Setup/Teardown

In order to decode audio using libvorbisfile, a bitstream containing vorbis audio must be properly initialized and cleared when decoding is finished.

All the vorbisfile initialization and deallocation routines are declared in "vorbis/vorbisfile.h".

function	purpose
ov_open	Initializes the Ogg Vorbis bitstream with a pointer to a bitstream and default values. This must be called before other functions in the library may be used.
ov_open_callbacks	Initializes the Ogg Vorbis bitstream with a pointer to a bitstream, default values, and custom file/bitstream manipulation routines. Used instead of ov_open when working with a data source other than a file.
ov_clear	Closes the bitstream and cleans up loose ends. Must be called when we're done with the bitstream.
ov_test	Partially opens a vorbis file for testing.
ov_test_callbacks	Same as above but useful for non-files like streams.
ov_test_open		Finish open a file opened for testing.