apps/metadata/mp4.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2005 Magnus Holmgren
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <stdlib.h>
  24 #include <ctype.h>
  25 #include <inttypes.h>
  26
  27 #include "system.h"
  28 #include "errno.h"
  29 #include "metadata.h"
  30 #include "metadata_common.h"
  31 #include "metadata_parsers.h"
  32 #include "logf.h"
  33 #include "debug.h"
  34 #include "replaygain.h"
  35
  36 #define MP4_3gp6 FOURCC('3', 'g', 'p', '6')
  37 #define MP4_aART FOURCC('a', 'A', 'R', 'T')
  38 #define MP4_alac FOURCC('a', 'l', 'a', 'c')
  39 #define MP4_calb FOURCC(0xa9, 'a', 'l', 'b')
  40 #define MP4_cART FOURCC(0xa9, 'A', 'R', 'T')
  41 #define MP4_cgrp FOURCC(0xa9, 'g', 'r', 'p')
  42 #define MP4_cgen FOURCC(0xa9, 'g', 'e', 'n')
  43 #define MP4_chpl FOURCC('c', 'h', 'p', 'l')
  44 #define MP4_cnam FOURCC(0xa9, 'n', 'a', 'm')
  45 #define MP4_cwrt FOURCC(0xa9, 'w', 'r', 't')
  46 #define MP4_ccmt FOURCC(0xa9, 'c', 'm', 't')
  47 #define MP4_cday FOURCC(0xa9, 'd', 'a', 'y')
  48 #define MP4_disk FOURCC('d', 'i', 's', 'k')
  49 #define MP4_esds FOURCC('e', 's', 'd', 's')
  50 #define MP4_ftyp FOURCC('f', 't', 'y', 'p')
  51 #define MP4_gnre FOURCC('g', 'n', 'r', 'e')
  52 #define MP4_hdlr FOURCC('h', 'd', 'l', 'r')
  53 #define MP4_ilst FOURCC('i', 'l', 's', 't')
  54 #define MP4_isom FOURCC('i', 's', 'o', 'm')
  55 #define MP4_M4A  FOURCC('M', '4', 'A', ' ')
  56 #define MP4_m4a  FOURCC('m', '4', 'a', ' ') /*technically its "M4A "*/
  57 #define MP4_M4B  FOURCC('M', '4', 'B', ' ') /*but files exist with lower case*/
  58 #define MP4_mdat FOURCC('m', 'd', 'a', 't')
  59 #define MP4_mdia FOURCC('m', 'd', 'i', 'a')
  60 #define MP4_mdir FOURCC('m', 'd', 'i', 'r')
  61 #define MP4_meta FOURCC('m', 'e', 't', 'a')
  62 #define MP4_minf FOURCC('m', 'i', 'n', 'f')
  63 #define MP4_moov FOURCC('m', 'o', 'o', 'v')
  64 #define MP4_mp4a FOURCC('m', 'p', '4', 'a')
  65 #define MP4_mp42 FOURCC('m', 'p', '4', '2')
  66 #define MP4_qt   FOURCC('q', 't', ' ', ' ')
  67 #define MP4_soun FOURCC('s', 'o', 'u', 'n')
  68 #define MP4_stbl FOURCC('s', 't', 'b', 'l')
  69 #define MP4_stsd FOURCC('s', 't', 's', 'd')
  70 #define MP4_stts FOURCC('s', 't', 't', 's')
  71 #define MP4_trak FOURCC('t', 'r', 'a', 'k')
  72 #define MP4_trkn FOURCC('t', 'r', 'k', 'n')
  73 #define MP4_udta FOURCC('u', 'd', 't', 'a')
  74 #define MP4_extra FOURCC('-', '-', '-', '-')
  75
  76 /* Read the tag data from an MP4 file, storing up to buffer_size bytes in
  77  * buffer.
