ogg dev - Jul 2009 - Fixing ogg vorbis corruption caused by bad metadata

Adam Rosi-Kessel wrote, on 6/30/2009 11:14 AM:
> Conrad Parker wrote, on 6/30/2009 11:05 AM:
>>> http://adam.rosi-kessel.org/bugs/liboggz/484/other_corruption.ogg
>>> Yet also won't play or process properly with oggz or hogg
tools. Any
>>> ideas whether this is the same or different root cause? (In all of
these
>>> cases, I'm reasonably certain that disk corruption is not an
issue).
>> that one is entirely missing the comments data, and the second page is
>> incorrectly marked as continued. Not sure that helps with
>> understanding the problem, but I can confirm that it's broken in a
>> different way :-)
>
> Thanks. Is there some reason, in principle, that there couldn't be a
> tool that just extracted the valid packets and created a new valid file
> from there, discarding everything that is invalid? In other words, a
> generic tool that would do its best to make an invalid file playable again.
>
> If there's no reason in principle, would such a tool be easy to create
> by tweaking the existing code base? I've tried to do a little hacking
> myself to figure this out, but it seems like it's a fairly low level
fix
> that's needed. All of the higher level tools (e.g. modules for Perl,
> Python, or Haskell) treat these files identically.
>
> I don't think I've done anything crazy with my files to get them in
> these states -- just used reasonably popular tagging tools that
> apparently have gone astray.
Hi All:

Anything I can do to keep this on radar? I'm not sure if it is really a 
bug -- perhaps at least a wishlist request. Will putting it in a tracker 
somewhere help?

Adam

2009/7/9 Adam Rosi-Kessel <adam at
rosi-kessel.org>:
> Adam Rosi-Kessel wrote, on 6/30/2009 11:14 AM:
>>
>> Conrad Parker wrote, on 6/30/2009 11:05 AM:
>>>>
>>>>
http://adam.rosi-kessel.org/bugs/liboggz/484/other_corruption.ogg
>>>> Yet also won't play or process properly with oggz or hogg
tools. Any
>>>> ideas whether this is the same or different root cause? (In all
of these
>>>> cases, I'm reasonably certain that disk corruption is not
an issue).
>>>
>>> that one is entirely missing the comments data, and the second page
is
>>> incorrectly marked as continued. Not sure that helps with
>>> understanding the problem, but I can confirm that it's broken
in a
>>> different way :-)
>>
>> Thanks. Is there some reason, in principle, that there couldn't be
a
>> tool that just extracted the valid packets and created a new valid file
>> from there, discarding everything that is invalid? In other words, a
>> generic tool that would do its best to make an invalid file playable
>> again.
>>
>> If there's no reason in principle, would such a tool be easy to
create
>> by tweaking the existing code base? I've tried to do a little
hacking
>> myself to figure this out, but it seems like it's a fairly low
level fix
>> that's needed. All of the higher level tools (e.g. modules for
Perl,
>> Python, or Haskell) treat these files identically.
>>
>> I don't think I've done anything crazy with my files to get
them in
>> these states -- just used reasonably popular tagging tools that
>> apparently have gone astray.
>
> Hi All:
>
> Anything I can do to keep this on radar? I'm not sure if it is really a
bug
> -- perhaps at least a wishlist request. Will putting it in a tracker
> somewhere help?
yes, a tracker would help.

At this point it really looks like some pretty bizarre and
inconsistent corruption, which would probably need some custom tools
to fix.

Conrad.

Conrad Parker wrote, on 7/8/2009 8:20 PM:
>> Anything I can do to keep this on radar? I'm not sure if it is
really a bug
>> -- perhaps at least a wishlist request. Will putting it in a tracker
>> somewhere help?
> yes, a tracker would help.
I'm somewhat confused about the right place to file this--can you 
suggest? There seem to be few separate projects it might belong to.
> At this point it really looks like some pretty bizarre and
> inconsistent corruption, which would probably need some custom tools
> to fix.
Is it impractical to suggest a generic tool that simply starts reading 
an ogg file from the beginning, and once it gets past any corruption it 
outputs the rest as a valid file? For example, if you just split an ogg 
vorbis file in half, and only had the second half, is there no currently 
existing tool, or one that could be easily developed from the existing 
libraries, that would take that second half and make it playable?

I do think these problems are actually not that unusual based on the 
number of unanswered threads from other people I've found around other 
discussion lists on trying to repair broken files. And the corruption is 
completely reproducible with MediaMonkey, a very common metadata tagging 
tool. I understand this is probably MediaMonkey's problem/fault 
(although they seem to use the generic ogg/vorbis libraries for 
metadata), but it does leave the fact that there may be many people with 
this problem or a variant thereof out there.

Adam