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