  78  */
  79 static unsigned long read_mp4_tag(int fd, unsigned int size_left, char* buffer,
  80                                   unsigned int buffer_left)
  81 {
  82     unsigned int bytes_read = 0;
  83
  84     if (buffer_left == 0)
  85     {
  86         lseek(fd, size_left, SEEK_CUR);     /* Skip everything */
  87     }
  88     else
  89     {
  90         /* Skip the data tag header - maybe we should parse it properly? */
  91         lseek(fd, 16, SEEK_CUR);
  92         size_left -= 16;
  93
  94         if (size_left > buffer_left)
  95         {
  96             read(fd, buffer, buffer_left);
  97             lseek(fd, size_left - buffer_left, SEEK_CUR);
  98             bytes_read = buffer_left;
  99         }
 100         else
 101         {
 102             read(fd, buffer, size_left);
 103             bytes_read = size_left;
 104         }
 105     }
 106
 107     return bytes_read;
 108 }
 109
 110 /* Read a string tag from an MP4 file */
 111 static unsigned int read_mp4_tag_string(int fd, int size_left, char** buffer,
 112                                         unsigned int* buffer_left, char** dest)
 113 {
 114     unsigned int bytes_read = read_mp4_tag(fd, size_left, *buffer,
 115         *buffer_left > 0 ? *buffer_left - 1 : 0);
 116     unsigned int length = 0;
 117
 118     if (bytes_read)
 119     {
 120         (*buffer)[bytes_read] = 0;
 121         *dest = *buffer;
 122         length = strlen(*buffer) + 1;
 123         *buffer_left -= length;
 124         *buffer += length;
 125     }
 126     else
 127     {
 128         *dest = NULL;
 129     }
 130
 131     return length;
 132 }
 133
 134 static unsigned int read_mp4_atom(int fd, uint32_t* size,
 135                                   uint32_t* type, uint32_t size_left)
 136 {
 137     read_uint32be(fd, size);
 138     read_uint32be(fd, type);
 139
 140     if (*size == 1)
 141     {
 142         /* FAT32 doesn't support files this big, so something seems to
 143          * be wrong. (64-bit sizes should only be used when required.)
 144          */
 145         errno = EFBIG;
 146         *type = 0;
 147         return 0;
 148     }
 149
 150     if (*size > 0)
 151     {
 152         if (*size > size_left)
 153         {
 154             size_left = 0;
 155         }
 156         else
 157         {
 158             size_left -= *size;
 159         }
 160
 161         *size -= 8;
 162     }
 163     else
 164     {
 165         *size = size_left;
 166         size_left = 0;
 167     }
 168
 169     return size_left;
 170 }
 171
 172 static unsigned int read_mp4_length(int fd, uint32_t* size)
 173 {
 174     unsigned int length = 0;
 175     int bytes = 0;
 176     unsigned char c;
 177
 178     do
 179     {
 180         read(fd, &c, 1);
 181         bytes++;
 182         (*size)--;
 183         length = (length << 7) | (c & 0x7F);
 184     }
 185     while ((c & 0x80) && (bytes < 4) && (*size > 0));
 186
 187     return length;
 188 }
 189
 190 static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
 191 {
 192     unsigned char buf[8];
 193     bool sbr = false;
 194
 195     lseek(fd, 4, SEEK_CUR);     /* Version and flags. */
 196     read(fd, buf, 1);           /* Verify ES_DescrTag. */
 197     *size -= 5;
 198
 199     if (*buf == 3)
 200     {
 201         /* read length */
 202         if (read_mp4_length(fd, size) < 20)
 203         {
 204             return sbr;
 205         }
 206
 207         lseek(fd, 3, SEEK_CUR);
 208         *size -= 3;
 209     }
 210     else
 211     {
 212         lseek(fd, 2, SEEK_CUR);
 213         *size -= 2;
 214     }
 215
 216     read(fd, buf, 1);           /* Verify DecoderConfigDescrTab. */
 217     *size -= 1;
 218
 219     if (*buf != 4)
 220     {
 221         return sbr;
 222     }
 223
 224     if (read_mp4_length(fd, size) < 13)
 225     {
 226         return sbr;
 227     }
 228
 229     lseek(fd, 13, SEEK_CUR);    /* Skip audio type, bit rates, etc. */
 230     read(fd, buf, 1);
 231     *size -= 14;
 232
 233     if (*buf != 5)              /* Verify DecSpecificInfoTag. */
