310     if( !importer->info )
 311         return LSMASH_ERR_NAMELESS;
 312     if( track_number != 1 )
 313         return LSMASH_ERR_FUNCTION_PARAM;
 314     mp4sys_adts_importer_t *adts_imp = (mp4sys_adts_importer_t *)importer->info;
 315     importer_status current_status = importer->status;
 316     uint16_t raw_data_block_size = adts_imp->variable_header.raw_data_block_size[ adts_imp->raw_data_block_idx ];
 317     if( current_status == IMPORTER_ERROR )
 318         return LSMASH_ERR_NAMELESS;
 319     if( current_status == IMPORTER_EOF )
 320         return IMPORTER_EOF;
 321     if( current_status == IMPORTER_CHANGE )
 322     {
 323         lsmash_entry_t *entry = lsmash_get_entry( importer->summaries, track_number );
 324         if( !entry || !entry->data )
 325             return LSMASH_ERR_NAMELESS;
 326         lsmash_audio_summary_t *summary = mp4sys_adts_create_summary( &adts_imp->header );
 327         if( !summary )
 328             return LSMASH_ERR_NAMELESS;
 329         lsmash_cleanup_summary( entry->data );
 330         entry->data = summary;
 331         adts_imp->samples_in_frame = summary->samples_in_frame;
 332     }
 333     lsmash_bs_t *bs = importer->bs;
 334     /* read a raw_data_block(), typically == payload of a ADTS frame */
 335     lsmash_sample_t *sample = lsmash_create_sample( raw_data_block_size );
 336     if( !sample )
 337         return LSMASH_ERR_MEMORY_ALLOC;
 338     *p_sample = sample;
 339     if( lsmash_bs_get_bytes_ex( bs, raw_data_block_size, sample->data ) != raw_data_block_size )
 340     {
 341         importer->status = IMPORTER_ERROR;
 342         return LSMASH_ERR_INVALID_DATA;
 343     }
 344     sample->length                 = raw_data_block_size;
 345     sample->dts                    = adts_imp->au_number ++ * adts_imp->samples_in_frame;
 346     sample->cts                    = sample->dts;
 347     sample->prop.ra_flags          = ISOM_SAMPLE_RANDOM_ACCESS_FLAG_SYNC;
 348     sample->prop.pre_roll.distance = 1; /* MDCT */
 349
 350     /* now we succeeded to read current frame, so "return" takes 0 always below. */
 351
 352     /* skip adts_raw_data_block_error_check() */
 353     if( adts_imp->header.protection_absent == 0
 354      && adts_imp->variable_header.number_of_raw_data_blocks_in_frame != 0
 355      && lsmash_bs_get_bytes_ex( bs, 2, sample->data ) != 2 )
 356     {
 357         importer->status = IMPORTER_ERROR;
 358         return 0;
 359     }
 360     /* current adts_frame() has any more raw_data_block()? */
 361     if( adts_imp->raw_data_block_idx < adts_imp->variable_header.number_of_raw_data_blocks_in_frame )
 362     {
 363         adts_imp->raw_data_block_idx++;
 364         importer->status = IMPORTER_OK;
 365         return 0;
 366     }
 367     adts_imp->raw_data_block_idx = 0;
 368
 369     /* preparation for next frame */
 370
 371     uint8_t buf[MP4SYS_ADTS_MAX_FRAME_LENGTH];
 372     int64_t ret = lsmash_bs_get_bytes_ex( bs, MP4SYS_ADTS_BASIC_HEADER_LENGTH, buf );
 373     if( ret == 0 )
 374     {
 375         importer->status = IMPORTER_EOF;
 376         return 0;
 377     }
 378     if( ret != MP4SYS_ADTS_BASIC_HEADER_LENGTH )
 379     {
 380         importer->status = IMPORTER_ERROR;
 381         return 0;
 382     }
 383     /*
 384      * NOTE: About the spec of ADTS headers.
 385      * By the spec definition, ADTS's fixed header cannot change in the middle of stream.
 386      * But spec of MP4 allows that a stream(track) changes its properties in the middle of it.
 387      */
 388     /*
 389      * NOTE: About detailed check for ADTS headers.
 390      * We do not ommit detailed check for fixed header by simply testing bits' identification,
 391      * because there're some flags which does not matter to audio_summary (so AudioSpecificConfig neither)
 392      * so that we can take them as no change and never make new ObjectDescriptor.
 393      * I know that can be done with/by bitmask also and that should be fast, but L-SMASH project prefers
 394      * even foolishly straightforward way.
 395      */
 396     /*
 397      * NOTE: About our reading algorithm for ADTS.
 398      * It's rather simple if we retrieve payload of ADTS (i.e. raw AAC frame) at the same time to
 399      * retrieve headers.
 400      * But then we have to cache and memcpy every frame so that it requires more clocks and memory.
 401      * To avoid them, I adopted this separate retrieving method.
 402      */
 403     mp4sys_adts_fixed_header_t header = { 0 };
 404     mp4sys_adts_variable_header_t variable_header = { 0 };
 405     if( mp4sys_adts_parse_headers( bs, buf, &header, &variable_header ) < 0 )
 406     {
 407         importer->status = IMPORTER_ERROR;
 408         return 0;
 409     }
 410     adts_imp->variable_header = variable_header;
 411     /*
 412      * NOTE: About our support for change(s) of properties within an ADTS stream.
