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rockbox/firmware/id3.c
Daniel Stenberg 3d6df952ec Added support for the unofficial MPEG version 2.5 format that uses a somewhat 
different frequency table but the same bitrate table that V2 has.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@1805 a1c6a512-1295-4272-9138-f99709370657
2002-08-19 14:15:33 +00:00

684 lines
18 KiB
C
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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2002 by Daniel Stenberg
*
* All files in this archive are subject to the GNU General Public License.
* See the file COPYING in the source tree root for full license agreement.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
/*
* Parts of this code has been stolen from the Ample project and was written
* by David Härdeman. It has since been extended and enhanced pretty much by
* all sorts of friendly Rockbox people.
*
* A nice reference for MPEG header info:
* http://rockbox.haxx.se/docs/mpeghdr.html
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdbool.h>
#include "file.h"
#include "debug.h"
#include "atoi.h"
#include "id3.h"
/* Some utility macros used in getsonglength() */
#define BYTE0(x) ((x >> 24) & 0xFF)
#define BYTE1(x) ((x >> 16) & 0xFF)
#define BYTE2(x) ((x >> 8) & 0xFF)
#define BYTE3(x) ((x >> 0) & 0xFF)
#define UNSYNC(b1,b2,b3,b4) (((b1 & 0x7F) << (3*7)) | \
((b2 & 0x7F) << (2*7)) | \
((b3 & 0x7F) << (1*7)) | \
((b4 & 0x7F) << (0*7)))
/* Table of bitrates for MP3 files, all values in kilo.
* Indexed by version, layer and value of bit 15-12 in header.
*/
const int bitrate_table[2][3][16] =
{
{
{0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,0},
{0,32,48,56, 64,80, 96, 112,128,160,192,224,256,320,384,0},
{0,32,40,48, 56,64, 80, 96, 112,128,160,192,224,256,320,0}
},
{
{0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,0},
{0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0},
{0, 8,16,24,32,40,48, 56, 64, 80, 96,112,128,144,160,0}
}
};
/* Table of samples per frame for MP3 files.
* Indexed by layer. Multiplied with 1000.
*/
const int bs[4] = {0, 384000, 1152000, 1152000};
/* Table of sample frequency for MP3 files.
* Indexed by version and layer.
*/
const int freqtab[][4] =
{
{11025, 12000, 8000, 0}, /* MPEG version 2.5 */
{44100, 48000, 32000, 0}, /* MPEG Version 1 */
{22050, 24000, 16000, 0}, /* MPEG version 2 */
};
/*
* Removes trailing spaces from a string.
*
* Arguments: buffer - the string to process
*
* Returns: void
*/
static void
stripspaces(char *buffer)
{
int i = 0;
while(*(buffer + i) != '\0')
i++;
for(;i >= 0; i--) {
if(*(buffer + i) == ' ')
*(buffer + i) = '\0';
else if(*(buffer + i) == '\0')
continue;
else
break;
}
}
/*
* Sets the title of an MP3 entry based on its ID3v1 tag.
*
* Arguments: file - the MP3 file to scen for a ID3v1 tag
* entry - the entry to set the title in
*
* Returns: true if a title was found and created, else false
*/
static bool setid3v1title(int fd, struct mp3entry *entry)
{
char buffer[31];
int offsets[3] = {-95,-65,-125};
int i;
for(i=0;i<3;i++) {
if(-1 == lseek(fd, offsets[i], SEEK_END))
return false;
buffer[30]=0;
read(fd, buffer, 30);
stripspaces(buffer);
if(buffer[0]) {
switch(i) {
case 0:
strcpy(entry->id3v1buf[0], buffer);
entry->artist = entry->id3v1buf[0];
break;
case 1:
strcpy(entry->id3v1buf[1], buffer);
entry->album = entry->id3v1buf[1];
break;
case 2:
strcpy(entry->id3v1buf[2], buffer);
entry->title = entry->id3v1buf[2];
break;
}
}
}
return true;
}
/*
* Sets the title of an MP3 entry based on its ID3v2 tag.
