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matroskadec: introduce resync function. 

This allows handling matroska files with errors.
Fixes test4.mkv and test7.mkv from the official Matroska test suite.
These are also trac issues #544 and #545.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
This commit is contained in:
Reimar Döffinger 2012-02-13 23:06:19 +01:00
parent 9e0f897fe5
commit d493170ec9
1 changed files with 46 additions and 6 deletions
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52
libavformat/matroskadec.c
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@ -544,6 +544,36 @@ static EbmlSyntax matroska_clusters[] = {
static const char *matroska_doctypes[] = { "matroska", "webm" };
static int matroska_resync(MatroskaDemuxContext *matroska, int64_t last_pos)
{
AVIOContext *pb = matroska->ctx->pb;
uint32_t id;
matroska->current_id = 0;
matroska->num_levels = 0;
// seek to next position to resync from
if (avio_seek(pb, last_pos + 1, SEEK_SET) < 0 || avio_tell(pb) <= last_pos)
goto eof;
id = avio_rb32(pb);
// try to find a toplevel element
while (!url_feof(pb)) {
if (id == MATROSKA_ID_INFO || id == MATROSKA_ID_TRACKS ||
id == MATROSKA_ID_CUES || id == MATROSKA_ID_TAGS ||
id == MATROSKA_ID_SEEKHEAD || id == MATROSKA_ID_ATTACHMENTS ||
id == MATROSKA_ID_CLUSTER || id == MATROSKA_ID_CHAPTERS)
{
matroska->current_id = id;
return 0;
}
id = (id << 8) | avio_r8(pb);
}
eof:
matroska->done = 1;
return AVERROR_EOF;
}
/*
* Return: Whether we reached the end of a level in the hierarchy or not.
*/
@ -1322,6 +1352,7 @@ static int matroska_read_header(AVFormatContext *s)
MatroskaChapter *chapters;
MatroskaTrack *tracks;
uint64_t max_start = 0;
int64_t pos;
Ebml ebml = { 0 };
AVStream *st;
int i, j, k, res;
@ -1353,8 +1384,16 @@ static int matroska_read_header(AVFormatContext *s)
ebml_free(ebml_syntax, &ebml);
/* The next thing is a segment. */
if ((res = ebml_parse(matroska, matroska_segments, matroska)) < 0)
return res;
pos = avio_tell(matroska->ctx->pb);
res = ebml_parse(matroska, matroska_segments, matroska);
// try resyncing until we find a EBML_STOP type element.
while (res != 1) {
res = matroska_resync(matroska, pos);
if (res < 0)
return res;
pos = avio_tell(matroska->ctx->pb);
res = ebml_parse(matroska, matroska_segment, matroska);
}
matroska_execute_seekhead(matroska);
if (!matroska->time_scale)
@ -1744,7 +1783,7 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
if ((n = matroska_ebmlnum_uint(matroska, data, size, &num)) < 0) {
av_log(matroska->ctx, AV_LOG_ERROR, "EBML block data error\n");
return res;
return AVERROR_INVALIDDATA;
}
data += n;
size -= n;
@ -1753,7 +1792,7 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, uint8_t *data,
if (!track || !track->stream) {
av_log(matroska->ctx, AV_LOG_INFO,
"Invalid stream %"PRIu64" or size %u\n", num, size);
return res;
return AVERROR_INVALIDDATA;
} else if (size <= 3)
return 0;
st = track->stream;
@ -2001,7 +2040,6 @@ static int matroska_parse_cluster(MatroskaDemuxContext *matroska)
pos);
}
ebml_free(matroska_cluster, &cluster);
if (res < 0) matroska->done = 1;
return res;
}
@ -2010,9 +2048,11 @@ static int matroska_read_packet(AVFormatContext *s, AVPacket *pkt)
MatroskaDemuxContext *matroska = s->priv_data;
while (matroska_deliver_packet(matroska, pkt)) {
int64_t pos = avio_tell(matroska->ctx->pb);
if (matroska->done)
return AVERROR_EOF;
matroska_parse_cluster(matroska);
if (matroska_parse_cluster(matroska) < 0)
matroska_resync(matroska, pos);
}
return 0;