/Code/Angel/Libraries/libogg-1.2.0/doc/libogg/decoding.html

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  4. <title>libogg - Decoding</title>
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  11. <td><p class=tiny>libogg documentation</p></td>
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  12. <td align=right><p class=tiny>libogg release 1.2.0 - 20100325</p></td>
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  15. 

  16. <h1>Decoding</h1>
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  17. <p>Libogg contains a set of functions used in the decoding process.
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  18. <p>
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  19. All the <b>libogg</b> specific functions are declared in "ogg/ogg.h".
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  20. <p>
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  21. <p>Decoding is based around the ogg synchronization layer.  The <a href="ogg_sync_state.html">ogg_sync_state</a> struct coordinates between incoming data and the decoder.  We read data into the synchronization layer, submit the data to the stream, and output raw packets to the decoder.
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  22. <p>Decoding through the Ogg layer follows a specific logical sequence.  A read loop follows these logical steps:
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  23. <ul>
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  24. <li>Expose a buffer using <a href="ogg_sync_buffer.html">ogg_sync_buffer()</a>.
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  25. <li>Read data into the buffer, using fread() or a similar function.
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  26. <li>Call <a href="ogg_sync_wrote.html">ogg_sync_wrote()</a> to tell the synchronization layer how many bytes you wrote into the buffer.
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  27. <li>Write out the data using <a href="ogg_sync_pageout.html">ogg_sync_pageout</a>.
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  28. <li>Submit the completed page to the streaming layer with <a href="ogg_stream_pagein.html">ogg_stream_pagein</a>.
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  29. <li>Output a packet of data to the codec-specific decoding layer using <a href="ogg_stream_packetout.html">ogg_stream_packetout</a>.
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  30. </ul>
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  31. <p>In practice, streams are more complex, and Ogg also must handle headers, incomplete or dropped pages, and other errors in input.
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  34. <table border=1 color=black width=50% cellspacing=0 cellpadding=7>
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  36. 	<td><b>function</b></td>
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  37. 	<td><b>purpose</b></td>
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  38. </tr>
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  40. <td><a href="ogg_sync_init.html">ogg_sync_init</a></td>
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  41. 	<td>Initializes an Ogg bitstream.</td>
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  44. <td><a href="ogg_sync_clear.html">ogg_sync_clear</a></td>
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  45. 	<td>Clears the status information from the synchronization struct.<td>
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  48. <td><a href="ogg_sync_reset.html">ogg_sync_reset</a></td>
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  49. 	<td>Resets the synchronization status to initial values.</td>
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  50. </tr>
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  52. <td><a href="ogg_sync_destroy.html">ogg_sync_destroy</a></td>
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  53. 	<td>Frees the synchronization struct.</td>
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  54. </tr>
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  56. <td><a href="ogg_sync_check.html">ogg_sync_check</a></td>
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  57. 	<td>Check for asynchronous errors.</td>
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  60. <td><a href="ogg_sync_buffer.html">ogg_sync_buffer</a></td>
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  61. 	<td>Exposes a buffer from the synchronization layer in order to read data.</td>
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  64. <td><a href="ogg_sync_wrote.html">ogg_sync_wrote</a></td>
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  65. 	<td>Tells the synchronization layer how many bytes were written into the buffer.</td>
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  66. </tr>
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  68. <td><a href="ogg_sync_pageseek.html">ogg_sync_pageseek</a></td>
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  69. 	<td>Finds the borders of pages and resynchronizes the stream.</td>
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  70. </tr>
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  72. <td><a href="ogg_sync_pageout.html">ogg_sync_pageout</a></td>
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  73. 	<td>Outputs a page from the synchronization layer.</td>
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  74. </tr>
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  75. <tr valign=top>
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  76. <td><a href="ogg_stream_pagein.html">ogg_stream_pagein</a></td>
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  77. 	<td>Submits a complete page to the stream layer.</td>
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  78. </tr>
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  79. <tr valign=top>
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  80. <td><a href="ogg_stream_packetout.html">ogg_stream_packetout</a></td>
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  81. 	<td>Outputs a packet to the codec-specific decoding engine.</td>
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  82. </tr>
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  83. <tr valign=top>
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  84. <td><a href="ogg_stream_packetpeek.html">ogg_stream_packetpeek</a></td>
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  85. 	<td>Provides access to the next packet in the bitstream without
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  86. advancing decoding.</td>
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  87. </tr>
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  88. </table>
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  90. <br><br>
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  91. <hr noshade>
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  92. <table border=0 width=100%>
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  94. <td><p class=tiny>copyright &copy; 2000-2010 Xiph.Org</p></td>
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  95. <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/">Ogg Container Format</a></p></td>
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  96. </tr><tr>
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  97. <td><p class=tiny>libogg documentation</p></td>
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  98. <td align=right><p class=tiny>libogg release 1.2.0 - 20100325</p></td>
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  99. </tr>
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  100. </table>
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  102. </body>
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  104. </html>
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