xiph
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vorbis
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<title>vorbisfile - Example Code</title>
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<td><p class=tiny>vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.25 - 20000615</p></td>
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<h1>Chaining Example Code</h1>

<p>
The following is a run-through of the chaining example program supplied
with vorbisfile - <a href="chaining_example_c.html">chaining_example.c</a>.  
This program demonstrates how to work with a chained bitstream.

<p>
First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.

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#include "vorbis/codec.h"
#include "vorbis/vorbisfile.h"
#include "../lib/misc.h"
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<p>Inside main(), we declare our primary OggVorbis_File structure.  We also declare a other helpful variables to track our progress within the file.
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int main(){
  OggVorbis_File ov;
  int i;
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<p><a href="ov_open.html">ov_open()</a> must be
called to initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> structure with default values.  
<a href="ov_open.html">ov_open()</a> also checks to ensure that we're reading Vorbis format and not something else.

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  if(ov_open(stdin,&ov,NULL,-1)<0){
    printf("Could not open input as an OggVorbis file.\n\n");
    exit(1);
  }

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<p>
First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>.

<p>Then we're going to find the number of logical bitstreams in the physical bitstream using <a href="ov_streams.html">ov_streams</a>.

<p>We use <a href="ov_time_total.html">ov_time_total</a> to determine the total length of the physical bitstream.  We specify that we want the entire bitstream by using the argument <tt>-1</tt>.

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  if(ov_seekable(&ov)){
    printf("Input bitstream contained %ld logical bitstream section(s).\n",
	   ov_streams(&ov));
    printf("Total bitstream playing time: %ld seconds\n\n",
	   (long)ov_time_total(&ov,-1));

  }else{
    printf("Standard input was not seekable.\n"
	   "First logical bitstream information:\n\n");
  }
  
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<p>Now we're going to iterate through each logical bitstream and print information about that bitstream.

<p>We use <a href="ov_info.html">ov_info</a> to pull out the <a href="vorbis_info.html">vorbis_info</a> struct for each logical bitstream.  This struct contains bitstream-specific info.

<p><a href="ov_serialnumber.html">ov_serialnumber</a> retrieves the unique serial number for the logical bistream.  <a href="ov_raw_total.html">ov_raw_total</a> gives the total compressed bytes for the logical bitstream, and <a href="ov_time_total.html">ov_time_total</a> gives the total time in the logical bitstream.

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  for(i=0;i<ov_streams(&ov);i++){
    vorbis_info *vi=ov_info(&ov,i);
    printf("\tlogical bitstream section %d information:\n",i+1);
    printf("\t\t%ldHz %d channels bitrate %ldkbps serial number=%ld\n",
	   vi->rate,vi->channels,ov_bitrate(&ov,i)/1000,
	   ov_serialnumber(&ov,i));
    printf("\t\tcompressed length: %ld bytes ",(long)(ov_raw_total(&ov,i)));
    printf(" play time: %lds\n",(long)ov_time_total(&ov,i));
  } 
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<p>
When we're done with the entire physical bitstream, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream.

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  ov_clear(&ov);
  return 0;
}
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<p>
The full source for chaining_example.c can be found with the vorbis
distribution in <a href="chaining_example_c.html">chaining_example.c</a>.

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<td><p class=tiny>copyright &copy; 2000 vorbis team</p></td>
<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a><br><a href="mailto:team@vorbis.org">team@vorbis.org</a></p></td>
</tr><tr>
<td><p class=tiny>vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.25 - 20000615</p></td>
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</table>

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