From 1b4d327b1c7ab01495ea896cf9034d5eed8c4893 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Reimar=20D=C3=B6ffinger?= Date: Mon, 6 Sep 2010 17:51:44 +0000 Subject: [PATCH] Add a special function to mkv demxuer to parse length values that includes special-case code to handle all possible encodings of "unknown length". Originally committed as revision 25049 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavformat/matroskadec.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index 888f099ff..0d0285e6c 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -575,6 +575,20 @@ static int ebml_read_num(MatroskaDemuxContext *matroska, ByteIOContext *pb, return read; } +/** + * Read a EBML length value. + * This needs special handling for the "unknown length" case which has multiple + * encodings. + */ +static int ebml_read_length(MatroskaDemuxContext *matroska, ByteIOContext *pb, + uint64_t *number) +{ + int res = ebml_read_num(matroska, pb, 8, number); + if (res > 0 && *number + 1 == 1ULL << (7 * res)) + *number = 0xffffffffffffffULL; + return res; +} + /* * Read the next element as an unsigned int. * 0 is success, < 0 is failure. @@ -782,7 +796,7 @@ static int ebml_parse_elem(MatroskaDemuxContext *matroska, if (syntax->type != EBML_PASS && syntax->type != EBML_STOP) { matroska->current_id = 0; - if ((res = ebml_read_num(matroska, pb, 8, &length)) < 0) + if ((res = ebml_read_length(matroska, pb, &length)) < 0) return res; } -- 2.11.0