 234     {
 235         return sbr;
 236     }
 237
 238     {
 239         static const int sample_rates[] =
 240         {
 241             96000, 88200, 64000, 48000, 44100, 32000,
 242             24000, 22050, 16000, 12000, 11025, 8000
 243         };
 244         unsigned long bits;
 245         unsigned int length;
 246         unsigned int index;
 247         unsigned int type;
 248
 249         /* Read the (leading part of the) decoder config. */
 250         length = read_mp4_length(fd, size);
 251         length = MIN(length, *size);
 252         length = MIN(length, sizeof(buf));
 253         memset(buf, 0, sizeof(buf));
 254         read(fd, buf, length);
 255         *size -= length;
 256
 257         /* Maybe time to write a simple read_bits function... */
 258
 259         /* Decoder config format:
 260          * Object type           - 5 bits
 261          * Frequency index       - 4 bits
 262          * Channel configuration - 4 bits
 263          */
 264         bits = get_long_be(buf);
 265         type = bits >> 27;              /* Object type - 5 bits */
 266         index = (bits >> 23) & 0xf;     /* Frequency index - 4 bits */
 267
 268         if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 269         {
 270             id3->frequency = sample_rates[index];
 271         }
 272
 273         if (type == 5)
 274         {
 275             DEBUGF("MP4: SBR\n");
 276             unsigned int old_index = index;
 277
 278             sbr = true;
 279             index = (bits >> 15) & 0xf; /* Frequency index - 4 bits */
 280
 281             if (index == 15)
 282             {
 283                 /* 17 bits read so far... */
 284                 bits = get_long_be(&buf[2]);
 285                 id3->frequency = (bits >> 7) & 0x00ffffff;
 286             }
 287             else if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 288             {
 289                 id3->frequency = sample_rates[index];
 290             }
 291
 292             if (old_index == index)
 293             {
 294                 /* Downsampled SBR */
 295                 id3->frequency *= 2;
 296             }
 297         }
 298         /* Skip 13 bits from above, plus 3 bits, then read 11 bits */
 299         else if ((length >= 4) && (((bits >> 5) & 0x7ff) == 0x2b7))
 300         {
 301             /* extensionAudioObjectType */
 302             DEBUGF("MP4: extensionAudioType\n");
 303             type = bits & 0x1f;         /* Object type - 5 bits*/
 304             bits = get_long_be(&buf[4]);
 305
 306             if (type == 5)
 307             {
 308                 sbr = bits >> 31;
 309
 310                 if (sbr)
 311                 {
 312                     unsigned int old_index = index;
 313
 314                     /* 1 bit read so far */
 315                     index = (bits >> 27) & 0xf; /* Frequency index - 4 bits */
 316
 317                     if (index == 15)
 318                     {
 319                         /* 5 bits read so far */
 320                         id3->frequency = (bits >> 3) & 0x00ffffff;
 321                     }
 322                     else if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 323                     {
 324                         id3->frequency = sample_rates[index];
 325                     }
 326
 327                     if (old_index == index)
 328                     {
 329                         /* Downsampled SBR */
 330                         id3->frequency *= 2;
 331                     }
 332                 }
 333             }
 334         }
 335
 336         if (!sbr && (id3->frequency <= 24000) && (length <= 2))
 337         {
 338             /* Double the frequency for low-frequency files without a "long"
 339              * DecSpecificConfig header. The file may or may not contain SBR,
 340              * but here we guess it does if the header is short. This can
 341              * fail on some files, but it's the best we can do, short of
 342              * decoding (parts of) the file.