*
* Arguments: file - the MP3 file to scen for a ID3v2 tag
* entry - the entry to set the title in
*
* Returns: true if a title was found and created, else false
*/
static void setid3v2title(int fd, struct mp3entry *entry)
{
unsigned int minframesize;
int size;
unsigned int readsize = 0, headerlen;
char *title = NULL;
char *artist = NULL;
char *album = NULL;
char *tracknum = NULL;
char header[10];
unsigned short int version;
int titlen=0, artistn=0, albumn=0, tracknumn=0;
char *buffer = entry->id3v2buf;
/* 10 = headerlength */
if(entry->id3v2len < 10)
return;
/* Check version */
lseek(fd, 0, SEEK_SET);
if(10 != read(fd, header, 10))
return;
version = (unsigned short int)header[3];
/* Read all frames in the tag */
size = entry->id3v2len - 10;
if(size >= (int)sizeof(entry->id3v2buf))
size = sizeof(entry->id3v2buf)-1;
if(size != read(fd, buffer, size))
return;
*(buffer + size) = '\0';
/* Set minimun frame size according to ID3v2 version */
if(version > 2)
minframesize = 12;
else
minframesize = 8;
/*
* We must have at least minframesize bytes left for the
* remaining frames to be interesting
*/
while(size - readsize > minframesize) {
/* Read frame header and check length */
if(version > 2) {
memcpy(header, (buffer + readsize), 10);
readsize += 10;
headerlen = UNSYNC(header[4], header[5],
header[6], header[7]);
} else {
memcpy(header, (buffer + readsize), 6);
readsize += 6;
headerlen = (header[3] << 16) +
(header[4] << 8) +
(header[5]);
}
if(headerlen < 1)
continue;
/* Check for certain frame headers */
if(!strncmp(header, "TPE1", strlen("TPE1")) ||
!strncmp(header, "TP1", strlen("TP1"))) {
readsize++;
headerlen--;
if(headerlen > (size - readsize))
headerlen = (size - readsize);
artist = buffer + readsize;
artistn = headerlen;
readsize += headerlen;
}
else if(!strncmp(header, "TIT2", strlen("TIT2")) ||
!strncmp(header, "TT2", strlen("TT2"))) {
readsize++;
headerlen--;
if(headerlen > (size - readsize))
headerlen = (size - readsize);
title = buffer + readsize;
titlen = headerlen;
readsize += headerlen;
}
else if(!strncmp(header, "TALB", strlen("TALB"))) {
readsize++;
headerlen--;
if(headerlen > (size - readsize))
headerlen = (size - readsize);
album = buffer + readsize;
albumn = headerlen;
readsize += headerlen;
}
else if(!strncmp(header, "TRCK", strlen("TRCK"))) {
readsize++;
headerlen--;
if(headerlen > (size - readsize))
headerlen = (size - readsize);
tracknum = buffer + readsize;
tracknumn = headerlen;
readsize += headerlen;
} else {
readsize += headerlen;
}
}
if(artist) {
entry->artist = artist;
artist[artistn]=0;
}
if(title) {
entry->title = title;
title[titlen]=0;
}
if(album) {
entry->album = album;
album[albumn]=0;
}
if(tracknum) {
tracknum[tracknumn] = 0;
entry->tracknum = atoi(tracknum);
}
}
/*
* Calculates the size of the ID3v2 tag.
*
* Arguments: file - the file to search for a tag.
*
* Returns: the size of the tag or 0 if none was found
*/
static int getid3v2len(int fd)
{
char buf[6];
int offset;
/* Make sure file has a ID3 tag */
if((-1 == lseek(fd, 0, SEEK_SET)) ||
(read(fd, buf, 6) != 6) ||
(strncmp(buf, "ID3", strlen("ID3")) != 0))
offset = 0;
/* Now check what the ID3v2 size field says */
else if(read(fd, buf, 4) != 4)
offset = 0;
else
offset = UNSYNC(buf[0], buf[1], buf[2], buf[3]) + 10;
return offset;
}
static int getfilesize(int fd)
{
int size;
/* seek to the end of it */
size = lseek(fd, 0, SEEK_END);
if(-1 == size)
return 0; /* unknown */
return size;
}
/*
* Calculates the size of the ID3v1 tag.
*
* Arguments: file - the file to search for a tag.
