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_M4B  FOURCC('M', '4', 'B', ' ')
  57 #define MP4_mdat FOURCC('m', 'd', 'a', 't')
  58 #define MP4_mdia FOURCC('m', 'd', 'i', 'a')
  59 #define MP4_mdir FOURCC('m', 'd', 'i', 'r')
  60 #define MP4_meta FOURCC('m', 'e', 't', 'a')
  61 #define MP4_minf FOURCC('m', 'i', 'n', 'f')
  62 #define MP4_moov FOURCC('m', 'o', 'o', 'v')
  63 #define MP4_mp4a FOURCC('m', 'p', '4', 'a')
  64 #define MP4_mp42 FOURCC('m', 'p', '4', '2')
  65 #define MP4_qt   FOURCC('q', 't', ' ', ' ')
  66 #define MP4_soun FOURCC('s', 'o', 'u', 'n')
  67 #define MP4_stbl FOURCC('s', 't', 'b', 'l')
  68 #define MP4_stsd FOURCC('s', 't', 's', 'd')
  69 #define MP4_stts FOURCC('s', 't', 't', 's')
  70 #define MP4_trak FOURCC('t', 'r', 'a', 'k')
  71 #define MP4_trkn FOURCC('t', 'r', 'k', 'n')
  72 #define MP4_udta FOURCC('u', 'd', 't', 'a')
  73 #define MP4_extra FOURCC('-', '-', '-', '-')
  74
  75 /* Read the tag data from an MP4 file, storing up to buffer_size bytes in
  76  * buffer.
  77  */
  78 static unsigned long read_mp4_tag(int fd, unsigned int size_left, char* buffer,
  79                                   unsigned int buffer_left)
  80 {
  81     unsigned int bytes_read = 0;
  82
  83     if (buffer_left == 0)
  84     {
  85         lseek(fd, size_left, SEEK_CUR);     /* Skip everything */
  86     }
  87     else
  88     {
  89         /* Skip the data tag header - maybe we should parse it properly? */
  90         lseek(fd, 16, SEEK_CUR);
  91         size_left -= 16;
  92
  93         if (size_left > buffer_left)
  94         {
  95             read(fd, buffer, buffer_left);
  96             lseek(fd, size_left - buffer_left, SEEK_CUR);
  97             bytes_read = buffer_left;
  98         }
  99         else
 100         {
 101             read(fd, buffer, size_left);
 102             bytes_read = size_left;
 103         }
 104     }
 105
 106     return bytes_read;
 107 }
 108
 109 /* Read a string tag from an MP4 file */
 110 static unsigned int read_mp4_tag_string(int fd, int size_left, char** buffer,
 111                                         unsigned int* buffer_left, char** dest)
 112 {
 113     unsigned int bytes_read = read_mp4_tag(fd, size_left, *buffer,
 114         *buffer_left > 0 ? *buffer_left - 1 : 0);
 115     unsigned int length = 0;
 116
 117     if (bytes_read)
 118     {
 119         (*buffer)[bytes_read] = 0;
 120         *dest = *buffer;
 121         length = strlen(*buffer) + 1;
 122         *buffer_left -= length;
 123         *buffer += length;
 124     }
 125     else
 126     {
 127         *dest = NULL;
 128     }
 129
 130     return length;
 131 }
 132
 133 static unsigned int read_mp4_atom(int fd, uint32_t* size,
 134                                   uint32_t* type, uint32_t size_left)
 135 {
 136     read_uint32be(fd, size);
 137     read_uint32be(fd, type);
 138
 139     if (*size == 1)
 140     {
 141         /* FAT32 doesn't support files this big, so something seems to
 142          * be wrong. (64-bit sizes should only be used when required.)
