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  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <stdlib.h>
  24 #include <ctype.h>
  25 #include <inttypes.h>
  26
  27 #include "system.h"
  28 #include "id3.h"
  29 #include "metadata_common.h"
  30 #include "metadata_parsers.h"
  31 #include "logf.h"
  32
  33 /* A simple parser to read vital metadata from an Ogg Vorbis file.
  34  * Can also handle parsing Ogg Speex files for metadata. Returns
  35  * false if metadata needed by the codec couldn't be read.
  36  */
  37 bool get_ogg_metadata(int fd, struct mp3entry* id3)
  38 {
  39     /* An Ogg File is split into pages, each starting with the string
  40      * "OggS". Each page has a timestamp (in PCM samples) referred to as
  41      * the "granule position".
  42      *
  43      * An Ogg Vorbis has the following structure:
  44      * 1) Identification header (containing samplerate, numchannels, etc)
  45      * 2) Comment header - containing the Vorbis Comments
  46      * 3) Setup header - containing codec setup information
  47      * 4) Many audio packets...
  48      *
  49      * An Ogg Speex has the following structure:
  50      * 1) Identification header (containing samplerate, numchannels, etc)
  51      *    Described in this page: (http://www.speex.org/manual2/node7.html)
  52      * 2) Comment header - containing the Vorbis Comments
  53      * 3) Many audio packets.
  54      */
  55
  56     /* Use the path name of the id3 structure as a temporary buffer. */
  57     unsigned char* buf = (unsigned char *)id3->path;
  58     long comment_size;
  59     long remaining = 0;
  60     long last_serial = 0;
  61     long serial, r;
  62     int segments, header_size;
  63     int i;
  64     bool eof = false;
  65
  66     /* 92 bytes is enough for both Vorbis and Speex headers */
  67     if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 92) < 92))
  68     {
  69         return false;
  70     }
  71
  72     /* All Ogg streams start with OggS */
  73     if (memcmp(buf, "OggS", 4) != 0)
  74     {
  75         return false;
  76     }
  77
  78     /* Check for format magic and then get metadata */
  79     if (memcmp(&buf[29], "vorbis", 6) == 0)
  80     {
  81         id3->codectype = AFMT_OGG_VORBIS;
  82         id3->frequency = get_long_le(&buf[40]);
  83         id3->vbr = true;
  84
  85         /* Comments are in second Ogg page (byte 58 onwards for Vorbis) */
  86         if (lseek(fd, 58, SEEK_SET) < 0)
  87         {
  88             return false;
  89         }
  90     }
  91     else if (memcmp(&buf[28], "Speex   ", 8) == 0)
  92     {
  93         id3->codectype = AFMT_SPEEX;
  94         id3->frequency = get_slong(&buf[64]);
  95         id3->vbr = get_long_le(&buf[88]);
  96
  97         header_size = get_long_le(&buf[60]);
  98
  99         /* Comments are in second Ogg page (byte 108 onwards for Speex) */
 100         if (lseek(fd, 28 + header_size, SEEK_SET) < 0)
 101         {
 102             return false;
 103         }
 104     }
 105     else
 106     {
 107         return false;
 108     }
 109
 110     id3->filesize = filesize(fd);
 111
 112     /* We need to ensure the serial number from this page is the same as the
 113      * one from the last page (since we only support a single bitstream).
 114      */
 115     serial = get_long_le(&buf[14]);
 116
 117     /* Minimum header length for Ogg pages is 27. */
 118     if (read(fd, buf, 27) < 27)
 119     {
 120         return false;
 121     }
 122
 123     if (memcmp(buf, "OggS", 4) !=0 )
 124     {
 125         return false;
 126     }
 127
 128     segments = buf[26];
 129
 130     /* read in segment table */
 131     if (read(fd, buf, segments) < segments)
 132     {
 133         return false;
 134     }
 135
 136     /* The second packet in a vorbis stream is the comment packet. It *may*
 137      * extend beyond the second page, but usually does not. Here we find the
 138      * length of the comment packet (or the rest of the page if the comment
 139      * packet extends to the third page).
 140      */
 141     for (i = 0; i < segments; i++)
 142     {
 143         remaining += buf[i];
 144
 145         /* The last segment of a packet is always < 255 bytes */
 146         if (buf[i] < 255)
 147         {
 148               break;
 149         }
 150     }
 151
 152     comment_size = remaining;
 153
 154     if (id3->codectype == AFMT_OGG_VORBIS) {
 155         /* Now read in packet header (type and id string) */
 156         if (read(fd, buf, 7) < 7)
 157         {
 158             return false;
 159         }
 160
 161         remaining -= 7;
 162
 163         /* The first byte of a packet is the packet type; comment packets are
 164          * type 3.
 165          */
 166         if (buf[0] != 3)
 167         {
 168             return false;
 169         }
 170     }
 171
 172     /* Failure to read the tags isn't fatal. */
 173     read_vorbis_tags(fd, id3, remaining);
 174
 175     /* We now need to search for the last page in the file - identified by
 176      * by ('O','g','g','S',0) and retrieve totalsamples.
 177      */
 178
 179     /* A page is always < 64 kB */
 180     if (lseek(fd, -(MIN(64 * 1024, id3->filesize)), SEEK_END) < 0)
 181     {
 182         return false;
 183     }
 184
 185     remaining = 0;
 186
 187     while (!eof)
 188     {
 189         r = read(fd, &buf[remaining], MAX_PATH - remaining);
 190
 191         if (r <= 0)
 192         {
 193             eof = true;
 194         }
 195         else
 196         {
 197             remaining += r;
 198         }
 199
 200         /* Inefficient (but simple) search */
 201         i = 0;
 202
 203         while (i < (remaining - 3))
 204         {
 205             if ((buf[i] == 'O') && (memcmp(&buf[i], "OggS", 4) == 0))
 206             {
 207                 if (i < (remaining - 17))
 208                 {
 209                     /* Note that this only reads the low 32 bits of a
 210                      * 64 bit value.
 211                      */
 212                      id3->samples = get_long_le(&buf[i + 6]);
 213                      last_serial = get_long_le(&buf[i + 14]);
 214
 215                     /* If this page is very small the beginning of the next
 216                      * header could be in buffer. Jump near end of this header
 217                      * and continue */
 218                     i += 27;
 219                 }
 220                 else
 221                 {
 222                     break;
 223                 }
 224             }
 225             else
 226             {
 227                 i++;
 228             }
 229         }
 230
 231         if (i < remaining)
 232         {
 233             /* Move the remaining bytes to start of buffer.
 234              * Reuse var 'segments' as it is no longer needed */
 235             segments = 0;
 236             while (i < remaining)
 237             {
 238                 buf[segments++] = buf[i++];
 239             }
 240             remaining = segments;
 241         }
 242         else
 243         {
 244             /* Discard the rest of the buffer */
 245             remaining = 0;
 246         }
 247     }
 248
 249     /* This file has mutiple vorbis bitstreams (or is corrupt). */
 250     /* FIXME we should display an error here. */
 251     if (serial != last_serial)
 252     {
 253         logf("serialno mismatch");
 254         logf("%ld", serial);
 255         logf("%ld", last_serial);
 256         return false;
 257     }
 258
 259     id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
 260     if (id3->length <= 0)
 261     {
 262         logf("ogg length invalid!");
 263         return false;
 264     }
 265
 266     id3->bitrate = (((int64_t) id3->filesize - comment_size) * 8) / id3->length;
 267
 268     return true;
 269 }
 270