| <html> |
| |
| <head> |
| <title>libvorbisenc - Documentation</title> |
| <link rel=stylesheet href="style.css" type="text/css"> |
| </head> |
| |
| <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> |
| <table border=0 width=100%> |
| <tr> |
| <td><p class=tiny>libvorbisenc documentation</p></td> |
| <td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td> |
| </tr> |
| </table> |
| |
| <h1>Libvorbisenc Setup Examples</h1> |
| |
| VBR is always the recommended mode for Vorbis encoding when |
| there's no need to impose bitrate constraints. True VBR encoding will |
| always produce the most consistent quality output as well as the |
| highest quality for a the bits used. |
| |
| <p>The following code examples prepare a |
| <a href="vorbis_info.html">vorbis_info</a> structure for encoding |
| use with libvorbis.<p> |
| |
| <h2>Example: encoding using a VBR quality mode</h2> |
| |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc><td><pre><b> |
| vorbis_info_init(&vi); |
| |
| /********************************************************************* |
| Encoding using a VBR quality mode. The usable range is -.1 |
| (lowest quality, smallest file) to 1.0 (highest quality, largest file). |
| Example quality mode .4: 44kHz stereo coupled, roughly 128kbps VBR |
| *********************************************************************/ |
| |
| ret = vorbis_encode_init_vbr(&vi,2,44100,.4); |
| |
| /********************************************************************* |
| do not continue if setup failed; this can happen if we ask for a |
| mode that libVorbis does not support (eg, too low a quality mode, etc, |
| will return 'OV_EIMPL') |
| *********************************************************************/ |
| |
| if(ret) exit(1); |
| </b></pre></td></tr></table> |
| |
| <h2>Example: encoding using average bitrate (ABR)</h2> |
| |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc><td><pre><b> |
| vorbis_info_init(&vi); |
| |
| /********************************************************************* |
| Encoding using an average bitrate mode (ABR). |
| example: 44kHz stereo coupled, average 128kbps ABR |
| *********************************************************************/ |
| |
| ret = vorbis_encode_init(&vi,2,44100,-1,128000,-1); |
| |
| /********************************************************************* |
| do not continue if setup failed; this can happen if we ask for a |
| mode that libVorbis does not support (eg, too low a bitrate, etc, |
| will return 'OV_EIMPL') |
| *********************************************************************/ |
| |
| if(ret) exit(1); |
| </b></pre></td></tr></table> |
| |
| <h2>Example: encoding using constant bitrate (CBR)</h2> |
| |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc><td><pre><b> |
| vorbis_info_init(&vi); |
| |
| /********************************************************************* |
| Encoding using a constant bitrate mode (CBR). |
| example: 44kHz stereo coupled, average 128kbps CBR |
| *********************************************************************/ |
| |
| ret = vorbis_encode_init(&vi,2,44100,128000,128000,128000); |
| |
| /********************************************************************* |
| do not continue if setup failed; this can happen if we ask for a |
| mode that libVorbis does not support (eg, too low a bitrate, etc, |
| will return 'OV_EIMPL') |
| *********************************************************************/ |
| |
| if(ret) exit(1); |
| </b></pre></td></tr></table> |
| |
| <h2>Example: encoding using VBR selected by approximate bitrate</h2> |
| |
| <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
| <tr bgcolor=#cccccc><td><pre><b> |
| vorbis_info_init(&vi); |
| |
| /********************************************************************* |
| Encode using a quality mode, but select that quality mode by asking for |
| an approximate bitrate. This is not ABR, it is true VBR, but selected |
| using the bitrate interface, and then turning bitrate management off: |
| *********************************************************************/ |
| |
| ret = ( vorbis_encode_setup_managed(&vi,2,44100,-1,128000,-1) || |
| vorbis_encode_ctl(&vi,OV_ECTL_RATEMANAGE2_SET,NULL) || |
| vorbis_encode_setup_init(&vi)); |
| |
| /********************************************************************* |
| do not continue if setup failed; this can happen if we ask for a |
| mode that libVorbis does not support (eg, too low a bitrate, etc, |
| will return 'OV_EIMPL') |
| *********************************************************************/ |
| |
| if(ret) exit(1); |
| </b></pre></td></tr></table> |
| |
| <br><br> |
| <hr noshade> |
| <table border=0 width=100%> |
| <tr valign=top> |
| <td><p class=tiny>copyright © 2000-2004 vorbis team</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>libvorbisenc documentation</p></td> |
| <td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td> |
| </tr> |
| </table> |
| |
| </body> |
| |
| </html> |