 343              */
 344             id3->frequency *= 2;
 345         }
 346     }
 347
 348     return sbr;
 349 }
 350
 351 static bool read_mp4_tags(int fd, struct mp3entry* id3,
 352                           uint32_t size_left)
 353 {
 354     uint32_t size;
 355     uint32_t type;
 356     unsigned int buffer_left = sizeof(id3->id3v2buf) + sizeof(id3->id3v1buf);
 357     char* buffer = id3->id3v2buf;
 358     bool cwrt = false;
 359
 360     do
 361     {
 362         size_left = read_mp4_atom(fd, &size, &type, size_left);
 363
 364         /* DEBUGF("Tag atom: '%c%c%c%c' (%d bytes left)\n", type >> 24 & 0xff,
 365             type >> 16 & 0xff, type >> 8 & 0xff, type & 0xff, size); */
 366
 367         switch (type)
 368         {
 369         case MP4_cnam:
 370             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 371                 &id3->title);
 372             break;
 373
 374         case MP4_cART:
 375             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 376                 &id3->artist);
 377             break;
 378
 379         case MP4_aART:
 380             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 381                 &id3->albumartist);
 382             break;
 383
 384         case MP4_cgrp:
 385             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 386                 &id3->grouping);
 387             break;
 388
 389         case MP4_calb:
 390             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 391                 &id3->album);
 392             break;
 393
 394         case MP4_cwrt:
 395             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 396                 &id3->composer);
 397             cwrt = false;
 398             break;
 399
 400         case MP4_ccmt:
 401             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 402                 &id3->comment);
 403             break;
 404
 405         case MP4_cday:
 406             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 407                                 &id3->year_string);
 408
 409             /* Try to parse it as a year, for the benefit of the database.
 410              */
 411             if(id3->year_string)
 412             {
 413                 id3->year = atoi(id3->year_string);
 414                 if (id3->year < 1900)
 415                 {
 416                     id3->year = 0;
 417                 }
 418             }
 419             else
 420                 id3->year = 0;
 421
 422             break;
 423
 424         case MP4_gnre:
 425             {
 426                 unsigned short genre;
 427
 428                 read_mp4_tag(fd, size, (char*) &genre, sizeof(genre));
 429                 id3->genre_string = id3_get_num_genre(betoh16(genre) - 1);
 430             }
 431             break;
 432
 433         case MP4_cgen:
 434             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 435                 &id3->genre_string);
 436             break;
 437
 438         case MP4_disk:
 439             {
 440                 unsigned short n[2];
 441
 442                 read_mp4_tag(fd, size, (char*) &n, sizeof(n));
 443                 id3->discnum = betoh16(n[1]);
 444             }
 445             break;
 446
 447         case MP4_trkn:
 448             {
 449                 unsigned short n[2];
 450
 451                 read_mp4_tag(fd, size, (char*) &n, sizeof(n));
 452                 id3->tracknum = betoh16(n[1]);
 453             }
 454             break;
 455
 456         case MP4_extra:
 457             {
 458                 char tag_name[TAG_NAME_LENGTH];
 459                 uint32_t sub_size;
 460
 461                 /* "mean" atom */
 462                 read_uint32be(fd, &sub_size);
 463                 size -= sub_size;
 464                 lseek(fd, sub_size - 4, SEEK_CUR);
 465                 /* "name" atom */
 466                 read_uint32be(fd, &sub_size);
 467                 size -= sub_size;
 468                 lseek(fd, 8, SEEK_CUR);
 469                 sub_size -= 12;
 470
 471                 if (sub_size > sizeof(tag_name) - 1)
 472                 {
 473                     read(fd, tag_name, sizeof(tag_name) - 1);
 474                     lseek(fd, sub_size - (sizeof(tag_name) - 1), SEEK_CUR);
 475                     tag_name[sizeof(tag_name) - 1] = 0;
 476                 }
 477                 else
 478                 {
 479                     read(fd, tag_name, sub_size);
 480                     tag_name[sub_size] = 0;
 481                 }
 482
 483                 if ((strcasecmp(tag_name, "composer") == 0) && !cwrt)
 484                 {
 485                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 486                         &id3->composer);
 487                 }
 488                 else if (strcasecmp(tag_name, "iTunSMPB") == 0)
 489                 {
 490                     char value[TAG_VALUE_LENGTH];
 491                     char* value_p = value;
 492                     char* any;
 493                     unsigned int length = sizeof(value);
 494
 495                     read_mp4_tag_string(fd, size, &value_p, &length, &any);
 496                     id3->lead_trim = get_itunes_int32(value, 1);
 497                     id3->tail_trim = get_itunes_int32(value, 2);
 498                     DEBUGF("AAC: lead_trim %d, tail_trim %d\n",
 499                         id3->lead_trim, id3->tail_trim);
 500                 }
 501                 else if (strcasecmp(tag_name, "musicbrainz track id") == 0)
 502                 {
 503                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 504                         &id3->mb_track_id);
