P25 Decoder - improved LSM decoding and IMBE audio decoding. Includes redesigned audio output class to handle automatic start/stop of audio playback based on availability of audio data.

2026-11-13 00:57:31 -05:00 · 2015-06-08 01:05:19 +00:00
parent 5dd4454c4c
commit 31482a1014
32 changed files with 366 additions and 432 deletions
--- a/src/audio/inverted/AudioAdapter.java
+++ b/src/audio/inverted/AudioAdapter.java
@@ -0,0 +1,97 @@
+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2014 Dennis Sheirer
+ * 
+ *     This program is free software: you can redistribute it and/or modify
+ *     it under the terms of the GNU General Public License as published by
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program.  If not, see <http://www.gnu.org/licenses/>
+ ******************************************************************************/
+package audio.inverted;
+
+import util.Oscillator;
+import dsp.filter.FilterFactory;
+import dsp.filter.FloatFIRFilter;
+import dsp.filter.Window.WindowType;
+
+/**
+ * Based on the AudioType applied, produces normal, muted, or audio inverted
+ * audio output.
+ */
+public class AudioAdapter
+{
+	private static int mGain = 5;
+	private Oscillator mSineWaveGenerator;
+	private FloatFIRFilter mPostInversionFilter;
+	private FloatFIRFilter mAudioHighPassFilter;
+	private AudioType mAudioType = AudioType.NORMAL;
+	private int mSampleRate;
+	
+	public AudioAdapter( int sampleRate )
+	{
+		mSampleRate = sampleRate;
+		mSineWaveGenerator = new Oscillator( 3000, mSampleRate );
+		mAudioHighPassFilter = new FloatFIRFilter( 
+				FilterFactory.getHighPass( mSampleRate, 200, 1600, 48, 
+						WindowType.HAMMING, true ), mGain );
+		mPostInversionFilter = new FloatFIRFilter( 
+				FilterFactory.getLowPass( mSampleRate, 3000, 5000, 48, 
+						WindowType.HAMMING, true ), mGain );
+	}
+	
+	public void setAudioType( AudioType type )
+	{
+		if( type != null && type != mAudioType )
+		{
+			mAudioType = type;
+
+			int inversionFrequency = type.getAudioInversionFrequency();
+			
+			if( inversionFrequency != 0 )
+			{
+				mSineWaveGenerator.setFrequency( inversionFrequency );;
+			}
+		}
+	}
+	
+    public float get( float sample )
+    {
+    	float retVal;
+    	
+		switch( mAudioType )
+		{
+			case NORMAL:
+				retVal = mAudioHighPassFilter.get( sample );
+				break;
+			case MUTE:
+				retVal = 0.0f;
+				break;
+			case INV2632:
+			case INV2718:
+			case INV2868:
+			case INV3023:
+			case INV3107:
+			case INV3196:
+			case INV3333:
+			case INV3339:
+			case INV3496:
+			case INV3729:
+			case INV4096:
+			default:
+				retVal = (float)( mPostInversionFilter.get( 
+						mAudioHighPassFilter.get( sample ) * 
+						mSineWaveGenerator.nextFloat() ) );
+				break;
+		}
+		
+		return retVal;
+    }
+}