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| 4 | <title>libvorbisenc - Documentation</title>
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| 5 | <link rel=stylesheet href="style.css" type="text/css">
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| 6 | </head>
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| 7 |
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| 8 | <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
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| 9 | <table border=0 width=100%>
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| 10 | <tr>
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| 11 | <td><p class=tiny>libvorbisenc documentation</p></td>
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| 12 | <td align=right><p class=tiny>libvorbisenc version 1.3.2 - 20101101</p></td>
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| 13 | </tr>
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| 14 | </table>
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| 15 |
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| 16 | <h1>Libvorbisenc Setup Examples</h1>
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| 17 |
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| 18 | VBR is always the recommended mode for Vorbis encoding when
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| 19 | there's no need to impose bitrate constraints. True VBR encoding will
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| 20 | always produce the most consistent quality output as well as the
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| 21 | highest quality for a the bits used.
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| 22 |
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| 23 | <p>The following code examples prepare a
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| 24 | <a href="../libvorbis/vorbis_info.html">vorbis_info</a> structure for encoding
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| 25 | use with libvorbis.<p>
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| 26 |
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| 27 | <h2>Example: encoding using a VBR quality mode</h2>
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| 28 |
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| 29 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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| 30 | <tr bgcolor=#cccccc><td><pre><b>
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| 31 | vorbis_info_init(&vi);
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| 32 |
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| 33 | /*********************************************************************
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| 34 | Encoding using a VBR quality mode. The usable range is -.1
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| 35 | (lowest quality, smallest file) to 1.0 (highest quality, largest file).
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| 36 | Example quality mode .4: 44kHz stereo coupled, roughly 128kbps VBR
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| 37 | *********************************************************************/
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| 38 |
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| 39 | ret = vorbis_encode_init_vbr(&vi,2,44100,.4);
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| 40 |
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| 41 | /*********************************************************************
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| 42 | do not continue if setup failed; this can happen if we ask for a
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| 43 | mode that libVorbis does not support (eg, too low a quality mode, etc,
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| 44 | will return 'OV_EIMPL')
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| 45 | *********************************************************************/
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| 46 |
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| 47 | if(ret) exit(1);
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| 48 | </b></pre></td></tr></table>
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| 49 |
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| 50 | <h2>Example: encoding using average bitrate (ABR)</h2>
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| 51 |
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| 52 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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| 53 | <tr bgcolor=#cccccc><td><pre><b>
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| 54 | vorbis_info_init(&vi);
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| 55 |
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| 56 | /*********************************************************************
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| 57 | Encoding using an average bitrate mode (ABR).
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| 58 | example: 44kHz stereo coupled, average 128kbps ABR
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| 59 | *********************************************************************/
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| 60 |
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| 61 | ret = vorbis_encode_init(&vi,2,44100,-1,128000,-1);
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| 62 |
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| 63 | /*********************************************************************
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| 64 | do not continue if setup failed; this can happen if we ask for a
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| 65 | mode that libVorbis does not support (eg, too low a bitrate, etc,
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| 66 | will return 'OV_EIMPL')
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| 67 | *********************************************************************/
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| 68 |
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| 69 | if(ret) exit(1);
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| 70 | </b></pre></td></tr></table>
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| 71 |
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| 72 | <h2>Example: encoding using constant bitrate (CBR)</h2>
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| 73 |
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| 74 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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| 75 | <tr bgcolor=#cccccc><td><pre><b>
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| 76 | vorbis_info_init(&vi);
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| 77 |
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| 78 | /*********************************************************************
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| 79 | Encoding using a constant bitrate mode (CBR).
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| 80 | example: 44kHz stereo coupled, average 128kbps CBR
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| 81 | *********************************************************************/
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| 82 |
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| 83 | ret = vorbis_encode_init(&vi,2,44100,128000,128000,128000);
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| 84 |
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| 85 | /*********************************************************************
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| 86 | do not continue if setup failed; this can happen if we ask for a
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| 87 | mode that libVorbis does not support (eg, too low a bitrate, etc,
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| 88 | will return 'OV_EIMPL')
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| 89 | *********************************************************************/
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| 90 |
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| 91 | if(ret) exit(1);
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| 92 | </b></pre></td></tr></table>
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| 93 |
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| 94 | <h2>Example: encoding using VBR selected by approximate bitrate</h2>
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| 95 |
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| 96 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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| 97 | <tr bgcolor=#cccccc><td><pre><b>
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| 98 | vorbis_info_init(&vi);
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| 99 |
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| 100 | /*********************************************************************
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| 101 | Encode using a quality mode, but select that quality mode by asking for
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| 102 | an approximate bitrate. This is not ABR, it is true VBR, but selected
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| 103 | using the bitrate interface, and then turning bitrate management off:
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| 104 | *********************************************************************/
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| 105 |
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| 106 | ret = ( vorbis_encode_setup_managed(&vi,2,44100,-1,128000,-1) ||
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| 107 | vorbis_encode_ctl(&vi,OV_ECTL_RATEMANAGE2_SET,NULL) ||
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| 108 | vorbis_encode_setup_init(&vi));
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| 109 |
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| 110 | /*********************************************************************
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| 111 | do not continue if setup failed; this can happen if we ask for a
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| 112 | mode that libVorbis does not support (eg, too low a bitrate, etc,
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| 113 | will return 'OV_EIMPL')
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| 114 | *********************************************************************/
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| 115 |
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| 116 | if(ret) exit(1);
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| 117 | </b></pre></td></tr></table>
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| 118 |
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| 119 | <br><br>
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| 120 | <hr noshade>
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| 121 | <table border=0 width=100%>
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| 122 | <tr valign=top>
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| 123 | <td><p class=tiny>copyright © 2000-2010 Xiph.Org</p></td>
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| 124 | <td align=right><p class=tiny><a href="https://xiph.org/vorbis/">Ogg Vorbis</a></p></td>
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| 125 | </tr><tr>
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| 126 | <td><p class=tiny>libvorbisenc documentation</p></td>
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| 127 | <td align=right><p class=tiny>libvorbisenc version 1.3.2 - 20101101</p></td>
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| 128 | </tr>
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| 129 | </table>
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| 130 |
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| 131 | </body>
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| 132 |
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| 133 | </html>
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