 413      * We have to modify these conditions depending on the features we support.
 414      * For example, if we support copyright_identification_* in any way within any feature
 415      * defined by/in any specs, such as ISO/IEC 14496-1 (MPEG-4 Systems), like...
 416      * "8.3 Intellectual Property Management and Protection (IPMP)", or something similar,
 417      * we have to check copyright_identification_* and treat them in audio_summary.
 418      * "Change(s)" may result in MP4SYS_IMPORTER_ERROR or MP4SYS_IMPORTER_CHANGE
 419      * depending on the features we support, and what the spec allows.
 420      * Sometimes the "change(s)" can be allowed, while sometimes they're forbidden.
 421      */
 422     /* currently UNsupported "change(s)". */
 423     if( adts_imp->header.profile_ObjectType != header.profile_ObjectType /* currently unsupported. */
 424      || adts_imp->header.ID != header.ID /* In strict, this means change of object_type_indication. */
 425      || adts_imp->header.sampling_frequency_index != header.sampling_frequency_index ) /* This may change timebase. */
 426     {
 427         importer->status = IMPORTER_ERROR;
 428         return 0;
 429     }
 430     /* currently supported "change(s)". */
 431     if( adts_imp->header.channel_configuration != header.channel_configuration )
 432     {
 433         /*
 434          * FIXME: About conditions of VALID "change(s)".
 435          * we have to check whether any "change(s)" affect to audioProfileLevelIndication
 436          * in InitialObjectDescriptor (MP4_IOD) or not.
 437          * If another type or upper level is required by the change(s), that is forbidden.
 438          * Because ObjectDescriptor does not have audioProfileLevelIndication,
 439          * so that it seems impossible to change audioProfileLevelIndication in the middle of the stream.
 440          * Note also any other properties, such as AudioObjectType, object_type_indication.
 441          */
 442         /*
 443          * NOTE: updating summary must be done on next call,
 444          * because user may retrieve summary right after this function call of this time,
 445          * and that should be of current, before change, one.
 446          */
 447         adts_imp->header = header;
 448         importer->status = IMPORTER_CHANGE;
 449         return 0;
 450     }
 451     /* no change which matters to mp4 muxing was found */
 452     importer->status = IMPORTER_OK;
 453     return 0;
 454 }
 455
 456 /* returns 0 if it seems adts. */
 457 static int mp4sys_adts_probe
 458 (
 459     importer_t *importer
 460 )
 461 {
 462     mp4sys_adts_importer_t *adts_imp = create_mp4sys_adts_importer( importer );
 463     if( !adts_imp )
 464         return LSMASH_ERR_MEMORY_ALLOC;
 465     int err;
 466     uint8_t buf[MP4SYS_ADTS_MAX_FRAME_LENGTH];
 467     if( lsmash_bs_get_bytes_ex( importer->bs, MP4SYS_ADTS_BASIC_HEADER_LENGTH, buf ) != MP4SYS_ADTS_BASIC_HEADER_LENGTH )
 468     {
 469         err = LSMASH_ERR_INVALID_DATA;
 470         goto fail;
 471     }
 472     mp4sys_adts_fixed_header_t    header          = { 0 };
 473     mp4sys_adts_variable_header_t variable_header = { 0 };
 474     if( (err = mp4sys_adts_parse_headers( importer->bs, buf, &header, &variable_header )) < 0 )
 475         goto fail;
 476     /* now the stream seems valid ADTS */
 477     lsmash_audio_summary_t *summary = mp4sys_adts_create_summary( &header );
 478     if( !summary )
 479     {
 480         err = LSMASH_ERR_NAMELESS;
 481         goto fail;
 482     }
 483     /* importer status */
 484     if( lsmash_add_entry( importer->summaries, summary ) < 0 )
 485     {
 486         lsmash_cleanup_summary( (lsmash_summary_t *)summary );
 487         err = LSMASH_ERR_MEMORY_ALLOC;
 488         goto fail;
 489     }
 490     adts_imp->raw_data_block_idx = 0;
 491     adts_imp->header             = header;
 492     adts_imp->variable_header    = variable_header;
 493     adts_imp->samples_in_frame   = summary->samples_in_frame;
 494     importer->info   = adts_imp;
 495     importer->status = IMPORTER_OK;
 496     return 0;
 497 fail:
 498     remove_mp4sys_adts_importer( adts_imp );
 499     return err;
 500 }
 501
 502 static uint32_t mp4sys_adts_get_last_delta
 503 (
 504     importer_t *importer,
 505     uint32_t    track_number
 506 )
 507 {
 508     debug_if( !importer || !importer->info )
 509         return 0;
 510     mp4sys_adts_importer_t *adts_imp = (mp4sys_adts_importer_t *)importer->info;
 511     if( !adts_imp || track_number != 1 || importer->status != IMPORTER_EOF )
 512         return 0;
 513     return adts_imp->samples_in_frame;
 514 }
 515
 516 const importer_functions mp4sys_adts_importer =
 517 {
 518     { "adts" },
 519     1,
 520     mp4sys_adts_probe,
 521     mp4sys_adts_get_accessunit,
 522     mp4sys_adts_get_last_delta,
 523     mp4sys_adts_cleanup
 524 };