[ogg-dev] Fixing ogg vorbis corruption caused by bad metadata

Monty Montgomery monty at xiph.org
Mon Jul 13 22:44:34 PDT 2009


On Tue, Jul 14, 2009 at 1:41 AM, Erik de Castro
Lopo<mle+la at mega-nerd.com> wrote:
> Monty Montgomery wrote:
>
>> Yes.  Without the first three packets (which hold all the codec
>> settings and all the instruction how to handle the subsequent packets)
>> the rest of the stream is gibberish.  Vorbis can't even unpack the
>> bits without the codebooks packed into the third header.
>
> Curiosity man here.
>
> Is there a finite set of predetermined codebooks or is the codebook
> source dependent?

Both-- The current encoders use predetermined books, but its a large
set.  And the set has often changed between releases.

The set is small enough that its possible to make good reasonable guesses.

Monty


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