[FFmpeg-devel] [PATCH] matroskadec: verify seekhead IDs

Michael Niedermayer michaelni at gmx.at
Fri Jun 12 19:30:47 CEST 2015

On Fri, Jun 12, 2015 at 01:11:41PM +0200, wm4 wrote:
> Some files have SeekHead elements with broken IDs. They mismatch with
> the ID of the destination element. These files are written by
> "IDMmkvlib0.1" (as identified by the MuxingApp and WritingApp elements),
> and the SeekHead IDs are actually endian-swapped.
> This confuses the SeekHead logic of the demuxer. It will read some
> elements twice, because the SeekHead ID is used to identify and remember
> already read elements. With the file at hand, the stream list was
> duplicated by reading the Tracks element twice.
> Fix this by rejecting invalid EBML IDs in SeekHead entries. (This fix is
> relatively specific to the broken file at hand, and doesn't protect
> against some other cases of broken SeekHead, such as valid but
> mismatching target element IDs.)
> ---
>  libavformat/matroskadec.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)



Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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