oggparsetheora: fix metadata parsing

Fixes Ticket1508
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/oggparsetheora.c

@@ -110,7 +110,7 @@ theora_header (AVFormatContext * s, int idx)
         st->codec->codec_id = AV_CODEC_ID_THEORA;
         st->need_parsing = AVSTREAM_PARSE_HEADERS;
 
-    } else if (os->buf[os->pstart] == 0x83) {
+    } else if (os->buf[os->pstart] == 0x81) {
         ff_vorbis_comment (s, &st->metadata, os->buf + os->pstart + 7, os->psize - 8);
     }