mirror of https://git.ffmpeg.org/ffmpeg.git
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)
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@ -89,6 +89,7 @@ typedef const struct EbmlSyntax {
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int list_elem_size;
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int data_offset;
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union {
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int64_t i;
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uint64_t u;
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double f;
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const char *s;
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@ -696,7 +697,7 @@ static const EbmlSyntax matroska_blockgroup[] = {
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{ MATROSKA_ID_SIMPLEBLOCK, EBML_BIN, 0, offsetof(MatroskaBlock, bin) },
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{ MATROSKA_ID_BLOCKDURATION, EBML_UINT, 0, offsetof(MatroskaBlock, duration) },
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{ MATROSKA_ID_DISCARDPADDING, EBML_SINT, 0, offsetof(MatroskaBlock, discard_padding) },
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{ MATROSKA_ID_BLOCKREFERENCE, EBML_SINT, 0, offsetof(MatroskaBlock, reference) },
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{ MATROSKA_ID_BLOCKREFERENCE, EBML_SINT, 0, offsetof(MatroskaBlock, reference), { .i = INT64_MIN } },
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{ MATROSKA_ID_CODECSTATE, EBML_NONE },
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{ 1, EBML_UINT, 0, offsetof(MatroskaBlock, non_simple), { .u = 1 } },
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{ 0 }
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@ -1071,6 +1072,9 @@ static int ebml_parse_nest(MatroskaDemuxContext *matroska, EbmlSyntax *syntax,
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for (i = 0; syntax[i].id; i++)
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switch (syntax[i].type) {
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case EBML_SINT:
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*(int64_t *) ((char *) data + syntax[i].data_offset) = syntax[i].def.i;
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break;
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case EBML_UINT:
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*(uint64_t *) ((char *) data + syntax[i].data_offset) = syntax[i].def.u;
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break;
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@ -3361,7 +3365,7 @@ static int matroska_parse_cluster_incremental(MatroskaDemuxContext *matroska)
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matroska->current_cluster_num_blocks = blocks_list->nb_elem;
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i = blocks_list->nb_elem - 1;
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if (blocks[i].bin.size > 0 && blocks[i].bin.data) {
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int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1;
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int is_keyframe = blocks[i].non_simple ? blocks[i].reference == INT64_MIN : -1;
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uint8_t* additional = blocks[i].additional.size > 0 ?
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blocks[i].additional.data : NULL;
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if (!blocks[i].non_simple)
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@ -3399,7 +3403,7 @@ static int matroska_parse_cluster(MatroskaDemuxContext *matroska)
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blocks = blocks_list->elem;
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for (i = 0; i < blocks_list->nb_elem; i++)
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if (blocks[i].bin.size > 0 && blocks[i].bin.data) {
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int is_keyframe = blocks[i].non_simple ? !blocks[i].reference : -1;
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int is_keyframe = blocks[i].non_simple ? blocks[i].reference == INT64_MIN : -1;
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res = matroska_parse_block(matroska, blocks[i].bin.data,
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blocks[i].bin.size, blocks[i].bin.pos,
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cluster.timecode, blocks[i].duration,
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