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 "metadata_parsers.h"
  29 #include "logf.h"
  30
  31 /* A simple parser to read vital metadata from an Ogg Vorbis file.
  32  * Can also handle parsing Ogg Speex files for metadata. Returns
  33  * false if metadata needed by the codec couldn't be read.
  34  */
  35 bool get_ogg_metadata(int fd, struct mp3entry* id3)
  36 {
  37     /* An Ogg File is split into pages, each starting with the string
  38      * "OggS". Each page has a timestamp (in PCM samples) referred to as
  39      * the "granule position".
  40      *
  41      * An Ogg Vorbis has the following structure:
  42      * 1) Identification header (containing samplerate, numchannels, etc)
  43      * 2) Comment header - containing the Vorbis Comments
  44      * 3) Setup header - containing codec setup information
  45      * 4) Many audio packets...
  46      *
  47      * An Ogg Speex has the following structure:
  48      * 1) Identification header (containing samplerate, numchannels, etc)
  49      *    Described in this page: (http://www.speex.org/manual2/node7.html)
  50      * 2) Comment header - containing the Vorbis Comments
  51      * 3) Many audio packets.
  52      */
  53
  54     /* Use the path name of the id3 structure as a temporary buffer. */
  55     unsigned char* buf = (unsigned char *)id3->path;
  56     long comment_size;
  57     long remaining = 0;
  58     long last_serial = 0;
  59     long serial, r;
  60     int segments, header_size;
  61     int i;
  62     bool eof = false;
  63
  64     /* 92 bytes is enough for both Vorbis and Speex headers */
  65     if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 92) < 92))
  66     {
  67         return false;
  68     }
  69
  70     /* All Ogg streams start with OggS */
  71     if (memcmp(buf, "OggS", 4) != 0)
  72     {
  73         return false;
  74     }
  75
  76     /* Check for format magic and then get metadata */
  77     if (memcmp(&buf[29], "vorbis", 6) == 0)
  78     {
  79         id3->codectype = AFMT_OGG_VORBIS;
  80         id3->frequency = get_long_le(&buf[40]);
  81         id3->vbr = true;
  82
  83         /* Comments are in second Ogg page (byte 58 onwards for Vorbis) */
  84         if (lseek(fd, 58, SEEK_SET) < 0)
  85         {
  86             return false;
  87         }
  88     }
  89     else if (memcmp(&buf[28], "Speex   ", 8) == 0)
  90     {
  91         id3->codectype = AFMT_SPEEX;
  92         id3->frequency = get_slong(&buf[64]);
  93         id3->vbr = get_long_le(&buf[88]);
  94
  95         header_size = get_long_le(&buf[60]);
  96
  97         /* Comments are in second Ogg page (byte 108 onwards for Speex) */
  98         if (lseek(fd, 28 + header_size, SEEK_SET) < 0)
  99         {
 100             return false;
 101         }
 102     }
 103     else
 104     {
 105         return false;
 106     }
 107
 108     id3->filesize = filesize(fd);
 109
 110     /* We need to ensure the serial number from this page is the same as the
 111      * one from the last page (since we only support a single bitstream).
 112      */
 113     serial = get_long_le(&buf[14]);
 114
 115     /* Minimum header length for Ogg pages is 27. */
 116     if (read(fd, buf, 27) < 27)
 117     {
 118         return false;
 119     }
 120
 121     if (memcmp(buf, "OggS", 4) !=0 )
 122     {
 123         return false;
 124     }
 125
 126     segments = buf[26];
 127
 128     /* read in segment table */
 129     if (read(fd, buf, segments) < segments)
 130     {
 131         return false;
 132     }
 133
 134     /* The second packet in a vorbis stream is the comment packet. It *may*
 135      * extend beyond the second page, but usually does not. Here we find the
 136      * length of the comment packet (or the rest of the page if the comment
 137      * packet extends to the third page).
 138      */
 139     for (i = 0; i < segments; i++)
 140     {
 141         remaining += buf[i];
 142
 143         /* The last segment of a packet is always < 255 bytes */
 144         if (buf[i] < 255)
 145         {
 146               break;
 147         }
 148     }
 149
 150     comment_size = remaining;
 151
 152     if (id3->codectype == AFMT_OGG_VORBIS) {
 153         /* Now read in packet header (type and id string) */
 154         if (read(fd, buf, 7) < 7)
 155         {
 156             return false;
 157         }
 158
 159         remaining -= 7;
 160
 161         /* The first byte of a packet is the packet type; comment packets are
 162          * type 3.
 163          */
 164         if (buf[0] != 3)
 165         {
 166             return false;
 167         }
 168     }
 169
 170     /* Failure to read the tags isn't fatal. */
 171     read_vorbis_tags(fd, id3, remaining);
 172
 173     /* We now need to search for the last page in the file - identified by
 174      * by ('O','g','g','S',0) and retrieve totalsamples.
 175      */
 176
 177     /* A page is always < 64 kB */
 178     if (lseek(fd, -(MIN(64 * 1024, id3->filesize)), SEEK_END) < 0)
 179     {
 180         return false;
 181     }
 182
 183     remaining = 0;
 184
 185     while (!eof)
 186     {
 187         r = read(fd, &buf[remaining], MAX_PATH - remaining);
 188
 189         if (r <= 0)
 190         {
 191             eof = true;
 192         }
 193         else
 194         {
 195             remaining += r;
 196         }
 197
 198         /* Inefficient (but simple) search */
 199         i = 0;
 200
 201         while (i < (remaining - 3))
 202         {
 203             if ((buf[i] == 'O') && (memcmp(&buf[i], "OggS", 4) == 0))
 204             {
 205                 if (i < (remaining - 17))
 206                 {
 207                     /* Note that this only reads the low 32 bits of a
 208                      * 64 bit value.
 209                      */
 210                      id3->samples = get_long_le(&buf[i + 6]);
 211                      last_serial = get_long_le(&buf[i + 14]);
 212
 213                     /* If this page is very small the beginning of the next
 214                      * header could be in buffer. Jump near end of this header
 215                      * and continue */
 216                     i += 27;
 217                 }
 218                 else
 219                 {
 220                     break;
 221                 }
 222             }
 223             else
 224             {
 225                 i++;
 226             }
 227         }
 228
 229         if (i < remaining)
 230         {
 231             /* Move the remaining bytes to start of buffer.
 232              * Reuse var 'segments' as it is no longer needed */
 233             segments = 0;
 234             while (i < remaining)
 235             {
 236                 buf[segments++] = buf[i++];
 237             }
 238             remaining = segments;
 239         }
 240         else
 241         {
 242             /* Discard the rest of the buffer */
 243             remaining = 0;
 244         }
 245     }
 246
 247     /* This file has mutiple vorbis bitstreams (or is corrupt). */
 248     /* FIXME we should display an error here. */
 249     if (serial != last_serial)
 250     {
 251         logf("serialno mismatch");
 252         logf("%ld", serial);
 253         logf("%ld", last_serial);
 254         return false;
 255     }
 256
 257     id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
 258     if (id3->length <= 0)
 259     {
 260         logf("ogg length invalid!");
 261         return false;
 262     }
 263
 264     id3->bitrate = (((int64_t) id3->filesize - comment_size) * 8) / id3->length;
 265
 266     return true;
 267 }
 268