Audio outputs - added exception handler to catch any errors that occur

while the buffer processor thread is running.

Added check for 0 space available in data line buffers to avoid trying
to write a zero-length audio chunk to the data line.

Added thread sleep for 100 milliseconds when we detect that the data
line buffer is full, to allow time for the data line to drain before we
check it again.  Hopefully this should minimize the chattering during
playback when the code was repeatedly hitting the available() method to
check for space availability.

src/audio/output/MonoAudioOutput.java

@@ -24,7 +24,6 @@ import audio.AudioEvent;
 import audio.AudioFormats;
 import audio.AudioPacket;
 import audio.AudioPacket.Type;
-import audio.output.StereoAudioOutput.QueueProcessor;
 import controller.NamingThreadFactory;
 
 /**
@@ -144,12 +143,10 @@ public class MonoAudioOutput extends AudioOutput
 	{
 		private AtomicBoolean mProcessing = new AtomicBoolean();
 		
-		public QueueProcessor()
-		{
-		}
-
 		@Override
 		public void run()
+		{
+			try
 			{
 				/* The mProcessing flag ensures that only one instance of the
 				 * processor can run at any given time */
@@ -206,16 +203,32 @@ public class MonoAudioOutput extends AudioOutput
 
 											if( available < toWrite )
 											{
-											wrote += mOutput.write( buffer.array(), wrote, 
+												if( available > 0 )
-													available );
+												{
+													wrote += mOutput.write( buffer.array(), 
+														wrote, available );
+
+													checkStart();
+												}
+												else
+												{
+													try
+													{
+														Thread.sleep( 100 );
+													} 
+													catch ( InterruptedException e )
+													{
+														mLog.debug( "Mono Audio Output - interrupted while sleeping awaiting buffer drain" );
+													}
+												}
 											}
 											else
 											{
 												wrote += mOutput.write( buffer.array(), wrote, 
 														toWrite );
-										}
 												
 												checkStart();
+											}
 											
 											toWrite = buffer.array().length - wrote;
 										}
@@ -236,6 +249,11 @@ public class MonoAudioOutput extends AudioOutput
 					mProcessing.set( false );
 				}
 			}
+			catch( Exception e )
+			{
+				mLog.error( "Error while processing audio buffers", e );
+			}
+		}
 		
 		private void checkStart()
 		{

src/audio/output/StereoAudioOutput.java

@@ -176,6 +176,8 @@ public class StereoAudioOutput extends AudioOutput
 
 		@Override
 		public void run()
+		{
+			try
 			{
 				/* The mProcessing flag ensures that only one instance of the
 				 * processor can run at any given time */
@@ -221,16 +223,21 @@ public class StereoAudioOutput extends AudioOutput
 
 											if( available < toWrite )
 											{
-											wrote += mOutput.write( buffer.array(), wrote, 
+												if( available > 0 )
-													available );
+												{
+													wrote += mOutput.write( buffer.array(), 
+															wrote, available );
+
+													checkStart();
+												}
 											}
 											else
 											{
 												wrote += mOutput.write( buffer.array(), wrote, 
 														toWrite );
-										}
 
 												checkStart();
+											}
 
 											toWrite = buffer.array().length - wrote;
 										}
@@ -251,6 +258,11 @@ public class StereoAudioOutput extends AudioOutput
 					mProcessing.set( false );
 				}
 			}
+			catch( Exception e )
+			{
+				mLog.error( "Error while processing audio buffers", e );
+			}
+		}
 		
 		private void checkStart()
 		{