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| <title>vorbisfile - Example Code</title> |
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| <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> |
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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> |
| |
| <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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| <br><br> |
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| <pre><b> |
| #include "vorbis/codec.h" |
| #include "vorbis/vorbisfile.h" |
| #include "../lib/misc.h" |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| |
| <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare a other helpful variables to track our progress within the file. |
| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| <td> |
| <pre><b> |
| int main(){ |
| OggVorbis_File ov; |
| int i; |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| |
| <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. |
| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| <td> |
| <pre><b> |
| #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */ |
| _setmode( _fileno( stdin ), _O_BINARY ); |
| #endif |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| |
| <p>We call <a href="ov_open_callbacks.html">ov_open_callbacks()</a> to |
| initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> |
| structure. <a href="ov_open_callbacks.html">ov_open_callbacks()</a> |
| also checks to ensure that we're reading Vorbis format and not |
| something else. The OV_CALLBACKS_NOCLOSE callbacks instruct |
| libvorbisfile not to close stdin later during cleanup.<p> |
| |
| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc> |
| <td> |
| <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> |
| |
| <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>. |
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| <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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| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| <td> |
| <pre><b> |
| 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"); |
| } |
| |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| |
| <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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| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc> |
| <td> |
| <pre><b> |
| 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)); |
| } |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| <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. |
| |
| <br><br> |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc> |
| <td> |
| <pre><b> |
| ov_clear(&ov); |
| return 0; |
| } |
| </b></pre> |
| </td> |
| </tr> |
| </table> |
| |
| <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>. |
| |
| <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> |
