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/*
This file is part of libextractor.
(C) 2002, 2003, 2004, 2006, 2009 Vidyut Samanta and Christian Grothoff
libextractor 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, or (at your
option) any later version.
libextractor is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with libextractor; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
Some of this code is based on AVInfo 1.0 alpha 11
(c) George Shuklin, gs]AT[shounen.ru, 2002-2004
http://shounen.ru/soft/avinfo/
*/
#define DEBUG_EXTRACT_MP3 0
#include "platform.h"
#include "extractor.h"
#include "convert.h"
#include <string.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#define MAX_MP3_SCAN_DEEP 16768
const int max_frames_scan = 1024;
enum
{ MPEG_ERR = 0, MPEG_V1 = 1, MPEG_V2 = 2, MPEG_V25 = 3 };
enum
{ LAYER_ERR = 0, LAYER_1 = 1, LAYER_2 = 2, LAYER_3 = 3 };
#define MPA_SYNC_MASK ((unsigned int) 0xFFE00000)
#define MPA_LAST_SYNC_BIT_MASK ((unsigned int) 0x00100000)
#define MPA_VERSION_MASK ((unsigned int) 0x00080000)
#define MPA_LAYER_MASK ((unsigned int) 0x3)
#define MPA_LAYER_SHIFT 17
#define MPA_BITRATE_MASK ((unsigned int) 0xF)
#define MPA_BITRATE_SHIFT 12
#define MPA_FREQ_MASK ((unsigned int) 0x3)
#define MPA_FREQ_SHIFT 10
#define MPA_CHMODE_MASK ((unsigned int) 0x3)
#define MPA_CHMODE_SHIFT 6
#define MPA_PADDING_SHIFT 9
#define MPA_COPYRIGHT_SHIFT 3
#define MPA_ORIGINAL_SHIFT 2
static const unsigned int bitrate_table[16][6] = {
{0, 0, 0, 0, 0, 0},
{32, 32, 32, 32, 8, 8},
{64, 48, 40, 48, 16, 16},
{96, 56, 48, 56, 24, 24},
{128, 64, 56, 64, 32, 32},
{160, 80, 64, 80, 40, 40},
{192, 96, 80, 96, 48, 48},
{224, 112, 96, 112, 56, 56},
{256, 128, 112, 128, 64, 64},
{288, 160, 128, 144, 80, 80},
{320, 192, 160, 160, 96, 96},
{352, 224, 192, 176, 112, 112},
{384, 256, 224, 192, 128, 128},
{416, 320, 256, 224, 144, 144},
{448, 384, 320, 256, 160, 160},
{-1, -1, -1, -1, -1, -1}
};
static const int freq_table[4][3] = {
{44100, 22050, 11025},
{48000, 24000, 12000},
{32000, 16000, 8000}
};
static const char * const channel_modes[4] = {
gettext_noop("stereo"),
gettext_noop("joint stereo"),
gettext_noop("dual channel"),
gettext_noop("mono")
};
static const char * const mpeg_versions[3] = {
gettext_noop("MPEG-1"),
gettext_noop("MPEG-2"),
gettext_noop("MPEG-2.5")
};
static const char * const layer_names[3] = {
gettext_noop("Layer I"),
gettext_noop("Layer II"),
gettext_noop("Layer III")
};
#define OK 0
#define SYSERR 1
#define INVALID_ID3 2
#define ADDR(s,t) do { if (0 != proc (proc_cls, "mp3", t, EXTRACTOR_METAFORMAT_UTF8, "text/plain", s, strlen(s)+1)) return 1; } while (0)
/* mimetype = audio/mpeg */
int
EXTRACTOR_mp3_extract (const unsigned char *data,
size_t size,
EXTRACTOR_MetaDataProcessor proc,
void *proc_cls,
const char *options)
{
unsigned int header;
int counter = 0;
char mpeg_ver = 0;
char layer = 0;
int idx_num = 0;
int bitrate = 0; /*used for each frame */
int avg_bps = 0; /*average bitrate */
int vbr_flag = 0;
int copyright_flag = 0;
int original_flag = 0;
int length = 0;
int sample_rate = 0;
int ch = 0;
int frame_size;