 143          */
 144         errno = EFBIG;
 145         *type = 0;
 146         return 0;
 147     }
 148
 149     if (*size > 0)
 150     {
 151         if (*size > size_left)
 152         {
 153             size_left = 0;
 154         }
 155         else
 156         {
 157             size_left -= *size;
 158         }
 159
 160         *size -= 8;
 161     }
 162     else
 163     {
 164         *size = size_left;
 165         size_left = 0;
 166     }
 167
 168     return size_left;
 169 }
 170
 171 static unsigned int read_mp4_length(int fd, uint32_t* size)
 172 {
 173     unsigned int length = 0;
 174     int bytes = 0;
 175     unsigned char c;
 176
 177     do
 178     {
 179         read(fd, &c, 1);
 180         bytes++;
 181         (*size)--;
 182         length = (length << 7) | (c & 0x7F);
 183     }
 184     while ((c & 0x80) && (bytes < 4) && (*size > 0));
 185
 186     return length;
 187 }
 188
 189 static bool read_mp4_esds(int fd, struct mp3entry* id3, uint32_t* size)
 190 {
 191     unsigned char buf[8];
 192     bool sbr = false;
 193
 194     lseek(fd, 4, SEEK_CUR);     /* Version and flags. */
 195     read(fd, buf, 1);           /* Verify ES_DescrTag. */
 196     *size -= 5;
 197
 198     if (*buf == 3)
 199     {
 200         /* read length */
 201         if (read_mp4_length(fd, size) < 20)
 202         {
 203             return sbr;
 204         }
 205
 206         lseek(fd, 3, SEEK_CUR);
 207         *size -= 3;
 208     }
 209     else
 210     {
 211         lseek(fd, 2, SEEK_CUR);
 212         *size -= 2;
 213     }
 214
 215     read(fd, buf, 1);           /* Verify DecoderConfigDescrTab. */
 216     *size -= 1;
 217
 218     if (*buf != 4)
 219     {
 220         return sbr;
 221     }
 222
 223     if (read_mp4_length(fd, size) < 13)
 224     {
 225         return sbr;
 226     }
 227
 228     lseek(fd, 13, SEEK_CUR);    /* Skip audio type, bit rates, etc. */
 229     read(fd, buf, 1);
 230     *size -= 14;
 231
 232     if (*buf != 5)              /* Verify DecSpecificInfoTag. */
 233     {
 234         return sbr;
 235     }
 236
 237     {
 238         static const int sample_rates[] =
 239         {
 240             96000, 88200, 64000, 48000, 44100, 32000,
 241             24000, 22050, 16000, 12000, 11025, 8000
 242         };
 243         unsigned long bits;
 244         unsigned int length;
 245         unsigned int index;
 246         unsigned int type;
 247
 248         /* Read the (leading part of the) decoder config. */
 249         length = read_mp4_length(fd, size);
 250         length = MIN(length, *size);
 251         length = MIN(length, sizeof(buf));
 252         memset(buf, 0, sizeof(buf));
 253         read(fd, buf, length);
 254         *size -= length;
 255
 256         /* Maybe time to write a simple read_bits function... */
 257
 258         /* Decoder config format:
 259          * Object type           - 5 bits
 260          * Frequency index       - 4 bits
 261          * Channel configuration - 4 bits
 262          */
 263         bits = get_long_be(buf);
 264         type = bits >> 27;              /* Object type - 5 bits */
 265         index = (bits >> 23) & 0xf;     /* Frequency index - 4 bits */
 266
 267         if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 268         {
 269             id3->frequency = sample_rates[index];
 270         }
 271
 272         if (type == 5)
 273         {
 274             DEBUGF("MP4: SBR\n");
 275             unsigned int old_index = index;
 276
 277             sbr = true;
 278             index = (bits >> 15) & 0xf; /* Frequency index - 4 bits */
 279
 280             if (index == 15)
 281             {
 282                 /* 17 bits read so far... */
 283                 bits = get_long_be(&buf[2]);
 284                 id3->frequency = (bits >> 7) & 0x00ffffff;
 285             }
 286             else if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 287             {
 288                 id3->frequency = sample_rates[index];
 289             }
 290
 291             if (old_index == index)
 292             {
 293                 /* Downsampled SBR */
 294                 id3->frequency *= 2;
 295             }
 296         }
 297         /* Skip 13 bits from above, plus 3 bits, then read 11 bits */
 298         else if ((length >= 4) && (((bits >> 5) & 0x7ff) == 0x2b7))
 299         {
 300             /* extensionAudioObjectType */
 301             DEBUGF("MP4: extensionAudioType\n");
 302             type = bits & 0x1f;         /* Object type - 5 bits*/
 303             bits = get_long_be(&buf[4]);
 304
 305             if (type == 5)
 306             {
 307                 sbr = bits >> 31;
 308
 309                 if (sbr)
 310                 {
 311                     unsigned int old_index = index;
 312
 313                     /* 1 bit read so far */
 314                     index = (bits >> 27) & 0xf; /* Frequency index - 4 bits */
 315
 316                     if (index == 15)
 317                     {
 318                         /* 5 bits read so far */
 319                         id3->frequency = (bits >> 3) & 0x00ffffff;
 320                     }
 321                     else if (index < (sizeof(sample_rates) / sizeof(*sample_rates)))
 322                     {
 323                         id3->frequency = sample_rates[index];
 324                     }
 325
 326                     if (old_index == index)
 327                     {
 328                         /* Downsampled SBR */
 329                         id3->frequency *= 2;
 330                     }
 331                 }
 332             }
 333         }
 334
 335         if (!sbr && (id3->frequency <= 24000) && (length <= 2))
 336         {
 337             /* Double the frequency for low-frequency files without a "long"
 338              * DecSpecificConfig header. The file may or may not contain SBR,
 339              * but here we guess it does if the header is short. This can
 340              * fail on some files, but it's the best we can do, short of
 341              * decoding (parts of) the file.
