ref: 0a1bab10da12e537aab4b7ea9679d7dc54a559c8
dir: libtags/id3v2.c
/*
* Have fun reading the following:
*
* http://id3.org/id3v2.4.0-structure
* http://id3.org/id3v2.4.0-frames
* http://id3.org/d3v2.3.0
* http://id3.org/id3v2-00
* http://mpgedit.org/mpgedit/mpeg_format/mpeghdr.htm
* http://wiki.hydrogenaud.io/index.php?title=MP3#VBRI.2C_XING.2C_and_LAME_headers
* http://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header#VBRIHeader
*/
#include "tagspriv.h"
#define synchsafe(d) (uint)(((d)[0]&127)<<21 | ((d)[1]&127)<<14 | ((d)[2]&127)<<7 | ((d)[3]&127)<<0)
static int
v2cb(Tagctx *ctx, char *k, char *v)
{
k++;
if(strcmp(k, "AL") == 0 || strcmp(k, "ALB") == 0)
txtcb(ctx, Talbum, k-1, v);
else if(strcmp(k, "PE1") == 0 || strcmp(k, "PE2") == 0 || strcmp(k, "P1") == 0 || strcmp(k, "P2") == 0)
txtcb(ctx, Tartist, k-1, v);
else if(strcmp(k, "IT2") == 0 || strcmp(k, "T2") == 0)
txtcb(ctx, Ttitle, k-1, v);
else if(strcmp(k, "YE") == 0 || strcmp(k, "YER") == 0 || strcmp(k, "DRC") == 0)
txtcb(ctx, Tdate, k-1, v);
else if(strcmp(k, "RK") == 0 || strcmp(k, "RCK") == 0)
txtcb(ctx, Ttrack, k-1, v);
else if(strcmp(k, "CO") == 0 || strcmp(k, "CON") == 0){
for(; v[0]; v++){
if(v[0] == '(' && v[1] <= '9' && v[1] >= '0'){
int i = atoi(&v[1]);
if(i < Numgenre)
txtcb(ctx, Tgenre, k-1, id3genres[i]);
for(v++; v[0] && v[0] != ')'; v++);
v--;
}else if(v[0] != '(' && v[0] != ')'){
txtcb(ctx, Tgenre, k-1, v);
break;
}
}
}else if(strcmp(k, "XXX") == 0 && strncmp(v, "REPLAYGAIN_", 11) == 0){
int type = -1;
v += 11;
if(strncmp(v, "TRACK_", 6) == 0){
v += 6;
if(strcmp(v, "GAIN") == 0)
type = Ttrackgain;
else if(strcmp(v, "PEAK") == 0)
type = Ttrackpeak;
}else if(strncmp(v, "ALBUM_", 6) == 0){
v += 6;
if(strcmp(v, "GAIN") == 0)
type = Talbumgain;
else if(strcmp(v, "PEAK") == 0)
type = Talbumpeak;
}
if(type >= 0)
txtcb(ctx, type, k-1, v+5);
else
return 0;
}else{
txtcb(ctx, Tunknown, k-1, v);
}
return 1;
}
static int
rva2(Tagctx *ctx, char *tag, int sz)
{
uchar *b, *end;
if((b = memchr(tag, 0, sz)) == nil)
return -1;
b++;
for(end = (uchar*)tag+sz; b+4 < end; b += 5){
int type = b[0];
float peak;
float va = (float)(b[1]<<8 | b[2]) / 512.0f;
if(b[3] == 24){
peak = (float)(b[4]<<16 | b[5]<<8 | b[6]) / 32768.0f;
b += 2;
}else if(b[3] == 16){
peak = (float)(b[4]<<8 | b[5]) / 32768.0f;
b += 1;
}else if(b[3] == 8){
peak = (float)b[4] / 32768.0f;
}else
return -1;
if(type == 1){ /* master volume */
char vas[16], peaks[8];
snprint(vas, sizeof(vas), "%+.5f dB", va);
snprint(peaks, sizeof(peaks), "%.5f", peak);
vas[sizeof(vas)-1] = 0;
peaks[sizeof(peaks)-1] = 0;
if(strcmp((char*)tag, "track") == 0){
txtcb(ctx, Ttrackgain, "RVA2", vas);
txtcb(ctx, Ttrackpeak, "RVA2", peaks);
}else if(strcmp((char*)tag, "album") == 0){
