apps/metadata/flac.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2005 Dave Chapman
  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 "metadata.h"
  29 #include "metadata_common.h"
  30 #include "metadata_parsers.h"
  31 #include "logf.h"
  32
  33 bool get_flac_metadata(int fd, struct mp3entry* id3)
  34 {
  35     /* A simple parser to read vital metadata from a FLAC file - length,
  36      * frequency, bitrate etc. This code should either be moved to a
  37      * seperate file, or discarded in favour of the libFLAC code.
  38      * The FLAC stream specification can be found at
  39      * http://flac.sourceforge.net/format.html#stream
  40      */
  41
  42     /* Use the trackname part of the id3 structure as a temporary buffer */
  43     unsigned char* buf = (unsigned char *)id3->path;
  44     bool last_metadata = false;
  45     bool rc = false;
  46
  47     if (!skip_id3v2(fd, id3) || (read(fd, buf, 4) < 4))
  48     {
  49         return rc;
  50     }
  51
  52     if (memcmp(buf, "fLaC", 4) != 0)
  53     {
  54         return rc;
  55     }
  56
  57     while (!last_metadata)
  58     {
  59         unsigned long i;
  60         int type;
  61
  62         if (read(fd, buf, 4) < 0)
  63         {
  64             return rc;
  65         }
  66
  67         last_metadata = buf[0] & 0x80;
  68         type = buf[0] & 0x7f;
  69         /* The length of the block */
  70         i = (buf[1] << 16) | (buf[2] << 8) | buf[3];
  71
  72         if (type == 0)       /* 0 is the STREAMINFO block */
  73         {
  74             unsigned long totalsamples;
  75
  76             if (i >= sizeof(id3->path) || read(fd, buf, i) < 0)
  77             {
  78                 return rc;
  79             }
  80
  81             id3->vbr = true;   /* All FLAC files are VBR */
  82             id3->filesize = filesize(fd);
  83             id3->frequency = (buf[10] << 12) | (buf[11] << 4)
  84                 | ((buf[12] & 0xf0) >> 4);
  85             rc = true;  /* Got vital metadata */
  86
  87             /* totalsamples is a 36-bit field, but we assume <= 32 bits are used */
  88             totalsamples = get_long_be(&buf[14]);
  89
  90             /* Calculate track length (in ms) and estimate the bitrate (in kbit/s) */
  91             id3->length = ((int64_t) totalsamples * 1000) / id3->frequency;
  92
  93             if (id3->length <= 0)
  94             {
  95                 logf("flac length invalid!");
  96                 return false;
  97             }
  98
  99             id3->bitrate = (id3->filesize * 8) / id3->length;
 100         }
 101         else if (type == 4)  /* 4 is the VORBIS_COMMENT block */
 102         {
 103             /* The next i bytes of the file contain the VORBIS COMMENTS. */
 104             if (!read_vorbis_tags(fd, id3, i))
 105             {
 106                 return rc;
 107             }
 108         }
 109         else if (!last_metadata)
 110         {
 111             /* Skip to next metadata block */
 112             if (lseek(fd, i, SEEK_CUR) < 0)
 113             {
 114                 return rc;
 115             }
 116         }
 117     }
 118
 119     return true;
 120 }