The earlier code relied on the length of clusters always being coded on
eight bytes (as is current Matroska muxer behaviour). But there is no
need to rely on this and this commit changes it.
Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@googlemail.com>
---
libavformat/matroskadec.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
index 7a96e53bdd..f3bc792728 100644
--- a/libavformat/matroskadec.c
+++ b/libavformat/matroskadec.c
@@ -3694,14 +3694,16 @@ static int
webm_clusters_start_with_keyframe(AVFormatContext *s)
before_pos = avio_tell(s->pb);
while (1) {
int64_t cluster_id = 0, cluster_length = 0;
+ int read;
AVPacket *pkt;
avio_seek(s->pb, cluster_pos, SEEK_SET);
// read cluster id and length
- ebml_read_num(matroska, matroska->ctx->pb, 4, &cluster_id);
- ebml_read_length(matroska, matroska->ctx->pb, &cluster_length);
- if (cluster_id != 0xF43B675) { // done with all clusters
+ read = ebml_read_num(matroska, matroska->ctx->pb, 4, &cluster_id);
+ if (read < 0 || cluster_id != 0xF43B675) // done with all clusters
+ break;
+ read = ebml_read_length(matroska, matroska->ctx->pb, &cluster_length);
+ if (read < 0)
break;
- }
avio_seek(s->pb, cluster_pos, SEEK_SET);
matroska->current_id = 0;
matroska_clear_queue(matroska);
@@ -3710,7 +3712,8 @@ static int
webm_clusters_start_with_keyframe(AVFormatContext *s)
break;
}
pkt = &matroska->queue->pkt;
- cluster_pos += cluster_length + 12; // 12 is the offset of the cluster
id and length.
+ // 4 + read is the length of the cluster id and the cluster length
field.
+ cluster_pos += 4 + read + cluster_length;
if (!(pkt->flags & AV_PKT_FLAG_KEY)) {
rv = 0;
break;
--
2.19.2
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