txtcb(ctx, Talbumgain, "RVA2", vas);
txtcb(ctx, Talbumpeak, "RVA2", peaks);
}
break;
}
}
return 0;
}
static int
resync(uchar *b, int sz)
{
int i;
if(sz < 4)
return sz;
for(i = 0; i < sz-2; i++){
if(b[i] == 0xff && b[i+1] == 0x00 && (b[i+2] & 0xe0) == 0xe0){
memmove(&b[i+1], &b[i+2], sz-i-2);
sz--;
}
}
return sz;
}
static int
unsyncread(void *buf, int *sz)
{
int i;
uchar *b;
b = buf;
for(i = 0; i < *sz; i++){
if(b[i] == 0xff){
if(i+1 >= *sz || (b[i+1] == 0x00 && i+2 >= *sz))
break;
if(b[i+1] == 0x00 && (b[i+2] & 0xe0) == 0xe0){
memmove(&b[i+1], &b[i+2], *sz-i-2);
(*sz)--;
}
}
}
return i;
}
static int
nontext(Tagctx *ctx, uchar *d, int tsz, int unsync)
{
int n, offset;
char *b, *tag;
Tagread f;
tag = ctx->buf;
n = 0;
f = unsync ? unsyncread : nil;
if(strcmp((char*)d, "APIC") == 0){
offset = ctx->seek(ctx, 0, 1);
if((n = ctx->read(ctx, tag, 256)) == 256){ /* APIC mime and description should fit */
b = tag + 1; /* mime type */
for(n = 1 + strlen(b) + 2; n < 253; n++){
if(tag[0] == 0 || tag[0] == 3){ /* one zero byte */
if(tag[n] == 0){
n++;
break;
}
}else if(tag[n] == 0 && tag[n+1] == 0 && tag[n+2] == 0){
n += 3;
break;
}
}
tagscallcb(ctx, Timage, "APIC", b, offset+n, tsz-n, f);
n = 256;
}
}else if(strcmp((char*)d, "PIC") == 0){
offset = ctx->seek(ctx, 0, 1);
if((n = ctx->read(ctx, tag, 256)) == 256){ /* PIC description should fit */
b = tag + 1; /* mime type */
for(n = 5; n < 253; n++){
if(tag[0] == 0 || tag[0] == 3){ /* one zero byte */
if(tag[n] == 0){
n++;
break;
}
}else if(tag[n] == 0 && tag[n+1] == 0 && tag[n+2] == 0){
n += 3;
break;
}
}
tagscallcb(ctx, Timage, "PIC", strcmp(b, "JPG") == 0 ? "image/jpeg" : "image/png", offset+n, tsz-n, f);
n = 256;
}
}else if(strcmp((char*)d, "RVA2") == 0 && tsz >= 6+5){
/* replay gain. 6 = "track\0", 5 = other */
if(ctx->bufsz >= tsz && (n = ctx->read(ctx, tag, tsz)) == tsz)
rva2(ctx, tag, unsync ? resync((uchar*)tag, n) : n);
}
return ctx->seek(ctx, tsz-n, 1) < 0 ? -1 : 0;
}
static int
text(Tagctx *ctx, uchar *d, int tsz, int unsync)
{
char *b, *tag;
if(ctx->bufsz >= tsz+1){
/* place the data at the end to make best effort at charset conversion */
tag = &ctx->buf[ctx->bufsz - tsz - 1];
if(ctx->read(ctx, tag, tsz) != tsz)
return -1;
}else{
ctx->seek(ctx, tsz, 1);
return 0;
}
if(unsync)
tsz = resync((uchar*)tag, tsz);
tag[tsz] = 0;
b = &tag[1];
switch(tag[0]){
case 0: /* iso-8859-1 */
if(iso88591toutf8((uchar*)ctx->buf, ctx->bufsz, (uchar*)b, tsz) > 0)
v2cb(ctx, (char*)d, ctx->buf);
break;
case 1: /* utf-16 */
case 2:
if(utf16to8((uchar*)ctx->buf, ctx->bufsz, (uchar*)b, tsz) > 0)
v2cb(ctx, (char*)d, ctx->buf);
break;
case 3: /* utf-8 */
if(*b)
v2cb(ctx, (char*)d, b);
break;
}
return 0;
}
static int
isid3(uchar *d)
{
/* "ID3" version[2] flags[1] size[4] */