 342              */
 343             id3->frequency *= 2;
 344         }
 345     }
 346
 347     return sbr;
 348 }
 349
 350 static bool read_mp4_tags(int fd, struct mp3entry* id3,
 351                           uint32_t size_left)
 352 {
 353     uint32_t size;
 354     uint32_t type;
 355     unsigned int buffer_left = sizeof(id3->id3v2buf) + sizeof(id3->id3v1buf);
 356     char* buffer = id3->id3v2buf;
 357     bool cwrt = false;
 358
 359     do
 360     {
 361         size_left = read_mp4_atom(fd, &size, &type, size_left);
 362
 363         /* DEBUGF("Tag atom: '%c%c%c%c' (%d bytes left)\n", type >> 24 & 0xff,
 364             type >> 16 & 0xff, type >> 8 & 0xff, type & 0xff, size); */
 365
 366         switch (type)
 367         {
 368         case MP4_cnam:
 369             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 370                 &id3->title);
 371             break;
 372
 373         case MP4_cART:
 374             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 375                 &id3->artist);
 376             break;
 377
 378         case MP4_aART:
 379             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 380                 &id3->albumartist);
 381             break;
 382
 383         case MP4_cgrp:
 384             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 385                 &id3->grouping);
 386             break;
 387
 388         case MP4_calb:
 389             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 390                 &id3->album);
 391             break;
 392
 393         case MP4_cwrt:
 394             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 395                 &id3->composer);
 396             cwrt = false;
 397             break;
 398
 399         case MP4_ccmt:
 400             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 401                 &id3->comment);
 402             break;
 403
 404         case MP4_cday:
 405             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 406                                 &id3->year_string);
 407
 408             /* Try to parse it as a year, for the benefit of the database.
 409              */
 410             if(id3->year_string)
 411             {
 412                 id3->year = atoi(id3->year_string);
 413                 if (id3->year < 1900)
 414                 {
 415                     id3->year = 0;
 416                 }
 417             }
 418             else
 419                 id3->year = 0;
 420
 421             break;
 422
 423         case MP4_gnre:
 424             {
 425                 unsigned short genre;
 426
 427                 read_mp4_tag(fd, size, (char*) &genre, sizeof(genre));
 428                 id3->genre_string = id3_get_num_genre(betoh16(genre) - 1);
 429             }
 430             break;
 431
 432         case MP4_cgen:
 433             read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 434                 &id3->genre_string);
 435             break;
 436
 437         case MP4_disk:
 438             {
 439                 unsigned short n[2];
 440
 441                 read_mp4_tag(fd, size, (char*) &n, sizeof(n));
 442                 id3->discnum = betoh16(n[1]);
 443             }
 444             break;
 445
 446         case MP4_trkn:
 447             {
 448                 unsigned short n[2];
 449
 450                 read_mp4_tag(fd, size, (char*) &n, sizeof(n));
 451                 id3->tracknum = betoh16(n[1]);
 452             }
 453             break;
 454
 455         case MP4_extra:
 456             {
 457                 char tag_name[TAG_NAME_LENGTH];
 458                 uint32_t sub_size;
 459
 460                 /* "mean" atom */
 461                 read_uint32be(fd, &sub_size);
 462                 size -= sub_size;
 463                 lseek(fd, sub_size - 4, SEEK_CUR);
 464                 /* "name" atom */
 465                 read_uint32be(fd, &sub_size);
 466                 size -= sub_size;
 467                 lseek(fd, 8, SEEK_CUR);
 468                 sub_size -= 12;
 469
 470                 if (sub_size > sizeof(tag_name) - 1)
 471                 {
 472                     read(fd, tag_name, sizeof(tag_name) - 1);
 473                     lseek(fd, sub_size - (sizeof(tag_name) - 1), SEEK_CUR);
 474                     tag_name[sizeof(tag_name) - 1] = 0;
 475                 }
 476                 else
 477                 {
 478                     read(fd, tag_name, sub_size);
 479                     tag_name[sub_size] = 0;
 480                 }
 481
 482                 if ((strcasecmp(tag_name, "composer") == 0) && !cwrt)
 483                 {
 484                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 485                         &id3->composer);
 486                 }
