This partially opens a vorbis file to test for Vorbis-ness. It loads
the headers for the first chain, and tests for seekability (but does not seek).
Use ov_test_open() to finish opening the file
or ov_clear to close/free it.
int ov_test(FILE *f,OggVorbis_File *vf,char *initial,long ibytes);
Parameters
f
File pointer to an already opened file
or pipe (it need not be seekable--though this obviously restricts what
can be done with the bitstream).
vf
A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
functions. Once this has been called, the same OggVorbis_File
struct should be passed to all the libvorbisfile functions.
initial
Typically set to NULL. This parameter is useful if some data has already been
read from the file and the stream is not seekable. It is used in conjunction with ibytes. In this case, initial
should be a pointer to a buffer containing the data read.
ibytes
Typically set to 0. This parameter is useful if some data has already been
read from the file and the stream is not seekable. In this case, ibytes
should contain the length (in bytes) of the buffer. Used together with initial
Return Values
0 for success
less than zero for failure:
OV_EREAD - A read from media returned an error.
OV_ENOTVORBIS - Bitstream is not Vorbis data.
OV_EVERSION - Vorbis version mismatch.
OV_EBADHEADER - Invalid Vorbis bitstream header.
OV_EFAULT - Internal logic fault; indicates a bug or heap/stack corruption.