From a4fb905a14c1ab6d14bf38412e7fccbfed09a556 Mon Sep 17 00:00:00 2001 From: Chris Cunningham Date: Fri, 3 Feb 2017 14:42:44 -0800 Subject: [PATCH] lavf/matroskadec: fix is_keyframe for early Blocks Blocks are marked as key frames whenever the "reference" field is zero. This breaks for non-keyframe Blocks with a reference timestamp of zero. The likelihood of reference timestamp being zero is increased by a longstanding bug in muxing that encodes reference timestamp as the absolute time of the referenced frame (rather than relative to the current Block timestamp, as described in MKV spec). Now using INT64_MIN to denote "no reference". Reported to chromium at http://crbug.com/497889 (contains sample) (cherry picked from commit ac25840ee32888f0c13118edeb9404a123cd3a79) Signed-off-by: Michael Niedermayer --- libavformat/matroskadec.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index 3c7ab1c9c5..1d83068f88 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -88,6 +88,7 @@ typedef const struct EbmlSyntax { int list_elem_size; int data_offset; union { + int64_t i; uint64_t u; double f; const char *s; @@ -675,7 +676,7 @@ static const EbmlSyntax matroska_blockgroup[] = { { MATROSKA_ID_SIMPLEBLOCK, EBML_BIN, 0, offsetof(MatroskaBlock, bin) }, { MATROSKA_ID_BLOCKDURATION, EBML_UINT, 0, offsetof(MatroskaBlock, duration) }, { MATROSKA_ID_DISCARDPADDING, EBML_SINT, 0, offsetof(MatroskaBlock, discard_padding) }, - { MATROSKA_ID_BLOCKREFERENCE, EBML_SINT, 0, offsetof(MatroskaBlock, reference) }, + { MATROSKA_ID_BLOCKREFERENCE, EBML_SINT, 0, offsetof(MatroskaBlock, reference), { .i = INT64_MIN } }, { MATROSKA_ID_CODECSTATE, EBML_NONE }, { 1, EBML_UINT, 0, offsetof(MatroskaBlock, non_simple), { .u = 1 } }, { 0 } @@ -1048,6 +1049,9 @@ static int ebml_parse_nest(MatroskaDemuxContext *matroska, EbmlSyntax *syntax, for (i = 0; syntax[i].id; i++) switch (syntax[i].type) { + case EBML_SINT: + *(int64_t *) ((char *) data + syntax[i].data_offset) = syntax[i].def.i; + break; case EBML_UINT: *(uint64_t *) ((char *) data + syntax[i].data_offset) = syntax[i].def.u; break; @@ -3267,7 +3271,7 @@ static int matroska_parse_cluster_incremental(MatroskaDemuxContext *matroska) matroska->current_cluster_num_blocks = blocks_list->nb_elem; i = blocks_list->nb_elem - 1; if (blocks[i].bin.size > 0 && blocks[i].bin.data) { - int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1; + int is_keyframe = blocks[i].non_simple ? blocks[i].reference == INT64_MIN : -1; uint8_t* additional = blocks[i].additional.size > 0 ? blocks[i].additional.data : NULL; if (!blocks[i].non_simple) @@ -3305,7 +3309,7 @@ static int matroska_parse_cluster(MatroskaDemuxContext *matroska) blocks = blocks_list->elem; for (i = 0; i < blocks_list->nb_elem; i++) if (blocks[i].bin.size > 0 && blocks[i].bin.data) { - int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1; + int is_keyframe = blocks[i].non_simple ? blocks[i].reference == INT64_MIN : -1; res = matroska_parse_block(matroska, blocks[i].bin.data, blocks[i].bin.size, blocks[i].bin.pos, cluster.timecode, blocks[i].duration,