theora_decode_header

Hello,

I am using theora in an application, but it does not work, I was looking 
to know why, and since I have one application using theora, I checked 
the difference between the two executions.
And it seems that the function *_theora_decode_header_* does not have 
the same issue in the two application, but I read the same file...
the difference is on the _m_theoraInfo_, in the first application ( 
which work ) the offset_y is equal to 4, and in the second application 
(which does not work) the offset_y is equal to 0.
that's the same file at two differente place in the file system, but I 
suppose that changes nothing ?
How can I get differente information about the same file ??

Vincent.