Adds de-emphasis filter to P25 decoded IMBE audio output.

src/audio/output/StereoAudioOutput.java

@@ -95,7 +95,8 @@ public class StereoAudioOutput extends AudioOutput
         catch ( LineUnavailableException e )
 		{
         	mLog.error( "Couldn't obtain source data line for 48kHz PCM stereo "
-        			+ "audio output" );
+        			+ "audio output - mixer [" + mixer.getMixerInfo().getName() + 
+        			"] channel [" + mMixerChannel.name() + "]" );
 		}
 	}
 

src/buffer/FloatCircularBuffer.java

@@ -40,6 +40,11 @@ public class FloatCircularBuffer
 		Arrays.fill( mBuffer, (float)0.0 );
 	}
 	
+	public int getSize()
+	{
+		return mBuffer.length;
+	}
+	
 	public float[] getBuffer()
 	{
 		return mBuffer;

src/dsp/filter/iir/DeemphasisFilter.java

@@ -0,0 +1,60 @@
+package dsp.filter.iir;
+
+import sample.real.RealBuffer;
+
+public class DeemphasisFilter
+{
+	private static final float MAX_SAMPLE_VALUE = 0.95f;
+	private float mAlpha;
+	private float mGain;
+	private float mPrevious = 0.0f;
+	
+	public DeemphasisFilter( float sampleRate, float cutoff, float gain )
+	{
+		mAlpha = (float)Math.exp( -2.0 * Math.PI * cutoff * ( 1.0 / sampleRate ) );
+		mGain = gain;
+	}
+	
+	public float filter( float sample )
+	{
+		mPrevious = sample + ( mAlpha * mPrevious );
+		
+		return declip( mPrevious * mGain );
+	}
+	
+	private float declip( float value )
+	{
+		if( value > MAX_SAMPLE_VALUE )
+		{
+			return MAX_SAMPLE_VALUE;
+		}
+		else if( value < -MAX_SAMPLE_VALUE )
+		{
+			return -MAX_SAMPLE_VALUE;
+		}
+		
+		else return value;
+	}
+	
+	public float[] filter( float[] samples )
+	{
+		for( int x = 0; x < samples.length; x++ )
+		{
+			samples[ x ] = filter( samples[ x ] );
+		}
+		
+		return samples;
+	}
+	
+	public RealBuffer filter( RealBuffer buffer )
+	{
+		float[] samples = buffer.getSamples();
+		
+		for( int x = 0; x < samples.length; x++ )
+		{
+			samples[ x ] = filter( samples[ x ] );
+		}
+
+		return buffer;
+	}
+}

src/module/decode/p25/P25DecoderPanel.java

@@ -149,7 +149,7 @@ public class P25DecoderPanel extends DecoderPanel
 						{
 							mFromAlias.setText( from.getName() );
 							
-							String icon = from.getIconName();
+							final String icon = from.getIconName();
 							
 							if( icon != null )
 							{
@@ -180,7 +180,7 @@ public class P25DecoderPanel extends DecoderPanel
 						{
 							mToAlias.setText( to.getName() );
 
-							String icon = to.getIconName();
+							final String icon = to.getIconName();
 							
 							if( icon != null )
 							{

src/module/decode/p25/audio/P25AudioModule.java

@@ -6,8 +6,6 @@ import message.IMessageListener;
 import message.Message;
 import module.Module;
 import module.decode.p25.message.ldu.LDUMessage;
-import module.decode.p25.message.tdu.TDUMessage;
-import module.decode.p25.message.tdu.lc.TDULinkControlMessage;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -23,6 +21,8 @@ import audio.squelch.ISquelchStateListener;
 import audio.squelch.SquelchState;
 import controller.channel.ChannelEvent;
 import controller.channel.IChannelEventListener;
+import dsp.audio.P25AGC;
+import dsp.filter.iir.DeemphasisFilter;
 
 public class P25AudioModule extends Module implements Listener<Message>, 
 	IAudioPacketProvider, IMessageListener, IChannelEventListener, 
@@ -43,6 +43,8 @@ public class P25AudioModule extends Module implements Listener<Message>,
 	private AudioMetadata mAudioMetadata;
 	private ChannelEventListener mChannelEventListener = new ChannelEventListener();
 	private SquelchStateListener mSquelchStateListener = new SquelchStateListener();
+//	private P25AGC mAGC = new P25AGC( 2.0, 10.0 );
+	private DeemphasisFilter mDeemphasis = new DeemphasisFilter( 48000.0f, 300.0f, 0.6f );
 
 	public P25AudioModule( boolean record )
 	{
@@ -89,9 +91,10 @@ public class P25AudioModule extends Module implements Listener<Message>,
 	}
 
 	/**
-	 * Primary inject point for p25 imbe audio frame messages.  Each LDU audio 
-	 * message contains 9 imbe voice frames.  If the audio is not encrypted,
-	 * we insert each audio frame asynchronously into the audio converter.
+	 * Primary processing method for p25 imbe audio frame messages.  Each LDU 
+	 * audio message contains 9 imbe voice frames.  Each frame is converted to
+	 * audio when the JMBE library is loaded, processed by auto-gain, and 
+	 * broadcast to the audio packet listener.
 	 */
 	public void receive( Message message )
 	{
@@ -101,15 +104,15 @@ public class P25AudioModule extends Module implements Listener<Message>,
 			{
 				LDUMessage ldu = (LDUMessage)message;
 				
-				/* If we detect a valid LDU message with the encryption flag
-				 * set to true, we toggle the encrypted audio state until we 
-				 * receive the first TDU or TDULC message, then reset it. */
+				/* Only process unencrypted audio frames */
 				if( !( ldu.isValid() && ldu.isEncrypted() ) )
 				{
-					for( byte[] frame: ((LDUMessage)message).getIMBEFrames() )
+					for( byte[] frame: ldu.getIMBEFrames() )
 					{
 						float[] audio = mAudioConverter.decode( frame );
 
+						audio = mDeemphasis.filter( audio );
+
 						mAudioPacketListener.receive( 
 								new AudioPacket( audio, mAudioMetadata.copyOf() ) );
 					}

src/source/wave/RealWaveSource.java

@@ -36,7 +36,8 @@ import source.IControllableFileSource;
 import source.IFrameLocationListener;
 import source.RealSource;
 
-public class RealWaveSource extends RealSource implements IControllableFileSource
+public class RealWaveSource extends RealSource 
+	implements IControllableFileSource, AutoCloseable
 {
 	private final static Logger mLog = 
 			LoggerFactory.getLogger( RealWaveSource.class );
@@ -168,6 +169,11 @@ public class RealWaveSource extends RealSource implements IControllableFileSourc
         	{
             	if( samplesRead < buffer.length )
             	{
+            		if( samplesRead == -1 )
+            		{
+            			throw new IOException( "End of recording" );
+            		}
+            		
             		buffer = Arrays.copyOf( buffer, samplesRead );
             	}