Moves the active speaker code.

src/main/java/org/jitsi/utils/dsi/AbstractActiveSpeakerDetector.java

@@ -0,0 +1,119 @@
+/*
+ * Copyright @ 2015 Atlassian Pty Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jitsi.utils.dsi;
+
+import java.util.*;
+
+/**
+ * Provides a base {@link ActiveSpeakerDetector} which aids the implementations
+ * of actual algorithms for the detection/identification of the active/dominant
+ * speaker in a multipoint conference.
+ *
+ * @author Boris Grozev
+ * @author Lyubomir Marinov
+ */
+public abstract class AbstractActiveSpeakerDetector
+    implements ActiveSpeakerDetector
+{
+    /**
+     * An empty array with element type <tt>ActiveSpeakerChangedListener</tt>.
+     * Explicitly defined for the purposes of reducing the total number of
+     * unnecessary allocations and the undesired effects of the garbage
+     * collector.
+     */
+    private static final ActiveSpeakerChangedListener[] NO_LISTENERS
+        = new ActiveSpeakerChangedListener[0];
+
+    /**
+     * The list of listeners to be notified by this detector when the active
+     * speaker changes.
+     */
+    private final List<ActiveSpeakerChangedListener> listeners
+        = new LinkedList<ActiveSpeakerChangedListener>();
+
+    /**
+     * {@inheritDoc}
+     *
+     * @throws NullPointerException if the specified <tt>listener</tt> is
+     * <tt>null</tt>
+     */
+    @Override
+    public void addActiveSpeakerChangedListener(
+            ActiveSpeakerChangedListener listener)
+    {
+        if (listener == null)
+            throw new NullPointerException("listener");
+
+        synchronized (listeners)
+        {
+            if (!listeners.contains(listener))
+                listeners.add(listener);
+        }
+    }
+
+    /**
+     * Notifies the <tt>ActiveSpeakerChangedListener</tt>s registered with this
+     * instance that the active speaker in multipoint conference associated with
+     * this instance has changed and is identified by a specific synchronization
+     * source identifier/SSRC.
+     *
+     * @param ssrc the synchronization source identifier/SSRC of the active
+     * speaker in the multipoint conference
+     */
+    protected void fireActiveSpeakerChanged(long ssrc)
+    {
+        ActiveSpeakerChangedListener[] listeners
+            = getActiveSpeakerChangedListeners();
+
+        for (ActiveSpeakerChangedListener listener : listeners)
+            listener.activeSpeakerChanged(ssrc);
+    }
+
+    /**
+     * Gets the list of listeners to be notified by this detector when the
+     * active speaker changes.
+     *
+     * @return an array of the listeners to be notified by this detector when
+     * the active speaker changes. If no such listeners are registered with this
+     * instance, an empty array is returned. 
+     */
+    protected ActiveSpeakerChangedListener[] getActiveSpeakerChangedListeners()
+    {
+        synchronized (listeners)
+        {
+            return
+                (listeners.size() == 0)
+                    ? NO_LISTENERS
+                    : listeners.toArray(NO_LISTENERS);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public void removeActiveSpeakerChangedListener(
+            ActiveSpeakerChangedListener listener)
+    {
+        if (listener != null)
+        {
+            synchronized (listeners)
+            {
+                listeners.remove(listener);
+            }
+        }
+    }
+}

src/main/java/org/jitsi/utils/dsi/ActiveSpeakerChangedListener.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright @ 2015 Atlassian Pty Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jitsi.utils.dsi;
+
+/**
+ * Implementing classes can be notified about changes to the 'active' stream
+ * (identified by its SSRC) using {@link #activeSpeakerChanged(long)}.
+ *
+ * @author Boris Grozev
+ */
+public interface ActiveSpeakerChangedListener
+{
+    /**
+     * Notifies this listener that the active/dominant stream/speaker has been
+     * changed to one identified by a specific synchronization source
+     * identifier/SSRC.
+     *
+     * @param ssrc the SSRC of the latest/current active/dominant
+     * stream/speaker
+     */
+    public void activeSpeakerChanged(long ssrc);
+}

src/main/java/org/jitsi/utils/dsi/ActiveSpeakerDetector.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright @ 2015 Atlassian Pty Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.jitsi.utils.dsi;
+
+/**
+ * Represents an algorithm for the detection/identification of the
+ * active/dominant speaker/participant/endpoint/stream in a multipoint
+ * conference.
+ * <p>
+ * Implementations of <tt>ActiveSpeakerDetector</tt> get notified about the
+ * (current) audio levels of multiple audio streams (identified by their
+ * synchronization source identifiers/SSRCs) via calls to
+ * {@link #levelChanged(long, int)} and determine/identify which stream is
+ * dominant/active (in terms of speech). When the active stream changes,
+ * listeners registered via
+ * {@link #addActiveSpeakerChangedListener(ActiveSpeakerChangedListener)} are
+ * notified.
+ * </p>
+ *
+ * @author Boris Grozev
+ * @author Lyubomir Marinov
+ */
+public interface ActiveSpeakerDetector
+{
+    /**
+     * Adds a listener to be notified by this active speaker detector when the
+     * active stream changes.
+     *
+     * @param listener the listener to register with this instance for
+     * notifications about changes of the active speaker
+     */
+    public void addActiveSpeakerChangedListener(
+            ActiveSpeakerChangedListener listener);
+
+    /**
+     * Notifies this <tt>ActiveSpeakerDetector</tt> about the latest/current
+     * audio level of a stream/speaker identified by a specific synchronization
+     * source identifier/SSRC.
+     *
+     * @param ssrc the SSRC of the stream/speaker
+     * @param level the latest/current audio level of the stream/speaker with
+     * the specified <tt>ssrc</tt>
+     */
+    public void levelChanged(long ssrc, int level);
+
+    /**
+     * Removes a listener to no longer be notified by this active speaker
+     * detector when the active stream changes.
+     *
+     * @param listener the listener to unregister with this instance for
+     * notifications about changes of the active speaker
+     */
+    public void removeActiveSpeakerChangedListener(
+            ActiveSpeakerChangedListener listener);
+}