On Mon, 27 May 2013 13:13:25 -0400, Sean McGovern <[email protected]> wrote:
> This allows handling matroska files with errors.
> Fixes test4.mkv and test7.mkv from the official Matroska test suite,
> and by extension Bugzilla #62.
>
> Based on a patch by Reimar Doffinger <[email protected]>
> ---
> Once again, with feeling!
> ---
> libavformat/matroskadec.c | 50
> ++++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 45 insertions(+), 5 deletions(-)
>
> diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c
> index 744f7c0..76d05b3 100644
> --- a/libavformat/matroskadec.c
> +++ b/libavformat/matroskadec.c
> @@ -556,6 +556,36 @@ static EbmlSyntax matroska_clusters_incremental[] = {
>
> static const char *const 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)
I kinda fail to see what is the part after || for.
If avio_seek succeeds, but does not put us where we asked, then something is
really wrong elsewhere.
> + goto eof;
> +
> + id = avio_rb32(pb);
> +
> + // try to find a toplevel element
> + while (!pb->eof_reached) {
> + 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)
> + {
This could use some vertical alignment and the { should be on the previous line
> + 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.
> */
> @@ -1361,6 +1391,7 @@ 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, res;
> @@ -1391,8 +1422,16 @@ 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)
> @@ -2013,7 +2052,7 @@ 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 n;
> + return AVERROR_INVALIDDATA;
Does not look related.
> }
> data += n;
> size -= n;
> @@ -2187,7 +2226,6 @@ static int matroska_parse_cluster(MatroskaDemuxContext
> *matroska)
> pos);
> }
> ebml_free(matroska_cluster, &cluster);
> - if (res < 0) matroska->done = 1;
> return res;
> }
>
> @@ -2197,9 +2235,11 @@ static int matroska_read_packet(AVFormatContext *s,
> AVPacket *pkt)
> int ret = 0;
>
> while (!ret && matroska_deliver_packet(matroska, pkt)) {
> + int64_t pos = avio_tell(matroska->ctx->pb);
> if (matroska->done)
> return AVERROR_EOF;
> - ret = matroska_parse_cluster(matroska);
> + if (matroska_parse_cluster(matroska) < 0)
> + ret = matroska_resync(matroska, pos);
> }
Otherwise looks mostly ok.
--
Anton Khirnov
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