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Chaining Example CodeThe following is a run-through of the chaining example program supplied with vorbisfile - chaining_example.c. This program demonstrates how to work with a chained bitstream.
First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.
Inside main(), we declare our primary OggVorbis_File structure. We also declare a other helpful variables to track our progress within the file.
ov_open() must be
called to initialize the OggVorbis_File structure with default values.
ov_open() also checks to ensure that we're reading Vorbis format and not something else.
First we check to make sure the stream is seekable using ov_seekable. Then we're going to find the number of logical bitstreams in the physical bitstream using ov_streams. We use ov_time_total to determine the total length of the physical bitstream. We specify that we want the entire bitstream by using the argument -1.
Now we're going to iterate through each logical bitstream and print information about that bitstream. We use ov_info to pull out the vorbis_info struct for each logical bitstream. This struct contains bitstream-specific info. ov_serialnumber retrieves the unique serial number for the logical bistream. ov_raw_total gives the total compressed bytes for the logical bitstream, and ov_time_total gives the total time in the logical bitstream.
When we're done with the entire physical bitstream, we need to call ov_clear() to release the bitstream.
The full source for chaining_example.c can be found with the vorbis
distribution in chaining_example.c.
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