rockbox/apps/metadata/ogg.c
Daniel Stenberg 2acc0ac542 Updated our source code header to explicitly mention that we are GPL v2 or
later. We still need to hunt down snippets used that are not. 1324 modified
files...
http://www.rockbox.org/mail/archive/rockbox-dev-archive-2008-06/0060.shtml


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17847 a1c6a512-1295-4272-9138-f99709370657
2008-06-28 18:10:04 +00:00

270 lines
7.5 KiB
C

/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2005 Dave Chapman
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#include <inttypes.h>
#include "system.h"
#include "id3.h"
#include "metadata_common.h"
#include "metadata_parsers.h"
#include "logf.h"
/* A simple parser to read vital metadata from an Ogg Vorbis file.
* Can also handle parsing Ogg Speex files for metadata. Returns
* false if metadata needed by the codec couldn't be read.
*/
bool get_ogg_metadata(int fd, struct mp3entry* id3)
{
/* An Ogg File is split into pages, each starting with the string
* "OggS". Each page has a timestamp (in PCM samples) referred to as
* the "granule position".
*
* An Ogg Vorbis has the following structure:
* 1) Identification header (containing samplerate, numchannels, etc)
* 2) Comment header - containing the Vorbis Comments
* 3) Setup header - containing codec setup information
* 4) Many audio packets...
*
* An Ogg Speex has the following structure:
* 1) Identification header (containing samplerate, numchannels, etc)
* Described in this page: (http://www.speex.org/manual2/node7.html)
* 2) Comment header - containing the Vorbis Comments
* 3) Many audio packets.
*/
/* Use the path name of the id3 structure as a temporary buffer. */
unsigned char* buf = (unsigned char *)id3->path;
long comment_size;
long remaining = 0;
long last_serial = 0;
long serial, r;
int segments, header_size;
int i;
bool eof = false;
/* 92 bytes is enough for both Vorbis and Speex headers */
if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 92) < 92))
{
return false;
}
/* All Ogg streams start with OggS */
if (memcmp(buf, "OggS", 4) != 0)
{
return false;
}
/* Check for format magic and then get metadata */
if (memcmp(&buf[29], "vorbis", 6) == 0)
{
id3->codectype = AFMT_OGG_VORBIS;
id3->frequency = get_long_le(&buf[40]);
id3->vbr = true;
/* Comments are in second Ogg page (byte 58 onwards for Vorbis) */
if (lseek(fd, 58, SEEK_SET) < 0)
{
return false;
}
}
else if (memcmp(&buf[28], "Speex ", 8) == 0)
{
id3->codectype = AFMT_SPEEX;
id3->frequency = get_slong(&buf[64]);
id3->vbr = get_long_le(&buf[88]);
header_size = get_long_le(&buf[60]);
/* Comments are in second Ogg page (byte 108 onwards for Speex) */
if (lseek(fd, 28 + header_size, SEEK_SET) < 0)
{
return false;
}
}
else
{
return false;
}
id3->filesize = filesize(fd);
/* We need to ensure the serial number from this page is the same as the
* one from the last page (since we only support a single bitstream).
*/
serial = get_long_le(&buf[14]);
/* Minimum header length for Ogg pages is 27. */
if (read(fd, buf, 27) < 27)
{
return false;
}
if (memcmp(buf, "OggS", 4) !=0 )
{
return false;
}
segments = buf[26];
/* read in segment table */
if (read(fd, buf, segments) < segments)
{
return false;
}
/* The second packet in a vorbis stream is the comment packet. It *may*
* extend beyond the second page, but usually does not. Here we find the
* length of the comment packet (or the rest of the page if the comment
* packet extends to the third page).
*/
for (i = 0; i < segments; i++)
{
remaining += buf[i];
/* The last segment of a packet is always < 255 bytes */
if (buf[i] < 255)
{
break;
}
}
comment_size = remaining;
if (id3->codectype == AFMT_OGG_VORBIS) {
/* Now read in packet header (type and id string) */
if (read(fd, buf, 7) < 7)
{
return false;
}
remaining -= 7;
/* The first byte of a packet is the packet type; comment packets are
* type 3.
*/
if (buf[0] != 3)
{
return false;
}
}
/* Failure to read the tags isn't fatal. */
read_vorbis_tags(fd, id3, remaining);
/* We now need to search for the last page in the file - identified by
* by ('O','g','g','S',0) and retrieve totalsamples.
*/
/* A page is always < 64 kB */
if (lseek(fd, -(MIN(64 * 1024, id3->filesize)), SEEK_END) < 0)
{
return false;
}
remaining = 0;
while (!eof)
{
r = read(fd, &buf[remaining], MAX_PATH - remaining);
if (r <= 0)
{
eof = true;
}
else
{
remaining += r;
}
/* Inefficient (but simple) search */
i = 0;
while (i < (remaining - 3))
{
if ((buf[i] == 'O') && (memcmp(&buf[i], "OggS", 4) == 0))
{
if (i < (remaining - 17))
{
/* Note that this only reads the low 32 bits of a
* 64 bit value.
*/
id3->samples = get_long_le(&buf[i + 6]);
last_serial = get_long_le(&buf[i + 14]);
/* If this page is very small the beginning of the next
* header could be in buffer. Jump near end of this header
* and continue */
i += 27;
}
else
{
break;
}
}
else
{
i++;
}
}
if (i < remaining)
{
/* Move the remaining bytes to start of buffer.
* Reuse var 'segments' as it is no longer needed */
segments = 0;
while (i < remaining)
{
buf[segments++] = buf[i++];
}
remaining = segments;
}
else
{
/* Discard the rest of the buffer */
remaining = 0;
}
}
/* This file has mutiple vorbis bitstreams (or is corrupt). */
/* FIXME we should display an error here. */
if (serial != last_serial)
{
logf("serialno mismatch");
logf("%ld", serial);
logf("%ld", last_serial);
return false;
}
id3->length = ((int64_t) id3->samples * 1000) / id3->frequency;
if (id3->length <= 0)
{
logf("ogg length invalid!");
return false;
}
id3->bitrate = (((int64_t) id3->filesize - comment_size) * 8) / id3->length;
return true;
}