*
* Returns: the size of the tag or 0 if none was found
*/
static int getid3v1len(int fd)
{
char buf[3];
int offset;
/* Check if we find "TAG" 128 bytes from EOF */
if((lseek(fd, -128, SEEK_END) == -1) ||
(read(fd, buf, 3) != 3) ||
(strncmp(buf, "TAG", 3) != 0))
offset = 0;
else
offset = 128;
return offset;
}
/* check if 'head' is a valid mp3 frame header */
static bool mp3frameheader(unsigned long head)
{
if ((head & 0xffe00000) != 0xffe00000) /* bad sync? */
return false;
if (!((head >> 17) & 3)) /* no layer? */
return false;
if (((head >> 12) & 0xf) == 0xf) /* bad bitrate? */
return false;
if (!((head >> 12) & 0xf)) /* no bitrate? */
return false;
if (((head >> 10) & 0x3) == 0x3) /* bad sample rate? */
return false;
if (((head >> 19) & 1) == 1 &&
((head >> 17) & 3) == 3 &&
((head >> 16) & 1) == 1)
return false;
if ((head & 0xffff0000) == 0xfffe0000)
return false;
return true;
}
/*
* Calculates the length (in milliseconds) of an MP3 file.
*
* Modified to only use integers.
*
* Arguments: file - the file to calculate the length upon
* entry - the entry to update with the length
*
* Returns: the song length in milliseconds,
* -1 means that it couldn't be calculated
*/
static int getsonglength(int fd, struct mp3entry *entry)
{
unsigned int filetime = 0;
unsigned long header=0;
unsigned char tmp;
unsigned char frame[156];
unsigned char* xing;
enum {
MPEG_VERSION2_5,
MPEG_VERSION1,
MPEG_VERSION2
} version;
int layer;
int bitindex;
int bitrate;
int freqindex;
int frequency;
int chmode;
int bytecount;
int bittable; /* which bitrate table to use */
long bpf;
long tpf;
/* Start searching after ID3v2 header */
if(-1 == lseek(fd, entry->id3v2len, SEEK_SET))
return -1;
/* Fill up header with first 24 bits */
for(version = 0; version < 3; version++) {
header <<= 8;
if(!read(fd, &tmp, 1))
return -1;
header |= tmp;
}
/* Loop trough file until we find a frame header */
bytecount = 0;
restart:
do {
header <<= 8;
if(!read(fd, &tmp, 1))
return -1;
header |= tmp;
/* Quit if we haven't found a valid header within 128K */
bytecount++;
if(bytecount > 0x20000)
return -1;
} while(!mp3frameheader(header));
/*
* Some files are filled with garbage in the beginning,
* if the bitrate index of the header is binary 1111
* that is a good indicator
*/
if((header & 0xF000) == 0xF000)
goto restart;
#ifdef DEBUG_VERBOSE
fprintf(stderr,
"We found %x-%x-%x-%x and checksync %i and test %x\n",
BYTE0(header), BYTE1(header), BYTE2(header), BYTE3(header),
CHECKSYNC(header), (header & 0xF000) == 0xF000);
#endif
/* MPEG Audio Version */
switch((header & 0x180000) >> 19) {
case 0:
/* MPEG version 2.5 is not an official standard */
version = MPEG_VERSION2_5;
bittable = MPEG_VERSION2; /* use the V2 bit rate table */
break;
case 2:
/* MPEG version 2 (ISO/IEC 13818-3) */
version = MPEG_VERSION2;
bittable = MPEG_VERSION2;
break;
case 3:
/* MPEG version 1 (ISO/IEC 11172-3) */
version = MPEG_VERSION1;
bittable = MPEG_VERSION1;
break;
default:
goto restart;
}
/* Layer */
switch((header & 0x060000) >> 17) {
case 1:
layer = 3;
break;
case 2:
layer = 2;
break;
case 3:
layer = 1;
break;
default:
goto restart;
}
/* Bitrate */
bitindex = (header & 0xF000) >> 12;
bitrate = bitrate_table[bittable-1][layer-1][bitindex];
if(bitrate == 0)
goto restart;
/* Sampling frequency */
freqindex = (header & 0x0C00) >> 10;
frequency = freqtab[version][freqindex];
if(frequency == 0)
goto restart;
#ifdef DEBUG_VERBOSE
DEBUGF( "Version %i, lay %i, biti %i, bitr %i, freqi %i, freq %i, chmode %d\n",
version, layer, bitindex, bitrate, freqindex, frequency, chmode);
#endif
entry->version = version;