 487                 else if (strcasecmp(tag_name, "iTunSMPB") == 0)
 488                 {
 489                     char value[TAG_VALUE_LENGTH];
 490                     char* value_p = value;
 491                     char* any;
 492                     unsigned int length = sizeof(value);
 493
 494                     read_mp4_tag_string(fd, size, &value_p, &length, &any);
 495                     id3->lead_trim = get_itunes_int32(value, 1);
 496                     id3->tail_trim = get_itunes_int32(value, 2);
 497                     DEBUGF("AAC: lead_trim %d, tail_trim %d\n",
 498                         id3->lead_trim, id3->tail_trim);
 499                 }
 500                 else if (strcasecmp(tag_name, "musicbrainz track id") == 0)
 501                 {
 502                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 503                         &id3->mb_track_id);
 504                 }
 505                 else if ((strcasecmp(tag_name, "album artist") == 0))
 506                 {
 507                     read_mp4_tag_string(fd, size, &buffer, &buffer_left,
 508                         &id3->albumartist);
 509                 }
 510                 else
 511                 {
 512                     char* any;
 513                     unsigned int length = read_mp4_tag_string(fd, size,
 514                         &buffer, &buffer_left, &any);
 515
 516                     if (length > 0)
 517                     {
 518                         /* Re-use the read buffer as the dest buffer... */
 519                         buffer -= length;
 520                         buffer_left += length;
 521
 522                         if (parse_replaygain(tag_name, buffer, id3,
 523                             buffer, buffer_left) > 0)
 524                         {
 525                             /* Data used, keep it. */
 526                             buffer += length;
 527                             buffer_left -= length;
 528                         }
 529                     }
 530                 }
 531             }
 532             break;
 533
 534         default:
 535             lseek(fd, size, SEEK_CUR);
 536             break;
 537         }
 538     }
 539     while ((size_left > 0) && (errno == 0));
 540
 541     return true;
 542 }
 543
 544 static bool read_mp4_container(int fd, struct mp3entry* id3,
 545                                uint32_t size_left)
 546 {
 547     uint32_t size;
 548     uint32_t type;
 549     uint32_t handler = 0;
 550     bool rc = true;
 551     bool done = false;
 552
 553     do
 554     {
 555         size_left = read_mp4_atom(fd, &size, &type, size_left);
 556
 557         /* DEBUGF("Atom: '%c%c%c%c' (0x%08lx, %lu bytes left)\n",
 558             (int) ((type >> 24) & 0xff), (int) ((type >> 16) & 0xff),
 559             (int) ((type >> 8) & 0xff), (int) (type & 0xff),
 560             type, size); */
 561
 562         switch (type)
 563         {
 564         case MP4_ftyp:
 565             {
 566                 uint32_t id;
 567
 568                 read_uint32be(fd, &id);
 569                 size -= 4;
 570
 571                 if ((id != MP4_M4A) && (id != MP4_M4B) && (id != MP4_mp42)
 572                     && (id != MP4_qt) && (id != MP4_3gp6)
 573                     && (id != MP4_isom))
 574                 {
 575                     DEBUGF("Unknown MP4 file type: '%c%c%c%c'\n",
 576                         (int)(id >> 24 & 0xff), (int)(id >> 16 & 0xff),
 577                         (int)(id >> 8 & 0xff), (int)(id & 0xff));
 578                     return false;
 579                 }
 580             }
 581             break;
 582
 583         case MP4_meta:
 584             lseek(fd, 4, SEEK_CUR);  /* Skip version */
 585             size -= 4;
 586             /* Fall through */
 587
 588         case MP4_moov:
 589         case MP4_udta:
 590         case MP4_mdia:
 591         case MP4_stbl:
 592         case MP4_trak:
 593             rc = read_mp4_container(fd, id3, size);
 594             size = 0;
 595             break;
 596
 597         case MP4_ilst:
 598             if (handler == MP4_mdir)
 599             {
 600                 rc = read_mp4_tags(fd, id3, size);
 601                 size = 0;
 602             }
 603             break;
 604
 605         case MP4_minf:
 606             if (handler == MP4_soun)
 607             {
 608                 rc = read_mp4_container(fd, id3, size);
 609                 size = 0;
 610             }
 611             break;
 612
 613         case MP4_stsd:
 614             lseek(fd, 8, SEEK_CUR);
 615             size -= 8;
 616             rc = read_mp4_container(fd, id3, size);
 617             size = 0;
 618             break;
 619
 620         case MP4_hdlr:
 621             lseek(fd, 8, SEEK_CUR);
 622             read_uint32be(fd, &handler);
