ref: 4a7f42e378e27bf70c928b411ac859c870c23f24
dir: /vorbis.c/
/*
* https://xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-810005
* https://wiki.xiph.org/VorbisComment
*/
#include "tagspriv.h"
static const struct {
char *s;
int type;
}t[] = {
{"album artist", Talbumartist}, // some legacy leftovers
{"album", Talbum},
{"albumartist", Talbumartist},
{"artist", Tartist},
{"comment", Tcomment},
{"composer", Tcomposer},
{"date", Tdate},
{"genre", Tgenre},
{"r128_album_gain", Talbumgain},
{"r128_track_gain", Ttrackgain},
{"replaygain_album_gain", Talbumgain},
{"replaygain_album_peak", Talbumpeak},
{"replaygain_track_gain", Ttrackgain},
{"replaygain_track_peak", Ttrackpeak},
{"title", Ttitle},
{"tracknumber", Ttrack},
};
void
cbvorbiscomment(Tagctx *ctx, char *k, char *v)
{
int i;
if(*v == 0)
return;
for(i = 0; i < nelem(t); i++){
if(strcasecmp(k, t[i].s) == 0){
txtcb(ctx, t[i].type, k, v);
break;
}
}
if(i == nelem(t))
txtcb(ctx, Tunknown, k, v);
}
static int
mbpdec(void *buf, int *cnt)
{
int sz, n;
uint8_t *v;
v = buf;
if((n = debase64(v, *cnt, v, *cnt)) <= 0)
return -1;
/* skip id3v2 APIC type */
v += 4; n -= 4;
sz = beuint(v); /* mime size */
v += 4; n -= 4;
if(sz < 0 || sz >= n-4-4-4-4-4-4)
return -1;
v += sz; n -= sz; /* skip MIME */
sz = beuint(v); /* description size */
v += 4; n -= 4;
if(sz < 0 || sz >= n-4-4-4-4-4)
return -1;
v += sz; n -= sz; /* skip description */
v += 4+4+4+4; n -= 4+4+4+4; /* skip width, height, depth, palette info */
sz = beuint(v); /* picture size */
v += 4; n -= 4;
if(sz <= 0 || sz > n)
return -1;
memmove(buf, v, sz);
*cnt = sz;
return 0;
}
int
cbmbp(Tagctx *ctx, char *v, int ssz, int off, int picsz)
{
char *mime;
int type, n, sz;
n = ssz; /* at most this amount is available */
n &= ~3; /* modulo 4 sextets, so debase64 gets complete bytes */
n = debase64((uint8_t*)v, n, (uint8_t*)ctx->buf, ctx->bufsz);
/* https://xiph.org/flac/format.html#metadata_block_picture */
if(n <= 4+4+0+4+0+4+4+4+4+4+0)
return 0;
v = ctx->buf;
type = beuint(v); /* id3v2 APIC type */
v += 4; n -= 4;
sz = beuint(v); /* mime size */
v += 4; n -= 4;
if(sz < 0 || sz >= n-4-4-4-4-4-4)
return -1;
mime = v;
v += sz; n -= sz; /* skip MIME */
sz = beuint(v); /* description size */
v += 4; n -= 4;
if(sz < 0 || sz >= n-4-4-4-4-4)
return -1;
*v = 0; /* null-terminate MIME */
tagscallcb(ctx, Timage, &(Tag){.image = {
.mime = mime,
.offset = off,
.size = picsz,
.type = type,
.decode = mbpdec,
}});
return 0;
}
int
tagvorbis(Tagctx *ctx)
{
char *v;
uint8_t *d, h[4];
int sz, numtags, i, npages, pgend, skip;
d = (uint8_t*)ctx->buf;
/* need to find vorbis frame with type=3 */
for(npages = pgend = 0; npages < 2; npages++){ /* vorbis comment is the second header */
int nsegs;
if(ctx->read(ctx, d, 27) != 27)
return -1;
if(memcmp(d, "OggS", 4) != 0)
return -1;
/* calculate the size of the packet */
nsegs = d[26];
if(ctx->read(ctx, d, nsegs+1) != nsegs+1)
return -1;
for(sz = i = 0; i < nsegs; sz += d[i++]);
if(d[nsegs] == 3){ /* comment */
/* FIXME - embedded pics make tags span multiple packets */
pgend = ctx->seek(ctx, 0, 1) + sz;
break;
}
if(d[nsegs] == 1 && sz >= 28){ /* identification */
if(ctx->read(ctx, d, 28) != 28)
return -1;
sz -= 28;
ctx->channels = d[10];
ctx->samplerate = leuint(&d[11]);
if((ctx->bitrate = leuint(&d[15])) == 0) /* maximum */
ctx->bitrate = leuint(&d[19]); /* nominal */
}
ctx->seek(ctx, sz-1, 1);
}
if(npages < 3) {
if(ctx->read(ctx, &d[1], 10) != 10 || memcmp(&d[1], "vorbis", 6) != 0)
return -1;
sz = leuint(&d[7]);
if(ctx->seek(ctx, sz, 1) < 0 || ctx->read(ctx, h, 4) != 4)
return -1;
numtags = leuint(h);
for(i = 0; i < numtags; i++){
if(ctx->read(ctx, h, 4) != 4)
return -1;
if((sz = leuint(h)) < 0)
return -1;
/* FIXME - embedded pics make tags span multiple packets */
if(pgend < ctx->seek(ctx, 0, 1)+sz)
break;
skip = 0;
if(sz > ctx->bufsz-1){
skip = sz - (ctx->bufsz-1);
sz -= skip;
}
if(ctx->read(ctx, ctx->buf, sz) != sz)
return -1;
ctx->buf[sz] = 0;
if((v = strchr(ctx->buf, '=')) == nil)
return -1;
*v++ = 0;
if(strcasecmp(ctx->buf, "metadata_block_picture") != 0)
cbvorbiscomment(ctx, ctx->buf, v);
else if(cbmbp(ctx, v,
sz - (v - ctx->buf), /* at most this amount is available */
ctx->seek(ctx, 0, 1) - sz + (v - ctx->buf), /* offset */
sz + skip - (v - ctx->buf) /* total pic size (still encoded) */
) != 0)
return -1;
if(ctx->seek(ctx, skip, 1) < 0)
return -1;
}
}
/* calculate the duration */
if(ctx->samplerate > 0){
sz = ctx->bufsz <= 4096 ? ctx->bufsz : 4096;
for(i = sz; i < 65536+16; i += sz - 16){
if(ctx->seek(ctx, -i, 2) <= 0)
break;
v = ctx->buf;
if(ctx->read(ctx, v, sz) != sz)
break;
for(; v != nil && v < ctx->buf+sz;){
v = memchr(v, 'O', ctx->buf+sz - v - 14);
if(v != nil && v[1] == 'g' && v[2] == 'g' && v[3] == 'S' && (v[5] & 4) == 4){ /* last page */
uint64_t g = leuint(v+6) | (uint64_t)leuint(v+10)<<32;
ctx->duration = g * 1000 / ctx->samplerate;
}
if(v != nil)
v++;
}
if(ctx->duration != 0)
break;
}
}
return 0;
}