Resolves issue #23.

Adds audio output display and management options supporting mono and 
stereo output options.

Provides audio output supporting prioritization by talkgroup and/or 
channel selection.

Supports muting all channels, or muting individual channels and
individual audio gain/volume controls.

src/audio/output/MonoAudioOutput.java

@@ -6,20 +6,19 @@ import java.nio.ShortBuffer;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Executors;
-import java.util.concurrent.LinkedTransferQueue;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import javax.sound.sampled.AudioSystem;
 import javax.sound.sampled.BooleanControl;
 import javax.sound.sampled.FloatControl;
 import javax.sound.sampled.LineUnavailableException;
+import javax.sound.sampled.Mixer;
 import javax.sound.sampled.SourceDataLine;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import source.mixer.MixerChannel;
 import audio.AudioEvent;
 import audio.AudioFormats;
 import audio.AudioPacket;
@@ -27,14 +26,14 @@ import audio.AudioPacket.Type;
 import controller.NamingThreadFactory;
 
 /**
- * Audio output with automatic flow control based on the availability of 
+ * Mono Audio output with automatic flow control based on the availability of 
  * audio data packets.  
  */
 public class MonoAudioOutput extends AudioOutput
 {
 	private final static Logger mLog = LoggerFactory.getLogger( MonoAudioOutput.class );
 
-	/* Output line buffer size is set at one second of audio at 48 kHz and
+	/* Output line buffer size is set at one half second of audio at 48 kHz and
 	 * two bytes per sample */
 	private final static int BUFFER_SIZE = 48000;
 	
@@ -42,40 +41,34 @@ public class MonoAudioOutput extends AudioOutput
 	 * audio and automatically starting or stopping audio playback.  We set the 
 	 * data line available space threshold to start when we're 20 ms away from 
 	 * being full, and the stop threshold when 20 ms away from being empty */
-	private final static int SAMPLE_SIZE_40_MS = 48000 / 25;
+	private final static int SAMPLE_SIZE_40_MS = BUFFER_SIZE / 25;
 	private final static int START_THRESHOLD = SAMPLE_SIZE_40_MS;
 	private final static int STOP_THRESHOLD = BUFFER_SIZE - SAMPLE_SIZE_40_MS;
-	
-	private LinkedTransferQueue<AudioPacket> mBuffer = new LinkedTransferQueue<>();
 
-	private ScheduledExecutorService mExecutorService;
-	
 	private SourceDataLine mOutput;
 	private FloatControl mGainControl;
 	private BooleanControl mMuteControl;
 	
-	private boolean mCanProcessAudio;
-	
-	private long mLastBufferReceived;
-	
 	private AudioEvent mAudioStartEvent;
 	private AudioEvent mAudioStopEvent;
 	
-	public MonoAudioOutput()
+	public MonoAudioOutput( Mixer mixer )
 	{
 		super();
-		
-		mAudioStartEvent = new AudioEvent( AudioEvent.Type.AUDIO_STARTED, getChannelName() );
-		mAudioStopEvent = new AudioEvent( AudioEvent.Type.AUDIO_STOPPED, getChannelName() );
+
+		mAudioStartEvent = new AudioEvent( AudioEvent.Type.AUDIO_STARTED, 
+				getChannelName() );
+		mAudioStopEvent = new AudioEvent( AudioEvent.Type.AUDIO_STOPPED, 
+				getChannelName() );
 
 		try
 		{
-			mOutput = AudioSystem.getSourceDataLine( 
-						AudioFormats.PCM_SIGNED_48KHZ_16BITS );
-
+			mOutput = (SourceDataLine)mixer.getLine( 
+					AudioFormats.MONO_SOURCE_DATALINE_INFO );
+			
 			if( mOutput != null )
 			{
-				mOutput.open( AudioFormats.PCM_SIGNED_48KHZ_16BITS, BUFFER_SIZE );
+				mOutput.open( AudioFormats.PCM_SIGNED_48KHZ_16BITS_MONO, BUFFER_SIZE );
 				
 				mCanProcessAudio = true;
 				
@@ -103,47 +96,18 @@ public class MonoAudioOutput extends AudioOutput
 	@Override
 	public String getChannelName()
 	{
-		return "Mono";
-	}
-
-	/**
-	 * Timestamp when most recent buffer was received
-	 */
-	public long getLastBufferReceived()
-	{
-		return mLastBufferReceived;
+		return MixerChannel.MONO.getLabel();
 	}
 
 	public void dispose()
 	{
 		super.dispose();
 		
-		mCanProcessAudio = false;
-
-		mBuffer.clear();
-		
-		if( mExecutorService != null )
-		{
-			mExecutorService.shutdown();
-		}
-		
 		if( mOutput != null )
 		{
 			mOutput.close();
 		}
 	}
-
-	@Override
-	public void receive( AudioPacket packet )
-	{
-		if( mCanProcessAudio )
-		{
-			mLastBufferReceived = System.currentTimeMillis();
-			
-			mBuffer.add( packet );
-		}
-	}
-	
 	
 	public class QueueProcessor implements Runnable
 	{
@@ -233,17 +197,27 @@ public class MonoAudioOutput extends AudioOutput
 		}
 	}
 
+	@Override
+	public void setMuted( boolean muted )
+	{
+		if( mMuteControl != null )
+		{
+			mMuteControl.setValue( muted );
+			
+			broadcast( new AudioEvent( muted ? AudioEvent.Type.AUDIO_MUTED : 
+				AudioEvent.Type.AUDIO_UNMUTED, getChannelName() ) );
+		}
+	}
 
 	@Override
-	public BooleanControl getMuteControl()
+	public boolean isMuted()
 	{
-		return mMuteControl;
-	}
-	
-	@Override
-	public boolean hasMuteControl()
-	{
-		return mMuteControl != null;
+		if( mMuteControl != null )
+		{
+			return mMuteControl.getValue();
+		}
+		
+		return false;
 	}
 
 	@Override