return (
d[0] == 'I' && d[1] == 'D' && d[2] == '3' &&
d[3] < 0xff && d[4] < 0xff &&
d[6] < 0x80 && d[7] < 0x80 && d[8] < 0x80 && d[9] < 0x80
);
}
static const uchar bitrates[4][4][16] = {
{
{0},
{0, 4, 8, 12, 16, 20, 24, 28, 32, 40, 48, 56, 64, 72, 80, 0}, /* v2.5 III */
{0, 4, 8, 12, 16, 20, 24, 28, 32, 40, 48, 56, 64, 72, 80, 0}, /* v2.5 II */
{0, 16, 24, 28, 32, 40, 48, 56, 64, 72, 80, 88, 96, 112, 128, 0}, /* v2.5 I */
},
{ {0}, {0}, {0}, {0} },
{
{0},
{0, 4, 8, 12, 16, 20, 24, 28, 32, 40, 48, 56, 64, 72, 80, 0}, /* v2 III */
{0, 4, 8, 12, 16, 20, 24, 28, 32, 40, 48, 56, 64, 72, 80, 0}, /* v2 II */
{0, 16, 24, 28, 32, 40, 48, 56, 64, 72, 80, 88, 96, 112, 128, 0}, /* v2 I */
},
{
{0},
{0, 16, 20, 24, 28, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 0}, /* v1 III */
{0, 16, 24, 28, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 0}, /* v1 II */
{0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, 0}, /* v1 I */
}
};
static const uint samplerates[4][4] = {
{11025, 12000, 8000, 0},
{ 0, 0, 0, 0},
{22050, 24000, 16000, 0},
{44100, 48000, 32000, 0},
};
static const int chans[] = {2, 2, 2, 1};
static const int samplesframe[4][4] = {
{0, 0, 0, 0},
{0, 576, 1152, 384},
{0, 576, 1152, 384},
{0, 1152, 1152, 384},
};
static void
getduration(Tagctx *ctx, int offset)
{
uvlong n, framelen, samplespf, toc;
uchar *b;
uint x;
int xversion, xlayer, xbitrate, i;
if(ctx->read(ctx, ctx->buf, 256) != 256)
return;
x = beuint((uchar*)ctx->buf);
xversion = x >> 19 & 3;
xlayer = x >> 17 & 3;
xbitrate = x >> 12 & 0xf;
ctx->bitrate = 2000*(int)bitrates[xversion][xlayer][xbitrate];
samplespf = samplesframe[xversion][xlayer];
ctx->samplerate = samplerates[xversion][x >> 10 & 3];
ctx->channels = chans[x >> 6 & 3];
if(ctx->samplerate > 0){
framelen = (uvlong)144*ctx->bitrate / ctx->samplerate;
if((x & (1<<9)) != 0) /* padding */
framelen += xlayer == 3 ? 4 : 1; /* for I it's 4 bytes */
if(memcmp(&ctx->buf[0x24], "Info", 4) == 0 || memcmp(&ctx->buf[0x24], "Xing", 4) == 0){
b = (uchar*)ctx->buf + 0x28;
x = beuint(b); b += 4;
if((x & 1) != 0){ /* number of frames is set */
n = beuint(b); b += 4;
ctx->duration = n * samplespf * 1000 / ctx->samplerate;
}
if((x & 2) != 0){ /* file size is set */
n = beuint(b); b += 4;
if(ctx->duration == 0 && framelen > 0)
ctx->duration = n * samplespf * 1000 / framelen / ctx->samplerate;
if((x & 4) != 0 && ctx->toc != nil){ /* TOC is set */
toc = offset + 100 + (char*)b - ctx->buf;
if((x & 8) != 0) /* VBR scale */
toc += 4;
for(i = 0; i < 100; i++){
/*
* offset = n * b[i] / 256
* ms = i * duration / 100
*/
ctx->toc(ctx, i * ctx->duration / 100, toc + (n * b[i]) / 256);
}
b += 100;
if((x & 8) != 0) /* VBR scale */
b += 4;
}
}
offset += (char*)b - ctx->buf;
