mirror of
https://github.com/DSheirer/sdrtrunk.git
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87 lines
2.8 KiB
Java
87 lines
2.8 KiB
Java
/*******************************************************************************
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* SDR Trunk
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* Copyright (C) 2014 Dennis Sheirer
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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******************************************************************************/
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package io.github.dsheirer.audio.invert;
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import io.github.dsheirer.audio.InversionFrequency;
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import io.github.dsheirer.dsp.filter.Filters;
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import io.github.dsheirer.dsp.filter.FloatFIRFilter;
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import io.github.dsheirer.dsp.mixer.IOscillator;
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import io.github.dsheirer.dsp.mixer.Oscillator;
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import io.github.dsheirer.sample.real.RealSampleListener;
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/**
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* Applies audio inversion (or un-inversion) to a broadcast of float audio samples
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* by multiplying each successive sample by either a 1 or a -1 value.
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*/
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public class AudioInverter implements RealSampleListener
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{
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private IOscillator mSineWaveGenerator;
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private FloatFIRFilter mPostInversionLowPassFilter;
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private RealSampleListener mListener;
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public AudioInverter( int inversionFrequency, int sampleRate )
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{
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mSineWaveGenerator = new Oscillator( inversionFrequency, sampleRate );
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mPostInversionLowPassFilter = new FloatFIRFilter(
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Filters.FIRLP_55TAP_48000FS_3000FC.getCoefficients(), 1.04f );
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mPostInversionLowPassFilter.setListener( new FilteredSampleProcessor() );
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}
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public AudioInverter( InversionFrequency frequency, int sampleRate )
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{
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this( frequency.getFrequency(), sampleRate );
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}
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public void setListener( RealSampleListener listener )
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{
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mListener = listener;
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}
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@Override
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public void receive( float sample )
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{
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//Multiply the sample by the folding frequency and then send it to
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//the low pass filter
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if( mPostInversionLowPassFilter != null )
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{
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mPostInversionLowPassFilter.receive(
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sample * mSineWaveGenerator.inphase() );
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mSineWaveGenerator.rotate();
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}
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}
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/**
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* Simple class to receive the output of the FIR low pass filter and then
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* send it to the registered listener(s)
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*/
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class FilteredSampleProcessor implements RealSampleListener
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{
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@Override
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public void receive( float sample )
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{
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if( mListener != null )
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{
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mListener.receive( sample );
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}
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}
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}
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}
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