LongEcho.java

package com.jsyn.examples;

import java.io.File;
import java.io.IOException;

import com.jsyn.JSyn;
import com.jsyn.Synthesizer;
import com.jsyn.data.FloatSample;
import com.jsyn.devices.AudioDeviceManager;
import com.jsyn.unitgen.ChannelIn;
import com.jsyn.unitgen.ChannelOut;
import com.jsyn.unitgen.FixedRateMonoReader;
import com.jsyn.unitgen.FixedRateMonoWriter;
import com.jsyn.unitgen.Maximum;
import com.jsyn.unitgen.Minimum;
import com.jsyn.util.WaveFileWriter;

/**
 * Record audio then play back.
 * @author  Phil Burk (C) 2010 Mobileer Inc
 *
 */
public class LongEcho
{
	final static int DELAY_SECONDS = 4;
	Synthesizer synth;
	ChannelIn channelIn;
	ChannelOut channelOut;
	FloatSample sample;
	FixedRateMonoReader reader;
	FixedRateMonoWriter writer;
	Minimum minner;
	Maximum maxxer;

	private void test() throws IOException
	{
		// Create a context for the synthesizer.
		synth = JSyn.createSynthesizer();
		// Add a tone generator.
		synth.add( channelIn = new ChannelIn() );
		// Add an output mixer.
		synth.add( channelOut = new ChannelOut() );

		synth.add( minner = new Minimum() );
		synth.add( maxxer = new Maximum() );
		synth.add( reader = new FixedRateMonoReader() );
		synth.add( writer = new FixedRateMonoWriter() );
		
		sample = new FloatSample( 44100 * DELAY_SECONDS, 1 );

		maxxer.inputB.set( -0.98 ); // clip
		minner.inputB.set(  0.98 );
		
		// Connect the input to the output.
		channelIn.output.connect( minner.inputA );
		minner.output.connect( maxxer.inputA );
		maxxer.output.connect( writer.input );
		
		reader.output.connect( channelOut.input );
		
		// Both stereo.
		int numInputChannels = 2;
		int numOutputChannels = 2;
		synth.start( 44100, AudioDeviceManager.USE_DEFAULT_DEVICE, numInputChannels, AudioDeviceManager.USE_DEFAULT_DEVICE,
				numOutputChannels );

		writer.start();
		channelOut.start();

		// For a long echo, read cursor should be just in front of the write cursor.
		reader.dataQueue.queue( sample, 1000, sample.getNumFrames() - 1000 );
		// Loop both forever.
		reader.dataQueue.queueLoop( sample, 0, sample.getNumFrames() );
		writer.dataQueue.queueLoop( sample, 0, sample.getNumFrames() );
		System.out.println("Start talking. You should hear an echo after " + DELAY_SECONDS + " seconds.");
		// Sleep a while.
		try
		{
			double time = synth.getCurrentTime();
			// Sleep for a while
			synth.sleepUntil( time + 30.0 );
		} catch( InterruptedException e )
		{
			e.printStackTrace();
		}
		
		saveEcho( new File("saved_echo.wav"));
		// Stop everything.
		synth.stop();
	}

	private void saveEcho(  File file ) throws IOException
	{
		WaveFileWriter writer = new WaveFileWriter( file );
		writer.setFrameRate( 44100 );
		writer.setSamplesPerFrame( 1 );
		writer.setBitsPerSample( 16 );
		float[] buffer = new float[sample.getNumFrames()];
		sample.read(buffer);
		for( float v : buffer )
		{
			writer.write(  (double) v );
		}
		writer.close();
	}

	public static void main( String[] args )
	{
		try
		{
			new LongEcho().test();
		} catch( IOException e )
		{
			e.printStackTrace();
		}
	}
}