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1 <html>
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3 <head>
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4 <title>libvorbis - function - vorbis_analysis</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>libvorbis documentation</p></td>
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12 <td align=right><p class=tiny>libvorbis 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>vorbis_analysis</h1>
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17
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18 <p><i>declared in "vorbis/codec.h";</i></p>
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19
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20 <p>Once the uncompressed audio data has been divided into blocks, this
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21 function is called on each block. It looks up the encoding mode and
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22 dispatches the block to the forward transform provided by that mode.
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23 </p>
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24 <p>When using a basic encoding mode, with no bitrate management,
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25 an ogg_packet pointer can be given, and the coded block is returned
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26 directly through that structure and can be placed in the output stream.
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27 </p>
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28 <p>Otherwise, NULL should be passed for the ogg_packet pointer. In
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29 that case, after the transform has been applied, the block must passed
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30 to vorbis_bitrate_addblock() for further coding. This method works with
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31 both basic and managed encoding modes, so it's recommended for new code.
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32 </p>
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33
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34 <table border=0 color=black cellspacing=0 cellpadding=7>
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35 <tr bgcolor=#cccccc>
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36 <td>
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37 <pre><b>
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38 extern int vorbis_analysis(vorbis_block *vb,ogg_packet *op);
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39 </b></pre>
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40 </td>
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41 </tr>
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42 </table>
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43
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44 <h3>Parameters</h3>
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45 <dl>
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46 <dt><i>vb</i></dt>
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47 <dd>Pointer to the vorbis_block to be encoded.</dd>
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48 <dt><i>op</i></dt>
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49 <dd>Optional pointer to an ogg_packet. This is normally NULL,
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50 and the final output is obtained by passing <i>vb</i> though the
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51 vorbis_bitrate_*() interface to perform further refinement.
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52 However, when not using a bitrate managed encoding mode, it
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53 is possible to skip that step by providing an ogg_packet pointer
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54 here, obtaining the compressed data directly.</dd>
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55 </dl>
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56
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57
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58 <h3>Return Values</h3>
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59 <ul>
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60 <li>0 for success</li>
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61 <li>negative values for failure:
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62 <ul>
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63 <li>OV_EINVAL - Invalid request; a non-NULL value was passed for <i>op</i> when the encoder is using a bitrate managed mode.</li>
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64 <li>OV_EFAULT - Internal fault; indicates a bug or memory corruption.</li>
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65 <li>OV_EIMPL - Unimplemented; not supported by this version of the library.</li>
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66 </ul>
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67 </li>
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68 </ul>
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69 <p>
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70
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71 <br><br>
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72 <hr noshade>
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73 <table border=0 width=100%>
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74 <tr valign=top>
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75 <td><p class=tiny>copyright © 2010 Xiph.Org</p></td>
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76 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/index.html">Ogg Vorbis</a></p></td>
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77 </tr><tr>
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78 <td><p class=tiny>libvorbis documentation</p></td>
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79 <td align=right><p class=tiny>libvorbis version 1.3.2 - 20101101</p></td>
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80 </tr>
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81 </table>
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82
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83
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84 </body>
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85
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86 </html>
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