If a file uses unknown-length level 1 elements besides clusters and such
elements are after the first cluster, then these elements will usually
be parsed twice: Once during parsing of the file header and once when
reading the file reaches the position where these elements are located.
The second time the element is parsed leads to a "Duplicate element"
error message. Known-length elements are not affected by this as they
are skipped except during parsing the header.
This commit fixes this by explicitly adding a check for whether the
position of the element to be parsed is the same as the position of the
already known level 1 element.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com>
---
libavformat/matroskadec.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 0bf6477b0e..a4ba9720c6 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -1386,7 +1386,10 @@ static int ebml_parse(MatroskaDemuxContext *matroska,
matroska->cues_parsing_deferred = 0;
if (syntax->type == EBML_LEVEL1 &&
(level1_elem = matroska_find_level1_elem(matroska, syntax->id))) {
- if (level1_elem->parsed)
+ if (!level1_elem->pos) {
+ // Zero is not a valid position for a level 1 element.
+ level1_elem->pos = pos;
+ } else if (level1_elem->pos != pos)
av_log(matroska->ctx, AV_LOG_ERROR, "Duplicate element\n");
level1_elem->parsed = 1;
}
--
2.21.0
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