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| <title>libogg - Decoding</title> |
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| <td><p class=tiny>libogg documentation</p></td> |
| <td align=right><p class=tiny>libogg release 1.3.0 - 20110804</p></td> |
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| <h1>Decoding</h1> |
| <p>Libogg contains a set of functions used in the decoding process. |
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| All the <b>libogg</b> specific functions are declared in "ogg/ogg.h". |
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| <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. |
| <p>Decoding through the Ogg layer follows a specific logical sequence. A read loop follows these logical steps: |
| <ul> |
| <li>Expose a buffer using <a href="ogg_sync_buffer.html">ogg_sync_buffer()</a>. |
| <li>Read data into the buffer, using fread() or a similar function. |
| <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. |
| <li>Write out the data using <a href="ogg_sync_pageout.html">ogg_sync_pageout</a>. |
| <li>Submit the completed page to the streaming layer with <a href="ogg_stream_pagein.html">ogg_stream_pagein</a>. |
| <li>Output a packet of data to the codec-specific decoding layer using <a href="ogg_stream_packetout.html">ogg_stream_packetout</a>. |
| </ul> |
| <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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| <table border=1 color=black width=50% cellspacing=0 cellpadding=7> |
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| <td><b>function</b></td> |
| <td><b>purpose</b></td> |
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| <tr valign=top> |
| <td><a href="ogg_sync_init.html">ogg_sync_init</a></td> |
| <td>Initializes an Ogg bitstream.</td> |
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| <td><a href="ogg_sync_clear.html">ogg_sync_clear</a></td> |
| <td>Clears the status information from the synchronization struct.<td> |
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| <td><a href="ogg_sync_reset.html">ogg_sync_reset</a></td> |
| <td>Resets the synchronization status to initial values.</td> |
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| <td><a href="ogg_sync_destroy.html">ogg_sync_destroy</a></td> |
| <td>Frees the synchronization struct.</td> |
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| <td><a href="ogg_sync_check.html">ogg_sync_check</a></td> |
| <td>Check for asynchronous errors.</td> |
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| <td><a href="ogg_sync_buffer.html">ogg_sync_buffer</a></td> |
| <td>Exposes a buffer from the synchronization layer in order to read data.</td> |
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| <td><a href="ogg_sync_wrote.html">ogg_sync_wrote</a></td> |
| <td>Tells the synchronization layer how many bytes were written into the buffer.</td> |
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| <td><a href="ogg_sync_pageseek.html">ogg_sync_pageseek</a></td> |
| <td>Finds the borders of pages and resynchronizes the stream.</td> |
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| <td><a href="ogg_sync_pageout.html">ogg_sync_pageout</a></td> |
| <td>Outputs a page from the synchronization layer.</td> |
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| <td><a href="ogg_stream_pagein.html">ogg_stream_pagein</a></td> |
| <td>Submits a complete page to the stream layer.</td> |
| </tr> |
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| <td><a href="ogg_stream_packetout.html">ogg_stream_packetout</a></td> |
| <td>Outputs a packet to the codec-specific decoding engine.</td> |
| </tr> |
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| <td><a href="ogg_stream_packetpeek.html">ogg_stream_packetpeek</a></td> |
| <td>Provides access to the next packet in the bitstream without |
| advancing decoding.</td> |
| </tr> |
| </table> |
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| <br><br> |
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| <td><p class=tiny>copyright © 2000-2011 Xiph.Org</p></td> |
| <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/">Ogg Container Format</a></p></td> |
| </tr><tr> |
| <td><p class=tiny>libogg documentation</p></td> |
| <td align=right><p class=tiny>libogg release 1.3.0 - 20110804</p></td> |
| </tr> |
| </table> |
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