1 <html> 2 3 <head> 4 <title>vorbisfile - Example Code</title> 5 <link rel=stylesheet href="style.css" type="text/css"> 6 </head> 7 8 <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> 9 <table border=0 width=100%> 10 <tr> 11 <td><p class=tiny>Vorbisfile documentation</p></td> 12 <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> 13 </tr> 14 </table> 15 16 <h1>Chaining Example Code</h1> 17 18 <p> 19 The following is a run-through of the chaining example program supplied 20 with vorbisfile - <a href="chaining_example_c.html">chaining_example.c</a>. 21 This program demonstrates how to work with a chained bitstream. 22 23 <p> 24 First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included. 25 26 <br><br> 27 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 28 <tr bgcolor=#cccccc> 29 <td> 30 <pre><b> 31 #include "vorbis/codec.h" 32 #include "vorbis/vorbisfile.h" 33 #include "../lib/misc.h" 34 </b></pre> 35 </td> 36 </tr> 37 </table> 38 39 <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare a other helpful variables to track our progress within the file. 40 <br><br> 41 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 42 <tr bgcolor=#cccccc> 43 <td> 44 <pre><b> 45 int main(){ 46 OggVorbis_File ov; 47 int i; 48 </b></pre> 49 </td> 50 </tr> 51 </table> 52 53 <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. 54 <br><br> 55 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 56 <tr bgcolor=#cccccc> 57 <td> 58 <pre><b> 59 #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */ 60 _setmode( _fileno( stdin ), _O_BINARY ); 61 #endif 62 </b></pre> 63 </td> 64 </tr> 65 </table> 66 67 <p>We call <a href="ov_open_callbacks.html">ov_open_callbacks()</a> to 68 initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> 69 structure. <a href="ov_open_callbacks.html">ov_open_callbacks()</a> 70 also checks to ensure that we're reading Vorbis format and not 71 something else. The OV_CALLBACKS_NOCLOSE callbacks instruct 72 libvorbisfile not to close stdin later during cleanup.<p> 73 74 <br><br> 75 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 76 <tr bgcolor=#cccccc> 77 <td> 78 <pre><b> 79 if(ov_open_callbacks(stdin,&ov,NULL,-1,OV_CALLBACKS_NOCLOSE)<0){ 80 printf("Could not open input as an OggVorbis file.\n\n"); 81 exit(1); 82 } 83 84 </b></pre> 85 </td> 86 </tr> 87 </table> 88 89 <p> 90 First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>. 91 92 <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>. 93 94 <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>. 95 96 <br><br> 97 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 98 <tr bgcolor=#cccccc> 99 <td> 100 <pre><b> 101 if(ov_seekable(&ov)){ 102 printf("Input bitstream contained %ld logical bitstream section(s).\n", 103 ov_streams(&ov)); 104 printf("Total bitstream playing time: %ld seconds\n\n", 105 (long)ov_time_total(&ov,-1)); 106 107 }else{ 108 printf("Standard input was not seekable.\n" 109 "First logical bitstream information:\n\n"); 110 } 111 112 </b></pre> 113 </td> 114 </tr> 115 </table> 116 117 <p>Now we're going to iterate through each logical bitstream and print information about that bitstream. 118 119 <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. 120 121 <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. 122 123 <br><br> 124 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 125 <tr bgcolor=#cccccc> 126 <td> 127 <pre><b> 128 for(i=0;i<ov_streams(&ov);i++){ 129 vorbis_info *vi=ov_info(&ov,i); 130 printf("\tlogical bitstream section %d information:\n",i+1); 131 printf("\t\t%ldHz %d channels bitrate %ldkbps serial number=%ld\n", 132 vi->rate,vi->channels,ov_bitrate(&ov,i)/1000, 133 ov_serialnumber(&ov,i)); 134 printf("\t\tcompressed length: %ld bytes ",(long)(ov_raw_total(&ov,i))); 135 printf(" play time: %lds\n",(long)ov_time_total(&ov,i)); 136 } 137 </b></pre> 138 </td> 139 </tr> 140 </table> 141 <p> 142 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. 143 144 <br><br> 145 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 146 <tr bgcolor=#cccccc> 147 <td> 148 <pre><b> 149 ov_clear(&ov); 150 return 0; 151 } 152 </b></pre> 153 </td> 154 </tr> 155 </table> 156 157 <p> 158 The full source for chaining_example.c can be found with the vorbis 159 distribution in <a href="chaining_example_c.html">chaining_example.c</a>. 160 161 <br><br> 162 <hr noshade> 163 <table border=0 width=100%> 164 <tr valign=top> 165 <td><p class=tiny>copyright © 2007 Xiph.org</p></td> 166 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a><br><a href="mailto:team (a] vorbis.org">team (a] vorbis.org</a></p></td> 167 </tr><tr> 168 <td><p class=tiny>Vorbisfile documentation</p></td> 169 <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> 170 </tr> 171 </table> 172 173 </body> 174 175 </html> 176