 505                 }
 506                 else if ((strcasecmp(tag_name, "album artist") == 0))
 507                 {
 508                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 509                         &id3->albumartist);
 510                 }
 511                 else
 512                 {
 513                     char* any;
 514                     unsigned int length = read_mp4_tag_string(fd, size,
 515                         &buffer, &buffer_left, &any);
 516
 517                     if (length > 0)
 518                     {
 519                         /* Re-use the read buffer as the dest buffer... */
 520                         buffer -= length;
 521                         buffer_left += length;
 522
 523                         if (parse_replaygain(tag_name, buffer, id3,
 524                             buffer, buffer_left) > 0)
 525                         {
 526                             /* Data used, keep it. */
 527                             buffer += length;
 528                             buffer_left -= length;
 529                         }
 530                     }
 531                 }
 532             }
 533             break;
 534
 535         default:
 536             lseek(fd, size, SEEK_CUR);
 537             break;
 538         }
 539     }
 540     while ((size_left > 0) && (errno == 0));
 541
 542     return true;
 543 }
 544
 545 static bool read_mp4_container(int fd, struct mp3entry* id3,
 546                                uint32_t size_left)
 547 {
 548     uint32_t size;
 549     uint32_t type;
 550     uint32_t handler = 0;
 551     bool rc = true;
 552     bool done = false;
 553
 554     do
 555     {
 556         size_left = read_mp4_atom(fd, &size, &type, size_left);
 557
 558         /* DEBUGF("Atom: '%c%c%c%c' (0x%08lx, %lu bytes left)\n",
 559             (int) ((type >> 24) & 0xff), (int) ((type >> 16) & 0xff),
 560             (int) ((type >> 8) & 0xff), (int) (type & 0xff),
 561             type, size); */
 562
 563         switch (type)
 564         {
 565         case MP4_ftyp:
 566             {
 567                 uint32_t id;
 568
 569                 read_uint32be(fd, &id);
 570                 size -= 4;
 571
 572                 if ((id != MP4_M4A) && (id != MP4_M4B) && (id != MP4_mp42)
 573                     && (id != MP4_qt) && (id != MP4_3gp6) && (id != MP4_m4a)
 574                     && (id != MP4_isom))
 575                 {
 576                     DEBUGF("Unknown MP4 file type: '%c%c%c%c'\n",
 577                         (int)(id >> 24 & 0xff), (int)(id >> 16 & 0xff),
 578                         (int)(id >> 8 & 0xff), (int)(id & 0xff));
 579                     return false;
 580                 }
 581             }
 582             break;
 583
 584         case MP4_meta:
 585             lseek(fd, 4, SEEK_CUR);  /* Skip version */
 586             size -= 4;
 587             /* Fall through */
 588
 589         case MP4_moov:
 590         case MP4_udta:
 591         case MP4_mdia:
 592         case MP4_stbl:
 593         case MP4_trak:
 594             rc = read_mp4_container(fd, id3, size);
 595             size = 0;
 596             break;
 597
 598         case MP4_ilst:
 599             if (handler == MP4_mdir)
 600             {
 601                 rc = read_mp4_tags(fd, id3, size);
 602                 size = 0;
 603             }
 604             break;
 605
 606         case MP4_minf:
 607             if (handler == MP4_soun)
 608             {
 609                 rc = read_mp4_container(fd, id3, size);
 610                 size = 0;
 611             }
 612             break;
 613
 614         case MP4_stsd:
 615             lseek(fd, 8, SEEK_CUR);
 616             size -= 8;
 617             rc = read_mp4_container(fd, id3, size);
 618             size = 0;
 619             break;
 620
 621         case MP4_hdlr:
 622             lseek(fd, 8, SEEK_CUR);
 623             read_uint32be(fd, &handler);
 624             size -= 12;
 625             /* DEBUGF("    Handler '%c%c%c%c'\n", handler >> 24 & 0xff,
 626                 handler >> 16 & 0xff, handler >> 8 & 0xff,handler & 0xff); */
 627             break;
 628
 629         case MP4_stts:
 630             {
 631                 uint32_t entries;
 632                 unsigned int i;
 633
 634                 lseek(fd, 4, SEEK_CUR);
 635                 read_uint32be(fd, &entries);
 636                 id3->samples = 0;
 637
 638                 for (i = 0; i < entries; i++)
 639                 {
 640                     uint32_t n;
 641                     uint32_t l;
 642
 643                     read_uint32be(fd, &n);
 644                     read_uint32be(fd, &l);
 645                     id3->samples += n * l;
 646                 }
 647
 648                 size = 0;
 649             }
 650             break;
 651
 652         case MP4_mp4a:
 653         case MP4_alac:
 654             {
 655                 uint32_t frequency;
 656
 657                 id3->codectype = (type == MP4_mp4a) ? AFMT_MP4_AAC : AFMT_MP4_ALAC;
 658                 lseek(fd, 22, SEEK_CUR);
 659                 read_uint32be(fd, &frequency);
 660                 size -= 26;
 661                 id3->frequency = frequency;
 662
 663                 if (type == MP4_mp4a)
 664                 {
 665                     uint32_t subsize;
 666                     uint32_t subtype;
 667
 668                     /* Get frequency from the decoder info tag, if possible. */
 669                     lseek(fd, 2, SEEK_CUR);
 670                     /* The esds atom is a part of the mp4a atom, so ignore
 671                      * the returned size (it's already accounted for).