int frames = 0;
size_t pos = 0;
char format[512];
do
{
/* seek for frame start */
if (pos + sizeof (header) > size)
{
return 0;
} /*unable to find header */
header = (data[pos] << 24) | (data[pos+1] << 16) |
(data[pos+2] << 8) | data[pos+3];
if ((header & MPA_SYNC_MASK) == MPA_SYNC_MASK)
break; /*found header sync */
pos++;
counter++; /*next try */
}
while (counter < MAX_MP3_SCAN_DEEP);
if (counter >= MAX_MP3_SCAN_DEEP)
return 0;
ADDR ("audio/mpeg", EXTRACTOR_METATYPE_MIMETYPE);
do
{ /*ok, now we found a mp3 frame header */
frames++;
switch (header & (MPA_LAST_SYNC_BIT_MASK | MPA_VERSION_MASK))
{
case (MPA_LAST_SYNC_BIT_MASK | MPA_VERSION_MASK):
mpeg_ver = MPEG_V1;
break;
case (MPA_LAST_SYNC_BIT_MASK):
mpeg_ver = MPEG_V2;
break;
case 0:
mpeg_ver = MPEG_V25;
break;
case (MPA_VERSION_MASK):
default:
mpeg_ver = MPEG_ERR; /*error */
break;
}
switch (header & (MPA_LAYER_MASK << MPA_LAYER_SHIFT))
{
case (0x1 << MPA_LAYER_SHIFT):
layer = LAYER_3;
break;
case (0x2 << MPA_LAYER_SHIFT):
layer = LAYER_2;
break;
case (0x3 << MPA_LAYER_SHIFT):
layer = LAYER_1;
break;
case 0x0:
default:
layer = LAYER_ERR; /*error */
}
if (!layer || !mpeg_ver)
return 0; /*unknown mpeg type */
if (mpeg_ver < MPEG_V25)
idx_num = (mpeg_ver - 1) * 3 + layer - 1;
else
idx_num = 2 + layer;
bitrate = 1000 * bitrate_table[(header >> MPA_BITRATE_SHIFT) &
MPA_BITRATE_MASK][idx_num];
if (bitrate < 0)
{
frames--;
break;
} /*error in header */
sample_rate = freq_table[(header >> MPA_FREQ_SHIFT) &
MPA_FREQ_MASK][mpeg_ver - 1];
if (sample_rate < 0)
{
frames--;
break;
} /*error in header */
ch = ((header >> MPA_CHMODE_SHIFT) & MPA_CHMODE_MASK);
copyright_flag = (header >> MPA_COPYRIGHT_SHIFT) & 0x1;
original_flag = (header >> MPA_ORIGINAL_SHIFT) & 0x1;
frame_size =
144 * bitrate / (sample_rate ? sample_rate : 1) +
((header >> MPA_PADDING_SHIFT) & 0x1);
avg_bps += bitrate / 1000;
pos += frame_size - 4;
if (frames > max_frames_scan)
break; /*optimization */
if (avg_bps / frames != bitrate / 1000)
vbr_flag = 1;
if (pos + sizeof (header) > size)
break; /* EOF */
header = (data[pos] << 24) | (data[pos+1] << 16) |
(data[pos+2] << 8) | data[pos+3];
}
while ((header & MPA_SYNC_MASK) == MPA_SYNC_MASK);
if (!frames)
return 0; /*no valid frames */
avg_bps = avg_bps / frames;
if (max_frames_scan)
{ /*if not all frames scaned */
length =
size / (avg_bps ? avg_bps : bitrate ? bitrate : 0xFFFFFFFF) / 125;
}
else
{
length = 1152 * frames / (sample_rate ? sample_rate : 0xFFFFFFFF);
}
ADDR (mpeg_versions[mpeg_ver-1], EXTRACTOR_METATYPE_FORMAT_VERSION);
snprintf (format,
sizeof(format),
"%s %s audio, %d kbps (%s), %d Hz, %s, %s, %s",
mpeg_versions[mpeg_ver-1],
layer_names[layer-1],
avg_bps,
vbr_flag ? _("VBR") : _("CBR"),
sample_rate,
channel_modes[ch],
copyright_flag ? _("copyright") : _("no copyright"),
original_flag ? _("original") : _("copy") );
ADDR (format, EXTRACTOR_METATYPE_RESOURCE_TYPE);
snprintf (format,
sizeof (format), "%dm%02d",
length / 60, length % 60);
ADDR (format, EXTRACTOR_METATYPE_DURATION);
return 0;
}
/* end of mp3_extractor.c */
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