}else if(memcmp(&ctx->buf[0x24], "VBRI", 4) == 0){
n = beuint((uchar*)&ctx->buf[0x32]);
ctx->duration = n * samplespf * 1000 / ctx->samplerate;
if(ctx->duration == 0 && framelen > 0){
n = beuint((uchar*)&ctx->buf[0x28]); /* file size */
ctx->duration = n * samplespf * 1000 / framelen / ctx->samplerate;
}
}
}
if(ctx->bitrate > 0 && ctx->duration == 0) /* worst case -- use real file size instead */
ctx->duration = (ctx->seek(ctx, 0, 2) - offset)/(ctx->bitrate / 1000) * 8;
}
int
tagid3v2(Tagctx *ctx)
{
int sz, exsz, framesz;
int ver, unsync, offset;
uchar d[10], *b;
if(ctx->read(ctx, d, sizeof(d)) != sizeof(d))
return -1;
if(!isid3(d)){ /* no tags, but the stream information is there */
if(d[0] != 0xff || (d[1] & 0xfe) != 0xfa)
return -1;
ctx->seek(ctx, -(int)sizeof(d), 1);
getduration(ctx, 0);
return 0;
}
header:
ver = d[3];
unsync = d[5] & (1<<7);
sz = synchsafe(&d[6]);
if(ver == 2 && (d[5] & (1<<6)) != 0) /* compression */
return -1;
if(ver > 2){
if((d[5] & (1<<4)) != 0) /* footer */
sz -= 10;
if((d[5] & (1<<6)) != 0){ /* skip extended header */
if(ctx->read(ctx, d, 4) != 4)
return -1;
exsz = (ver >= 3) ? beuint(d) : synchsafe(d);
if(ctx->seek(ctx, exsz, 1) < 0)
return -1;
sz -= exsz;
}
}
framesz = (ver >= 3) ? 10 : 6;
for(; sz > framesz;){
int tsz, frameunsync;
if(ctx->read(ctx, d, framesz) != framesz)
return -1;
sz -= framesz;
/* return on padding */
if(memcmp(d, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", framesz) == 0)
break;
if(ver >= 3){
tsz = (ver == 3) ? beuint(&d[4]) : synchsafe(&d[4]);
if(tsz < 0 || tsz > sz)
break;
frameunsync = d[9] & (1<<1);
d[4] = 0;
if((d[9] & 0x0c) != 0){ /* compression & encryption */
ctx->seek(ctx, tsz, 1);
sz -= tsz;
continue;
}
if(ver == 4 && (d[9] & 1<<0) != 0){ /* skip data length indicator */
ctx->seek(ctx, 4, 1);
sz -= 4;
tsz -= 4;
}
}else{
tsz = beuint(&d[3]) >> 8;
if(tsz > sz)
return -1;
frameunsync = 0;
d[3] = 0;
}
sz -= tsz;
if(d[0] == 'T' && text(ctx, d, tsz, unsync || frameunsync) != 0)
return -1;
else if(d[0] != 'T' && nontext(ctx, d, tsz, unsync || frameunsync) != 0)
return -1;
}
offset = ctx->seek(ctx, sz, 1);
sz = ctx->bufsz <= 2048 ? ctx->bufsz : 2048;
b = nil;
for(exsz = 0; exsz < 2048; exsz += sz){
if(ctx->read(ctx, ctx->buf, sz) != sz)
break;
for(b = (uchar*)ctx->buf; (b = memchr(b, 'I', sz - 1 - ((char*)b - ctx->buf))) != nil; b++){
ctx->seek(ctx, (char*)b - ctx->buf + offset + exsz, 0);
if(ctx->read(ctx, d, sizeof(d)) != sizeof(d))
return 0;
if(isid3(d))
goto header;
}
for(b = (uchar*)ctx->buf; (b = memchr(b, 0xff, sz-3)) != nil; b++){
if((b[1] & 0xe0) == 0xe0){
offset = ctx->seek(ctx, (char*)b - ctx->buf + offset + exsz, 0);
exsz = 2048;
break;
}
}
}
if(b != nil)
getduration(ctx, offset);
return 0;
}