[FFmpeg-devel] Serious Regression in matroskaenc:

Paul B Mahol onemda at gmail.com
Fri Dec 23 13:21:19 EET 2016

On 12/23/16, Soft Works <softworkz at hotmail.com> wrote:
> Hello everybody,
> it's been a while since my contribution to matroskaenc in July. In case you
> don't remember my scenario - it's about realtime transcoding and and
> streaming of mkv files.
> That means that the header is sent to the client before the ffmpeg process
> is completed.
> In this context we discovered that the preliminary mkv header that is
> written initially is corrupted in some way!
> When transcoding is aborted or completed, the header is written a second
> time, overwriting a few things. This final header write operation always
> fixes the problem and leaves the file with a correct header.
> I haven't investigated yet, what's actually being written wrong. I used
> different parsing implementations (mediainfo, ffprobe, mkvvalidator,
> mkvtoolnix) and all are producing different results. Some report CRC error,
> others report unknown or duplicate header elements. Some are able to detect
> the stream information others are not.
> Now, I'm wondering if one of you guys could take care of this? Or do I have
> to find the bug on my own?

Do you have steps to reproduce this?

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