rockbox/apps/metadata/a52.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

102 lines
3.1 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 "id3.h"
#include "logf.h"
#include "metadata_parsers.h"
static const unsigned short a52_bitrates[] =
{
32, 40, 48, 56, 64, 80, 96, 112, 128, 160,
192, 224, 256, 320, 384, 448, 512, 576, 640
};
/* Only store frame sizes for 44.1KHz - others are simply multiples
of the bitrate */
static const unsigned short a52_441framesizes[] =
{
69 * 2, 70 * 2, 87 * 2, 88 * 2, 104 * 2, 105 * 2, 121 * 2,
122 * 2, 139 * 2, 140 * 2, 174 * 2, 175 * 2, 208 * 2, 209 * 2,
243 * 2, 244 * 2, 278 * 2, 279 * 2, 348 * 2, 349 * 2, 417 * 2,
418 * 2, 487 * 2, 488 * 2, 557 * 2, 558 * 2, 696 * 2, 697 * 2,
835 * 2, 836 * 2, 975 * 2, 976 * 2, 1114 * 2, 1115 * 2, 1253 * 2,
1254 * 2, 1393 * 2, 1394 * 2
};
bool get_a52_metadata(int fd, struct mp3entry *id3)
{
/* Use the trackname part of the id3 structure as a temporary buffer */
unsigned char* buf = (unsigned char *)id3->path;
unsigned long totalsamples;
int i;
if ((lseek(fd, 0, SEEK_SET) < 0) || (read(fd, buf, 5) < 5))
{
return false;
}
if ((buf[0] != 0x0b) || (buf[1] != 0x77))
{
logf("not an A52/AC3 file\n");
return false;
}
i = buf[4] & 0x3e;
if (i > 36)
{
logf("A52: Invalid frmsizecod: %d\n",i);
return false;
}
id3->bitrate = a52_bitrates[i >> 1];
id3->vbr = false;
id3->filesize = filesize(fd);
switch (buf[4] & 0xc0)
{
case 0x00:
id3->frequency = 48000;
id3->bytesperframe=id3->bitrate * 2 * 2;
break;
case 0x40:
id3->frequency = 44100;
id3->bytesperframe = a52_441framesizes[i];
break;
case 0x80:
id3->frequency = 32000;
id3->bytesperframe = id3->bitrate * 3 * 2;
break;
default:
logf("A52: Invalid samplerate code: 0x%02x\n", buf[4] & 0xc0);
return false;
break;
}
/* One A52 frame contains 6 blocks, each containing 256 samples */
totalsamples = id3->filesize / id3->bytesperframe * 6 * 256;
id3->length = totalsamples / id3->frequency * 1000;
return true;
}