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

2009/6/30 Adam Rosi-Kessel <adam at
rosi-kessel.org>:
> Monty Montgomery wrote, on 6/25/2009 2:16 PM:
>>> Is there any way to understand exactly how it is invalid? I can
replicate
>>> this corruption simply by adding large album art to any ogg file
with the
>>> latest release of MediaMonkey.
>> The second page is corrupt. ?The basic structure looks correct, first
>> guess would be bad checksum. ?I'll look more closely in just a bit.
>> This might explain why some players might accept it--- if they're
>> ignoring checksumming and error detection.
>
> I've noticed that I may have different varieties of corruption. For
> example, this file doesn't have the oversized embedded album art:
>
> 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 :-)

Conrad.

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.

Adam

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