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Bring in flac, ogg, vorbis
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Mar 2013 17:37:49 +0000
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cannam@86 1 <html>
cannam@86 2
cannam@86 3 <head>
cannam@86 4 <title>libvorbisenc - Documentation</title>
cannam@86 5 <link rel=stylesheet href="style.css" type="text/css">
cannam@86 6 </head>
cannam@86 7
cannam@86 8 <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
cannam@86 9 <table border=0 width=100%>
cannam@86 10 <tr>
cannam@86 11 <td><p class=tiny>libvorbisenc documentation</p></td>
cannam@86 12 <td align=right><p class=tiny>libvorbisenc version 1.3.2 - 20101101</p></td>
cannam@86 13 </tr>
cannam@86 14 </table>
cannam@86 15
cannam@86 16 <h1>Libvorbisenc Setup Examples</h1>
cannam@86 17
cannam@86 18 VBR is always the recommended mode for Vorbis encoding when
cannam@86 19 there's no need to impose bitrate constraints. True VBR encoding will
cannam@86 20 always produce the most consistent quality output as well as the
cannam@86 21 highest quality for a the bits used.
cannam@86 22
cannam@86 23 <p>The following code examples prepare a
cannam@86 24 <a href="../libvorbis/vorbis_info.html">vorbis_info</a> structure for encoding
cannam@86 25 use with libvorbis.<p>
cannam@86 26
cannam@86 27 <h2>Example: encoding using a VBR quality mode</h2>
cannam@86 28
cannam@86 29 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
cannam@86 30 <tr bgcolor=#cccccc><td><pre><b>
cannam@86 31 vorbis_info_init(&vi);
cannam@86 32
cannam@86 33 /*********************************************************************
cannam@86 34 Encoding using a VBR quality mode. The usable range is -.1
cannam@86 35 (lowest quality, smallest file) to 1.0 (highest quality, largest file).
cannam@86 36 Example quality mode .4: 44kHz stereo coupled, roughly 128kbps VBR
cannam@86 37 *********************************************************************/
cannam@86 38
cannam@86 39 ret = vorbis_encode_init_vbr(&vi,2,44100,.4);
cannam@86 40
cannam@86 41 /*********************************************************************
cannam@86 42 do not continue if setup failed; this can happen if we ask for a
cannam@86 43 mode that libVorbis does not support (eg, too low a quality mode, etc,
cannam@86 44 will return 'OV_EIMPL')
cannam@86 45 *********************************************************************/
cannam@86 46
cannam@86 47 if(ret) exit(1);
cannam@86 48 </b></pre></td></tr></table>
cannam@86 49
cannam@86 50 <h2>Example: encoding using average bitrate (ABR)</h2>
cannam@86 51
cannam@86 52 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
cannam@86 53 <tr bgcolor=#cccccc><td><pre><b>
cannam@86 54 vorbis_info_init(&vi);
cannam@86 55
cannam@86 56 /*********************************************************************
cannam@86 57 Encoding using an average bitrate mode (ABR).
cannam@86 58 example: 44kHz stereo coupled, average 128kbps ABR
cannam@86 59 *********************************************************************/
cannam@86 60
cannam@86 61 ret = vorbis_encode_init(&vi,2,44100,-1,128000,-1);
cannam@86 62
cannam@86 63 /*********************************************************************
cannam@86 64 do not continue if setup failed; this can happen if we ask for a
cannam@86 65 mode that libVorbis does not support (eg, too low a bitrate, etc,
cannam@86 66 will return 'OV_EIMPL')
cannam@86 67 *********************************************************************/
cannam@86 68
cannam@86 69 if(ret) exit(1);
cannam@86 70 </b></pre></td></tr></table>
cannam@86 71
cannam@86 72 <h2>Example: encoding using constant bitrate (CBR)</h2>
cannam@86 73
cannam@86 74 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
cannam@86 75 <tr bgcolor=#cccccc><td><pre><b>
cannam@86 76 vorbis_info_init(&vi);
cannam@86 77
cannam@86 78 /*********************************************************************
cannam@86 79 Encoding using a constant bitrate mode (CBR).
cannam@86 80 example: 44kHz stereo coupled, average 128kbps CBR
cannam@86 81 *********************************************************************/
cannam@86 82
cannam@86 83 ret = vorbis_encode_init(&vi,2,44100,128000,128000,128000);
cannam@86 84
cannam@86 85 /*********************************************************************
cannam@86 86 do not continue if setup failed; this can happen if we ask for a
cannam@86 87 mode that libVorbis does not support (eg, too low a bitrate, etc,
cannam@86 88 will return 'OV_EIMPL')
cannam@86 89 *********************************************************************/
cannam@86 90
cannam@86 91 if(ret) exit(1);
cannam@86 92 </b></pre></td></tr></table>
cannam@86 93
cannam@86 94 <h2>Example: encoding using VBR selected by approximate bitrate</h2>
cannam@86 95
cannam@86 96 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
cannam@86 97 <tr bgcolor=#cccccc><td><pre><b>
cannam@86 98 vorbis_info_init(&vi);
cannam@86 99
cannam@86 100 /*********************************************************************
cannam@86 101 Encode using a quality mode, but select that quality mode by asking for
cannam@86 102 an approximate bitrate. This is not ABR, it is true VBR, but selected
cannam@86 103 using the bitrate interface, and then turning bitrate management off:
cannam@86 104 *********************************************************************/
cannam@86 105
cannam@86 106 ret = ( vorbis_encode_setup_managed(&vi,2,44100,-1,128000,-1) ||
cannam@86 107 vorbis_encode_ctl(&vi,OV_ECTL_RATEMANAGE2_SET,NULL) ||
cannam@86 108 vorbis_encode_setup_init(&vi));
cannam@86 109
cannam@86 110 /*********************************************************************
cannam@86 111 do not continue if setup failed; this can happen if we ask for a
cannam@86 112 mode that libVorbis does not support (eg, too low a bitrate, etc,
cannam@86 113 will return 'OV_EIMPL')
cannam@86 114 *********************************************************************/
cannam@86 115
cannam@86 116 if(ret) exit(1);
cannam@86 117 </b></pre></td></tr></table>
cannam@86 118
cannam@86 119 <br><br>
cannam@86 120 <hr noshade>
cannam@86 121 <table border=0 width=100%>
cannam@86 122 <tr valign=top>
cannam@86 123 <td><p class=tiny>copyright &copy; 2000-2010 Xiph.Org</p></td>
cannam@86 124 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
cannam@86 125 </tr><tr>
cannam@86 126 <td><p class=tiny>libvorbisenc documentation</p></td>
cannam@86 127 <td align=right><p class=tiny>libvorbisenc version 1.3.2 - 20101101</p></td>
cannam@86 128 </tr>
cannam@86 129 </table>
cannam@86 130
cannam@86 131 </body>
cannam@86 132
cannam@86 133 </html>