 672                      */
 673                     read_mp4_atom(fd, &subsize, &subtype, size);
 674                     size -= 10;
 675
 676                     if (subtype == MP4_esds)
 677                     {
 678                         read_mp4_esds(fd, id3, &size);
 679                     }
 680                 }
 681             }
 682             break;
 683
 684         case MP4_mdat:
 685             /* Some AAC files appear to contain additional empty mdat chunks.
 686                Ignore them. */
 687             if(size == 0)
 688                 break;
 689             id3->filesize = size;
 690             if(id3->samples > 0) {
 691                 /* We've already seen the moov chunk. */
 692                 done = true;
 693             }
 694             break;
 695
 696         case MP4_chpl:
 697             {
 698                 /* ADDME: add support for real chapters. Right now it's only
 699                  * used for Nero's gapless hack */
 700                 uint8_t chapters;
 701                 uint64_t timestamp;
 702
 703                 lseek(fd, 8, SEEK_CUR);
 704                 read_uint8(fd, &chapters);
 705                 size -= 9;
 706
 707                 /* the first chapter will be used as the lead_trim */
 708                 if (chapters > 0) {
 709                     read_uint64be(fd, &timestamp);
 710                     id3->lead_trim = (timestamp * id3->frequency) / 10000000;
 711                     size -= 8;
 712                 }
 713             }
 714             break;
 715
 716         default:
 717             break;
 718         }
 719
 720         /* Skip final seek. */
 721         if (!done)
 722         {
 723             lseek(fd, size, SEEK_CUR);
 724         }
 725     } while (rc && (size_left > 0) && (errno == 0) && !done);
 726
 727     return rc;
 728 }
 729
 730 bool get_mp4_metadata(int fd, struct mp3entry* id3)
 731 {
 732     id3->codectype = AFMT_UNKNOWN;
 733     id3->filesize = 0;
 734     errno = 0;
 735
 736     if (read_mp4_container(fd, id3, filesize(fd)) && (errno == 0)
 737         && (id3->samples > 0) && (id3->frequency > 0)
 738         && (id3->filesize > 0))
 739     {
 740         if (id3->codectype == AFMT_UNKNOWN)
 741         {
 742             logf("Not an ALAC or AAC file");
 743             return false;
 744         }
 745
 746         id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
 747
 748         if (id3->length <= 0)
 749         {
 750             logf("mp4 length invalid!");
 751             return false;
 752         }
 753
 754         id3->bitrate = ((int64_t) id3->filesize * 8) / id3->length;
 755         DEBUGF("MP4 bitrate %d, frequency %ld Hz, length %ld ms\n",
 756             id3->bitrate, id3->frequency, id3->length);
 757     }
 758     else
 759     {
 760         logf("MP4 metadata error");
 761         DEBUGF("MP4 metadata error. errno %d, samples %ld, frequency %ld, "
 762             "filesize %ld\n", errno, id3->samples, id3->frequency,
 763             id3->filesize);
 764         return false;
 765     }
 766
 767     return true;
 768 }