apps/metadata/speex.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 /* A simple parser to read vital metadata from an Ogg Speex file. Returns
  31  * false if metadata needed by the Speex codec couldn't be read.
  32  */
  33
  34 bool get_speex_metadata(int fd, struct mp3entry* id3)
  35 {
  36     /* An Ogg File is split into pages, each starting with the string
  37      * "OggS". Each page has a timestamp (in PCM samples) referred to as
  38      * the "granule position".
  39      *
  40      * An Ogg Speex has the following structure:
  41      * 1) Identification header (containing samplerate, numchannels, etc)
  42           Described in this page: (http://www.speex.org/manual2/node7.html)
  43      * 2) Comment header - containing the Vorbis Comments
  44      * 3) Many audio packets...
  45      */
  46
  47     /* Use the path name of the id3 structure as a temporary buffer. */
  48     unsigned char* buf = (unsigned char*)id3->path;
  49     long comment_size;
  50     long remaining = 0;
  51     long last_serial = 0;
  52     long serial, r;
  53     int segments;
  54     int i;
  55     bool eof = false;
  56
  57     if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 58) < 33))
  58     {
  59         return false;
  60     }
  61
  62     if ((memcmp(buf, "OggS", 4) != 0) || (memcmp(&buf[28], "Speex", 5) != 0))
  63     {
  64         return false;
  65     }
  66
  67     /* We need to ensure the serial number from this page is the same as the
  68      * one from the last page (since we only support a single bitstream).
  69      */
  70     serial = get_long_le(&buf[14]);
  71     if ((lseek(fd, 33, SEEK_SET) < 0)||(read(fd, buf, 58) < 4))
  72     {
  73     return false;
  74     }
  75
  76     id3->frequency = get_slong(&buf[31]);
  77     last_serial = get_long_le(&buf[27]);/*temporary, header size*/
  78     id3->bitrate = get_long_le(&buf[47]);
  79     id3->vbr = get_long_le(&buf[55]);
  80     id3->filesize = filesize(fd);
  81     /* Comments are in second Ogg page */
  82     if (lseek(fd, 28+last_serial/*(temporary for header size)*/, SEEK_SET) < 0)
  83     {
  84     return false;
  85     }
  86
  87     /* Minimum header length for Ogg pages is 27. */
  88     if (read(fd, buf, 27) < 27)
  89     {
  90     return false;
  91     }
  92
  93     if (memcmp(buf, "OggS", 4) !=0 )
  94     {
  95     return false;
  96     }
  97
  98     segments = buf[26];
  99     /* read in segment table */
 100     if (read(fd, buf, segments) < segments)
 101     {
 102     return false;
 103     }
 104
 105     /* The second packet in a vorbis stream is the comment packet. It *may*
 106      * extend beyond the second page, but usually does not. Here we find the
 107      * length of the comment packet (or the rest of the page if the comment
 108      * packet extends to the third page).
 109      */
 110     for (i = 0; i < segments; i++)
 111     {
 112         remaining += buf[i];
 113         /* The last segment of a packet is always < 255 bytes */
 114         if (buf[i] < 255)
 115         {
 116               break;
 117         }
 118     }
 119
 120     comment_size = remaining;
 121
 122     /* Failure to read the tags isn't fatal. */
 123     read_vorbis_tags(fd, id3, remaining);
 124
 125     /* We now need to search for the last page in the file - identified by
 126      * by ('O','g','g','S',0) and retrieve totalsamples.
 127      */
 128
 129     /* A page is always < 64 kB */
 130     if (lseek(fd, -(MIN(64 * 1024, id3->filesize)), SEEK_END) < 0)
 131     {
 132     return false;
 133     }
 134
 135     remaining = 0;
 136
 137     while (!eof)
 138     {
 139         r = read(fd, &buf[remaining], MAX_PATH - remaining);
 140
 141         if (r <= 0)
 142         {
 143             eof = true;
 144         }
 145         else
 146         {
 147             remaining += r;
 148         }
 149
 150         /* Inefficient (but simple) search */
 151         i = 0;
 152
 153         while (i < (remaining - 3))
 154         {
 155             if ((buf[i] == 'O') && (memcmp(&buf[i], "OggS", 4) == 0))
 156             {
 157                 if (i < (remaining - 17))
 158                 {
 159                     /* Note that this only reads the low 32 bits of a
 160                      * 64 bit value.
 161                      */
 162                      id3->samples = get_long_le(&buf[i + 6]);
 163                      last_serial = get_long_le(&buf[i + 14]);
 164
 165                     /* If this page is very small the beginning of the next
 166                      * header could be in buffer. Jump near end of this header
 167                      * and continue */
 168                     i += 27;
 169                 }
 170                 else
 171                 {
 172                     break;
 173                 }
 174             }
 175             else
 176             {
 177                 i++;
 178             }
 179         }
 180
 181         if (i < remaining)
 182         {
 183             /* Move the remaining bytes to start of buffer.
 184              * Reuse var 'segments' as it is no longer needed */
 185             segments = 0;
 186             while (i < remaining)
 187             {
 188                 buf[segments++] = buf[i++];
 189             }
 190             remaining = segments;
 191         }
 192         else
 193         {
 194             /* Discard the rest of the buffer */
 195             remaining = 0;
 196         }
 197     }
 198
 199     /* This file has mutiple vorbis bitstreams (or is corrupt). */
 200     /* FIXME we should display an error here. */
 201     if (serial != last_serial)
 202     {
 203         logf("serialno mismatch");
 204         logf("%ld", serial);
 205         logf("%ld", last_serial);
 206     return false;
 207     }
 208
 209     id3->length = (id3->samples / id3->frequency) * 1000;
 210     id3->bitrate = (((int64_t) id3->filesize - comment_size) * 8) / id3->length;
 211     return true;
 212 }