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<h1><a class="anchor" id="granule">Granule encoding </a></h1><p>Ogg leaves the encoding of granules up to a particular codec, only mandating that granules be non decreasing with time.</p>
<p>The Kate bitstream format uses a linear mapping between time and granule, described here.</p>
<p>A Kate granule position is composed of two different parts:</p>
<ul>
<li>a base granule, in the high bits</li>
<li>a granule offset, in the low bits</li>
</ul>
<div class="fragment"><pre class="fragment">
+----------------+----------------+
| base | offset |
+----------------+----------------+
</pre></div><p>The number of bits these parts occupy is variable, and each stream may choose how many bits to dedicate to each. The <a class="el" href="structkate__info.html">kate_info</a> structure for a stream holds that information in the granule_shift field, so each part may be reconstructed from a granulepos.</p>
<p>The <a class="el" href="structkate__info.html">kate_info</a> structure for a stream also holds a rational fraction representing the time span of granule units.</p>
<p>The granule rate is defined by the two fields: </p>
<div class="fragment"><pre class="fragment"><a class="code" href="structkate__info.html#a7eb196702d96e5676b27838cadfd6acf">kate_info::gps_numerator</a>
<a class="code" href="structkate__info.html#a00c2253966d5a22cc3e56f4f98dd4995">kate_info::gps_denominator</a>
</pre></div><p>The number of bits reserved for the offset is defined by the field: </p>
<div class="fragment"><pre class="fragment"><a class="code" href="structkate__info.html#a1bf457732577344fa6d0f035d30d1e13">kate_info::granule_shift</a>
</pre></div> </div>
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