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  * All files in this archive are subject to the GNU General Public License.
  13  * See the file COPYING in the source tree root for full license agreement.
  14  *
  15  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  16  * KIND, either express or implied.
  17  *
  18  ****************************************************************************/
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <ctype.h>
  23 #include <inttypes.h>
  24
  25 #include "system.h"
  26 #include "id3.h"
  27 #include "metadata_common.h"
  28 #include "logf.h"
  29
  30 bool get_flac_metadata(int fd, struct mp3entry* id3)
  31 {
  32     /* A simple parser to read vital metadata from a FLAC file - length,
  33      * frequency, bitrate etc. This code should either be moved to a
  34      * seperate file, or discarded in favour of the libFLAC code.
  35      * The FLAC stream specification can be found at
  36      * http://flac.sourceforge.net/format.html#stream
  37      */
  38
  39     /* Use the trackname part of the id3 structure as a temporary buffer */
  40     unsigned char* buf = (unsigned char *)id3->path;
  41     bool rc = false;
  42
  43     if (!skip_id3v2(fd, id3) || (read(fd, buf, 4) < 4))
  44     {
  45         return rc;
  46     }
  47
  48     if (memcmp(buf, "fLaC", 4) != 0)
  49     {
  50         return rc;
  51     }
  52
  53     while (true)
  54     {
  55         long i;
  56
  57         if (read(fd, buf, 4) < 0)
  58         {
  59             return rc;
  60         }
  61
  62         /* The length of the block */
  63         i = (buf[1] << 16) | (buf[2] << 8) | buf[3];
  64
  65         if ((buf[0] & 0x7f) == 0)       /* 0 is the STREAMINFO block */
  66         {
  67             unsigned long totalsamples;
  68
  69             /* FIXME: Don't trust the value of i */
  70             if (read(fd, buf, i) < 0)
  71             {
  72                 return rc;
  73             }
  74
  75             id3->vbr = true;   /* All FLAC files are VBR */
  76             id3->filesize = filesize(fd);
  77             id3->frequency = (buf[10] << 12) | (buf[11] << 4)
  78                 | ((buf[12] & 0xf0) >> 4);
  79             rc = true;  /* Got vital metadata */
  80
  81             /* totalsamples is a 36-bit field, but we assume <= 32 bits are used */
  82             totalsamples = get_long_be(&buf[14]);
  83
  84             /* Calculate track length (in ms) and estimate the bitrate (in kbit/s) */
  85             id3->length = ((int64_t) totalsamples * 1000) / id3->frequency;
  86
  87             if (id3->length <= 0)
  88             {
  89                 logf("flac length invalid!");
  90                 return false;
  91             }
  92
  93             id3->bitrate = (id3->filesize * 8) / id3->length;
  94         }
  95         else if ((buf[0] & 0x7f) == 4)  /* 4 is the VORBIS_COMMENT block */
  96         {
  97             /* The next i bytes of the file contain the VORBIS COMMENTS. */
  98             if (!read_vorbis_tags(fd, id3, i))
  99             {
 100                 return rc;
 101             }
 102         }
 103         else
 104         {
 105             if (buf[0] & 0x80)
 106             {
 107                 /* If we have reached the last metadata block, abort. */
 108                 break;
 109             }
 110             else
 111             {
 112                 /* Skip to next metadata block */
 113                 if (lseek(fd, i, SEEK_CUR) < 0)
 114                 {
 115                     return rc;
 116                 }
 117             }
 118         }
 119     }
 120
 121     return true;
 122 }