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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 1.2.0 - 20070723</p></td> |
| </tr> |
| </table> |
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| <h1>Example Code: seeking</h1> |
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| <p> |
| The following is a run-through of the seeking example program supplied |
| with vorbisfile - <a href="seeking_test_c.html">seeking_test.c</a>. |
| This program tests the vorbisfile <a href="ov_time_seek.html">ov_time_seek</a> function by seeking to random points within the file. |
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| <p> |
| First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included. |
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| <pre><b> |
| #include <stdlib.h> |
| #include <stdio.h> |
| #include "vorbis/codec.h" |
| #include "vorbis/vorbisfile.h" |
| </b></pre> |
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| |
| <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare other helpful variables to track our progress within the file. |
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| <pre><b> |
| int main(){ |
| OggVorbis_File ov; |
| int i; |
| </b></pre> |
| </td> |
| </tr> |
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| <p>This example takes its input on stdin which is in 'text' mode by default under Windows; this will corrupt the input data unless set to binary mode. This applies only to Windows. |
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| <pre><b> |
| #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */ |
| _setmode( _fileno( stdin ), _O_BINARY ); |
| #endif |
| </b></pre> |
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| </table> |
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| <p><a href="ov_open_callbacks.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_callbacks.html">ov_open_callbacks()</a> also checks to ensure that we're reading Vorbis format and not something else. |
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| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| <pre><b> |
| if(ov_open_callbacks(stdin,&ov,NULL,-1, OV_CALLBACKS_NOCLOSE)<0){ |
| printf("Could not open input as an OggVorbis file.\n\n"); |
| exit(1); |
| } |
| |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
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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 seek to 100 random spots in the bitstream using <a href="ov_time_seek.html">ov_time_seek</a> with randomly generated values. |
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| <br><br> |
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| <td> |
| <pre><b> |
| |
| /* print details about each logical bitstream in the input */ |
| if(ov_seekable(&ov)){ |
| double length=ov_time_total(&ov,-1); |
| printf("testing seeking to random places in %g seconds....\n",length); |
| for(i=0;i<100;i++){ |
| double val=(double)rand()/RAND_MAX*length; |
| ov_time_seek(&ov,val); |
| printf("\r\t%d [%gs]... ",i,val); |
| fflush(stdout); |
| } |
| |
| printf("\r \nOK.\n\n"); |
| }else{ |
| printf("Standard input was not seekable.\n"); |
| } |
| |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| <p> |
| When we're done seeking, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream. |
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| <br><br> |
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| <td> |
| <pre><b> |
| ov_clear(&ov); |
| return 0; |
| } |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
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| <p> |
| The full source for seeking_test.c can be found with the vorbis |
| distribution in <a href="seeking_test_c.html">seeking_test.c</a>. |
| |
| <br><br> |
| <hr noshade> |
| <table border=0 width=100%> |
| <tr valign=top> |
| <td><p class=tiny>copyright © 2007 Xiph.org</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 1.2.0 - 20070723</p></td> |
| </tr> |
| </table> |
| |
| </body> |
| |
| </html> |