 623             size -= 12;
 624             /* DEBUGF("    Handler '%c%c%c%c'\n", handler >> 24 & 0xff,
 625                 handler >> 16 & 0xff, handler >> 8 & 0xff,handler & 0xff); */
 626             break;
 627
 628         case MP4_stts:
 629             {
 630                 uint32_t entries;
 631                 unsigned int i;
 632
 633                 lseek(fd, 4, SEEK_CUR);
 634                 read_uint32be(fd, &entries);
 635                 id3->samples = 0;
 636
 637                 for (i = 0; i < entries; i++)
 638                 {
 639                     uint32_t n;
 640                     uint32_t l;
 641
 642                     read_uint32be(fd, &n);
 643                     read_uint32be(fd, &l);
 644                     id3->samples += n * l;
 645                 }
 646
 647                 size = 0;
 648             }
 649             break;
 650
 651         case MP4_mp4a:
 652         case MP4_alac:
 653             {
 654                 uint32_t frequency;
 655
 656                 id3->codectype = (type == MP4_mp4a) ? AFMT_MP4_AAC : AFMT_MP4_ALAC;
 657                 lseek(fd, 22, SEEK_CUR);
 658                 read_uint32be(fd, &frequency);
 659                 size -= 26;
 660                 id3->frequency = frequency;
 661
 662                 if (type == MP4_mp4a)
 663                 {
 664                     uint32_t subsize;
 665                     uint32_t subtype;
 666
 667                     /* Get frequency from the decoder info tag, if possible. */
 668                     lseek(fd, 2, SEEK_CUR);
 669                     /* The esds atom is a part of the mp4a atom, so ignore
 670                      * the returned size (it's already accounted for).
 671                      */
 672                     read_mp4_atom(fd, &subsize, &subtype, size);
 673                     size -= 10;
 674
 675                     if (subtype == MP4_esds)
 676                     {
 677                         read_mp4_esds(fd, id3, &size);
 678                     }
 679                 }
 680             }
 681             break;
 682
 683         case MP4_mdat:
 684             /* Some AAC files appear to contain additional empty mdat chunks.
 685                Ignore them. */
 686             if(size == 0)
 687                 break;
 688             id3->filesize = size;
 689             if(id3->samples > 0) {
 690                 /* We've already seen the moov chunk. */
 691                 done = true;
 692             }
 693             break;
 694
 695         case MP4_chpl:
 696             {
 697                 /* ADDME: add support for real chapters. Right now it's only
 698                  * used for Nero's gapless hack */
 699                 uint8_t chapters;
 700                 uint64_t timestamp;
 701
 702                 lseek(fd, 8, SEEK_CUR);
 703                 read_uint8(fd, &chapters);
 704                 size -= 9;
 705
 706                 /* the first chapter will be used as the lead_trim */
 707                 if (chapters > 0) {
 708                     read_uint64be(fd, &timestamp);
 709                     id3->lead_trim = (timestamp * id3->frequency) / 10000000;
 710                     size -= 8;
 711                 }
 712             }
 713             break;
 714
 715         default:
 716             break;
 717         }
 718
 719         /* Skip final seek. */
 720         if (!done)
 721         {
 722             lseek(fd, size, SEEK_CUR);
 723         }
 724     } while (rc && (size_left > 0) && (errno == 0) && !done);
 725
 726     return rc;
 727 }
 728
 729 bool get_mp4_metadata(int fd, struct mp3entry* id3)
 730 {
 731     id3->codectype = AFMT_UNKNOWN;
 732     id3->filesize = 0;
 733     errno = 0;
 734
 735     if (read_mp4_container(fd, id3, filesize(fd)) && (errno == 0)
 736         && (id3->samples > 0) && (id3->frequency > 0)
 737         && (id3->filesize > 0))
 738     {
 739         if (id3->codectype == AFMT_UNKNOWN)
 740         {
 741             logf("Not an ALAC or AAC file");
 742             return false;
 743         }
 744
 745         id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
 746
 747         if (id3->length <= 0)
 748         {
 749             logf("mp4 length invalid!");
 750             return false;
 751         }
 752
 753         id3->bitrate = ((int64_t) id3->filesize * 8) / id3->length;
 754         DEBUGF("MP4 bitrate %d, frequency %ld Hz, length %ld ms\n",
 755             id3->bitrate, id3->frequency, id3->length);
 756     }
 757     else
 758     {
 759         logf("MP4 metadata error");
 760         DEBUGF("MP4 metadata error. errno %d, samples %ld, frequency %ld, "
 761             "filesize %ld\n", errno, id3->samples, id3->frequency,
 762             id3->filesize);
 763         return false;
 764     }
 765
 766     return true;
 767 }