The ID3v2 "unsynchronization scheme" requires replacing any 0xFF 0x00
sequences with 0xFF. This has to be done on every byte of the source
data, while the current code skipped a byte after a replacement. This
meant 0xFF 0x00 0xFF 00 was translated to 0xFF 0xFF 0x00 instead of 0xFF
0xFF. It feels a bit messy to do this correctly with the avio use. But
fortunately, this translation can be done in-place, so we can just do it
in memory.
Inspired by what taglib does.
Also see
9ae80e6a9cefcab61e867256ba19ef78a4bfe0cb. (The sample file for
that commit is gone, so it could not be retested.)
}
}
if (unsync || tunsync) {
- int64_t end = avio_tell(pb) + tlen;
- uint8_t *b;
-
- b = buffer;
- while (avio_tell(pb) < end && b - buffer < tlen && !pb->eof_reached) {
- *b++ = avio_r8(pb);
- if (*(b - 1) == 0xff && avio_tell(pb) < end - 1 &&
- b - buffer < tlen &&
- !pb->eof_reached ) {
- uint8_t val = avio_r8(pb);
- *b++ = val ? val : avio_r8(pb);
- }
+ uint8_t *b = buffer;
+ uint8_t *t = buffer;
+ uint8_t *end = t + tlen;
+
+ if (avio_read(pb, buffer, tlen) != tlen) {
+ av_log(s, AV_LOG_ERROR, "Failed to read tag data\n");
+ goto seek;
}
+
+ while (t != end) {
+ *b++ = *t++;
+ if (t != end && t[-1] == 0xff && !t[0])
+ t++;
+ }
+
ffio_init_context(&pb_local, buffer, b - buffer, 0, NULL, NULL, NULL,
NULL);
tlen = b - buffer;