[FFmpeg-trac] #8001(avformat:new): FFmpeg fails to read MKV after 2GiB

FFmpeg trac at avcodec.org
Sat Jul 6 19:30:09 EEST 2019

#8001: FFmpeg fails to read MKV after 2GiB
             Reporter:  Anton1699     |                    Owner:
                 Type:  defect        |                   Status:  new
             Priority:  important     |                Component:  avformat
              Version:  git-master    |               Resolution:
             Keywords:  matroska mkv  |               Blocked By:
             Blocking:                |  Reproduced by developer:  1
Analyzed by developer:  1             |
Changes (by mkver):

 * analyzed:  0 => 1
 * component:  undetermined => avformat
 * reproduced:  0 => 1


 Regression since a569a7b3bb017315b954ca686e1e8add05f07f09
 An overflow happened in "res = avio_skip(pb, length);" if the new position
 was >= 2 GB and < 4 GB etc. because res is an just an int. This happens
 when there are elements to be skipped, like the CRC-32 elements that our
 Matroska muxer adds by default; files created by mkvmerge don't have such
 elements, which explains the result of your further investigation.
 This line has been changed in ff5ea59f7b05cb4d37ba9e2c3ee383ff24a10ae0,
 but the overflow is still there.
 Sorry for this.

Ticket URL: <https://trac.ffmpeg.org/ticket/8001#comment:2>
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