entry->layer = layer;
entry->frequency = frequency;
/* Calculate bytes per frame, calculation depends on layer */
switch(layer) {
case 1:
bpf = bitrate_table[bittable - 1][layer - 1][bitindex];
bpf *= 48000;
bpf /= freqtab[version][freqindex] << (bittable - 1);
break;
case 2:
case 3:
bpf = bitrate_table[bittable - 1][layer - 1][bitindex];
bpf *= 144000;
bpf /= freqtab[version][freqindex] << (bittable - 1);
break;
default:
bpf = 1;
}
/* Calculate time per frame */
tpf = bs[layer] / (freqtab[version][freqindex] << (bittable - 1));
entry->bpf = bpf;
entry->tpf = tpf;
/* OK, we have found a frame. Let's see if it has a Xing header */
if(read(fd, frame, sizeof frame) < 0)
return -1;
/* Channel mode (stereo/mono) */
chmode = (header & 0xc0) >> 6;
/* calculate position of Xing VBR header */
if ( version == 1 ) {
if ( chmode == 3 ) /* mono */
xing = frame + 17;
else
xing = frame + 32;
}
else {
if ( chmode == 3 ) /* mono */
xing = frame + 9;
else
xing = frame + 17;
}
if (xing[0] == 'X' &&
xing[1] == 'i' &&
xing[2] == 'n' &&
xing[3] == 'g')
{
/* Yes, it is a VBR file */
entry->vbr = true;
entry->vbrflags = xing[7];
if (entry->vbrflags & VBR_FRAMES_FLAG) /* Is the frame count there? */
{
int framecount = (xing[8] << 24) | (xing[9] << 16) |
(xing[10] << 8) | xing[11];
filetime = framecount * tpf;
}
if (entry->vbrflags & VBR_BYTES_FLAG) /* is byte count there? */
{
int bytecount = (xing[12] << 24) | (xing[13] << 16) |
(xing[14] << 8) | xing[15];
bitrate = bytecount * 8 / filetime;
}
if (entry->vbrflags & VBR_TOC_FLAG) /* is table-of-contents there? */
{
memcpy( entry->toc, xing+16, 100 );
}
}
entry->bitrate = bitrate;
/* If the file time hasn't been established, this may be a fixed
rate MP3, so just use the default formula */
if(filetime == 0)
{
/*
* Now song length is
* ((filesize)/(bytes per frame))*(time per frame)
*/
filetime = entry->filesize/bpf*tpf;
}
return filetime;
}
/*
* Checks all relevant information (such as ID3v1 tag, ID3v2 tag, length etc)
* about an MP3 file and updates it's entry accordingly.
*
* Arguments: entry - the entry to check and update with the new information
*
* Returns: void
*/
bool mp3info(struct mp3entry *entry, char *filename)
{
int fd;
fd = open(filename, O_RDONLY);
if(-1 == fd)
return true;
memset(entry, 0, sizeof(struct mp3entry));
strncpy(entry->path, filename, sizeof(entry->path));
entry->title = NULL;
entry->filesize = getfilesize(fd);
entry->id3v2len = getid3v2len(fd);
entry->tracknum = 0;
if ( entry->id3v2len && entry->id3v2len <= sizeof( entry->id3v2buf ) )
setid3v2title(fd, entry);
entry->length = getsonglength(fd, entry);
entry->id3v1len = getid3v1len(fd);
if(entry->id3v1len && !entry->title)
setid3v1title(fd, entry);
close(fd);
return false;
}
#ifdef DEBUG_STANDALONE
char *secs2str(int ms)
{
static char buffer[32];
int secs = ms/1000;
ms %= 1000;
snprintf(buffer, sizeof(buffer), "%d:%02d.%d", secs/60, secs%60, ms/100);
return buffer;
}
int main(int argc, char **argv)
{
int i;
for(i=1; i<argc; i++) {
struct mp3entry mp3;
if(mp3info(&mp3, argv[i])) {
printf("Failed to get %s\n", argv[i]);
return 0;
}
printf("****** File: %s\n"
" Title: %s\n"
" Artist: %s\n"
" Album: %s\n"
" Length: %s / %d s\n"
" Bitrate: %d\n"
" Frequency: %d\n",
argv[i],
mp3.title?mp3.title:"<blank>",
mp3.artist?mp3.artist:"<blank>",
mp3.album?mp3.album:"<blank>",
secs2str(mp3.length),
mp3.length/1000,
mp3.bitrate,
mp3.frequency);
}
return 0;
}
#endif
/* -----------------------------------------------------------------
* local variables:
* eval: (load-file "rockbox-mode.el")
* end:
*/
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