1 <html> 2 3 <head> 4 <title>libvorbisenc - Documentation</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>libvorbisenc documentation</p></td> 12 <td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td> 13 </tr> 14 </table> 15 16 <h1>Libvorbisenc Setup Examples</h1> 17 18 VBR is always the recommended mode for Vorbis encoding when 19 there's no need to impose bitrate constraints. True VBR encoding will 20 always produce the most consistent quality output as well as the 21 highest quality for a the bits used. 22 23 <p>The following code examples prepare a 24 <a href="vorbis_info.html">vorbis_info</a> structure for encoding 25 use with libvorbis.<p> 26 27 <h2>Example: encoding using a VBR quality mode</h2> 28 29 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 30 <tr bgcolor=#cccccc><td><pre><b> 31 vorbis_info_init(&vi); 32 33 /********************************************************************* 34 Encoding using a VBR quality mode. The usable range is -.1 35 (lowest quality, smallest file) to 1.0 (highest quality, largest file). 36 Example quality mode .4: 44kHz stereo coupled, roughly 128kbps VBR 37 *********************************************************************/ 38 39 ret = vorbis_encode_init_vbr(&vi,2,44100,.4); 40 41 /********************************************************************* 42 do not continue if setup failed; this can happen if we ask for a 43 mode that libVorbis does not support (eg, too low a quality mode, etc, 44 will return 'OV_EIMPL') 45 *********************************************************************/ 46 47 if(ret) exit(1); 48 </b></pre></td></tr></table> 49 50 <h2>Example: encoding using average bitrate (ABR)</h2> 51 52 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 53 <tr bgcolor=#cccccc><td><pre><b> 54 vorbis_info_init(&vi); 55 56 /********************************************************************* 57 Encoding using an average bitrate mode (ABR). 58 example: 44kHz stereo coupled, average 128kbps ABR 59 *********************************************************************/ 60 61 ret = vorbis_encode_init(&vi,2,44100,-1,128000,-1); 62 63 /********************************************************************* 64 do not continue if setup failed; this can happen if we ask for a 65 mode that libVorbis does not support (eg, too low a bitrate, etc, 66 will return 'OV_EIMPL') 67 *********************************************************************/ 68 69 if(ret) exit(1); 70 </b></pre></td></tr></table> 71 72 <h2>Example: encoding using constant bitrate (CBR)</h2> 73 74 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 75 <tr bgcolor=#cccccc><td><pre><b> 76 vorbis_info_init(&vi); 77 78 /********************************************************************* 79 Encoding using a constant bitrate mode (CBR). 80 example: 44kHz stereo coupled, average 128kbps CBR 81 *********************************************************************/ 82 83 ret = vorbis_encode_init(&vi,2,44100,128000,128000,128000); 84 85 /********************************************************************* 86 do not continue if setup failed; this can happen if we ask for a 87 mode that libVorbis does not support (eg, too low a bitrate, etc, 88 will return 'OV_EIMPL') 89 *********************************************************************/ 90 91 if(ret) exit(1); 92 </b></pre></td></tr></table> 93 94 <h2>Example: encoding using VBR selected by approximate bitrate</h2> 95 96 <table border=0 width=100% color=black cellspacing=0 cellpadding=7> 97 <tr bgcolor=#cccccc><td><pre><b> 98 vorbis_info_init(&vi); 99 100 /********************************************************************* 101 Encode using a quality mode, but select that quality mode by asking for 102 an approximate bitrate. This is not ABR, it is true VBR, but selected 103 using the bitrate interface, and then turning bitrate management off: 104 *********************************************************************/ 105 106 ret = ( vorbis_encode_setup_managed(&vi,2,44100,-1,128000,-1) || 107 vorbis_encode_ctl(&vi,OV_ECTL_RATEMANAGE2_SET,NULL) || 108 vorbis_encode_setup_init(&vi)); 109 110 /********************************************************************* 111 do not continue if setup failed; this can happen if we ask for a 112 mode that libVorbis does not support (eg, too low a bitrate, etc, 113 will return 'OV_EIMPL') 114 *********************************************************************/ 115 116 if(ret) exit(1); 117 </b></pre></td></tr></table> 118 119 <br><br> 120 <hr noshade> 121 <table border=0 width=100%> 122 <tr valign=top> 123 <td><p class=tiny>copyright © 2000-2004 vorbis team</p></td> 124 <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> 125 </tr><tr> 126 <td><p class=tiny>libvorbisenc documentation</p></td> 127 <td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td> 128 </tr> 129 </table> 130 131 </body> 132 133 </html> 134
