layer2.source"><code>MediaPeriod</code></a> identified by <code>periodId</code>.

 <p>Should not be called directly from application code.

 <p>This method must be called on the playback thread and only if the source is enabled.</div>
<dl>
<dt><span class="paramLabel">Parameters:</span></dt>
<dd><code>id</code> - The identifier of the period.</dd>
<dd><code>allocator</code> - An <a href="../../upstream/Allocator.html" title="interface in com.google.android.exoplayer2.upstream"><code>Allocator</code></a> fro