[FFmpeg-user] oggdec and corrupted OGG Vorbis file

Moritz Barsnick barsnick at gmx.net
Thu Jul 14 00:31:40 EEST 2016

On Wed, Jul 13, 2016 at 18:08:30 +0100, Samuel Silimangala wrote:

Why don't you reply to the proper message on the mailing list? You
broke the thread, and people can't follow the conversation.

> As everybody can saw
> https://trac.ffmpeg.org/attachment/ticket/5706/OGG%20Vorbis.txt
> Duration : 5 min
> https://we.tl/B66DqK7tmC
> That was the pieces sended for the ticket.
> So, i don't understand why you persist to tell that my input and
> output are same, 7:02 mins, when they are not ?

They are. If you play the file in any tool, it will certainly play for
7:02 minutes.

What's wrong is that the corrupt file you provided *claims* to be 5
minutes long. That's because that is the information provided in the
header(s) (depending on file format, in the container and stream
headers - in this case both). ffmpeg and most other tools initially
rely on the information the header, as to not decode the complete file
just in order to know its "real" length.

So whatever tool created this file provided incorrect information in
the header. Luckily for you, ffmpeg kindly decodes the complete
content, ignoring the broken header.

If you do not trust the headers of a file or its streams (Ogg or any
other format), you most often need to decode them in their entirety to
determine their length.


P.S.: Why do you insist here, when the whole thing was clarified in the
      trac ticket 28 hours ago? Why do I even bother?

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