apps/metadata/ogg.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 Vorbis file.
  31  * Can also handle parsing Ogg Speex files for metadata. Returns
  32  * false if metadata needed by the codec couldn't be read.
  33  */
  34 bool get_ogg_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 Vorbis has the following structure:
  41      * 1) Identification header (containing samplerate, numchannels, etc)
  42      * 2) Comment header - containing the Vorbis Comments
  43      * 3) Setup header - containing codec setup information
  44      * 4) Many audio packets...
  45      *
  46      * An Ogg Speex has the following structure:
  47      * 1) Identification header (containing samplerate, numchannels, etc)
  48      *    Described in this page: (http://www.speex.org/manual2/node7.html)
  49      * 2) Comment header - containing the Vorbis Comments
  50      * 3) Many audio packets.
  51      */
  52
  53     /* Use the path name of the id3 structure as a temporary buffer. */
  54     unsigned char* buf = (unsigned char *)id3->path;
  55     long comment_size;
  56     long remaining = 0;
  57     long last_serial = 0;
  58     long serial, r;
  59     int segments, header_size;
  60     int i;
  61     bool eof = false;
  62
  63     /* 92 bytes is enough for both Vorbis and Speex headers */
  64     if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 92) < 92))
  65     {
  66         return false;
  67     }
  68
  69     /* All Ogg streams start with OggS */
  70     if (memcmp(buf, "OggS", 4) != 0)
  71     {
  72         return false;
  73     }
  74
  75     /* Check for format magic and then get metadata */
  76     if (memcmp(&buf[29], "vorbis", 6) == 0)
  77     {
  78         id3->codectype = AFMT_OGG_VORBIS;
  79         id3->frequency = get_long_le(&buf[40]);
  80         id3->vbr = true;
  81
  82         /* Comments are in second Ogg page (byte 58 onwards for Vorbis) */
  83         if (lseek(fd, 58, SEEK_SET) < 0)
  84         {
  85             return false;
  86         }
  87     }
  88     else if (memcmp(&buf[28], "Speex   ", 8) == 0)
  89     {
  90         id3->codectype = AFMT_SPEEX;
  91         id3->frequency = get_slong(&buf[64]);
  92         id3->vbr = get_long_le(&buf[88]);
  93
  94         header_size = get_long_le(&buf[60]);
  95
  96         /* Comments are in second Ogg page (byte 108 onwards for Speex) */
  97         if (lseek(fd, 28 + header_size, SEEK_SET) < 0)
  98         {
  99             return false;
 100         }
 101     }
 102     else
 103     {
 104         return false;
 105     }
 106
 107     id3->filesize = filesize(fd);
 108
 109     /* We need to ensure the serial number from this page is the same as the
 110      * one from the last page (since we only support a single bitstream).
 111      */
 112     serial = get_long_le(&buf[14]);
 113
 114     /* Minimum header length for Ogg pages is 27. */
 115     if (read(fd, buf, 27) < 27)
 116     {
 117         return false;
 118     }
 119
 120     if (memcmp(buf, "OggS", 4) !=0 )
 121     {
 122         return false;
 123     }
 124
 125     segments = buf[26];
 126
 127     /* read in segment table */
 128     if (read(fd, buf, segments) < segments)
 129     {
 130         return false;
 131     }
 132
 133     /* The second packet in a vorbis stream is the comment packet. It *may*
 134      * extend beyond the second page, but usually does not. Here we find the
 135      * length of the comment packet (or the rest of the page if the comment
 136      * packet extends to the third page).
 137      */
 138     for (i = 0; i < segments; i++)
 139     {
 140         remaining += buf[i];
 141
 142         /* The last segment of a packet is always < 255 bytes */
 143         if (buf[i] < 255)
 144         {
 145               break;
 146         }
 147     }
 148
 149     comment_size = remaining;
 150
 151     if (id3->codectype == AFMT_OGG_VORBIS) {
 152         /* Now read in packet header (type and id string) */
 153         if (read(fd, buf, 7) < 7)
 154         {
 155             return false;
 156         }
 157
 158         remaining -= 7;
 159
 160         /* The first byte of a packet is the packet type; comment packets are
 161          * type 3.
 162          */
 163         if (buf[0] != 3)
 164         {
 165             return false;
 166         }
 167     }
 168
 169     /* Failure to read the tags isn't fatal. */
 170     read_vorbis_tags(fd, id3, remaining);
 171
 172     /* We now need to search for the last page in the file - identified by
 173      * by ('O','g','g','S',0) and retrieve totalsamples.
 174      */
 175
 176     /* A page is always < 64 kB */
 177     if (lseek(fd, -(MIN(64 * 1024, id3->filesize)), SEEK_END) < 0)
 178     {
 179         return false;
 180     }
 181
 182     remaining = 0;
 183
 184     while (!eof)
 185     {
 186         r = read(fd, &buf[remaining], MAX_PATH - remaining);
 187
 188         if (r <= 0)
 189         {
 190             eof = true;
 191         }
 192         else
 193         {
 194             remaining += r;
 195         }
 196
 197         /* Inefficient (but simple) search */
 198         i = 0;
 199
 200         while (i < (remaining - 3))
 201         {
 202             if ((buf[i] == 'O') && (memcmp(&buf[i], "OggS", 4) == 0))
 203             {
 204                 if (i < (remaining - 17))
 205                 {
 206                     /* Note that this only reads the low 32 bits of a
 207                      * 64 bit value.
 208                      */
 209                      id3->samples = get_long_le(&buf[i + 6]);
 210                      last_serial = get_long_le(&buf[i + 14]);
 211
 212                     /* If this page is very small the beginning of the next
 213                      * header could be in buffer. Jump near end of this header
 214                      * and continue */
 215                     i += 27;
 216                 }
 217                 else
 218                 {
 219                     break;
 220                 }
 221             }
 222             else
 223             {
 224                 i++;
 225             }
 226         }
 227
 228         if (i < remaining)
 229         {
 230             /* Move the remaining bytes to start of buffer.
 231              * Reuse var 'segments' as it is no longer needed */
 232             segments = 0;
 233             while (i < remaining)
 234             {
 235                 buf[segments++] = buf[i++];
 236             }
 237             remaining = segments;
 238         }
 239         else
 240         {
 241             /* Discard the rest of the buffer */
 242             remaining = 0;
 243         }
 244     }
 245
 246     /* This file has mutiple vorbis bitstreams (or is corrupt). */
 247     /* FIXME we should display an error here. */
 248     if (serial != last_serial)
 249     {
 250         logf("serialno mismatch");
 251         logf("%ld", serial);
 252         logf("%ld", last_serial);
 253         return false;
 254     }
 255
 256     id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
 257     if (id3->length <= 0)
 258     {
 259         logf("ogg length invalid!");
 260         return false;
 261     }
 262
 263     id3->bitrate = (((int64_t) id3->filesize - comment_size) * 8) / id3->length;
 264
 265     return true;
 266 }
 267