[Tremor] Piece-meal Vorbis decode

[Robert Hui]

Hi,

I'm working with Tremor on a microcontroller board.  I am trying to decode 
an Ogg file from a CF card, but there's not enough internal memory to take 
the entire file in.  So the file is pulled into a temporary packed_buffer, 
and then decoded into a predac_buffer to be sent out to an audio codec.

In this respect, the Ogg file seems like a stream.  How do I decode the 
file if ov_open(..) expects a file pointer (I can't point to a partial file 
with a file pointer, can I?)?  Is there a way to decode Ogg streams where 
the compressed data comes in streaming in a limited fashion?

- Robert Hui