sdrtrunk/src/main/java/io/github/dsheirer/audio/AudioUtils.java

/*******************************************************************************
 * sdr-trunk
 * Copyright (C) 2014-2018 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 io.github.dsheirer.audio;

import io.github.dsheirer.sample.ConversionUtils;
import io.github.dsheirer.sample.buffer.ReusableAudioPacket;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.List;

public class AudioUtils
{
    private final static Logger mLog = LoggerFactory.getLogger(AudioUtils.class);

    /**
     * Converts the audio packets into a byte array of 16-bit, little-endian audio samples
     */
    public static byte[] convertTo16BitSamples(List<ReusableAudioPacket> audioPackets)
    {
        ByteArrayOutputStream stream = new ByteArrayOutputStream();

        try
        {
            for(ReusableAudioPacket audioPacket: audioPackets)
            {
                //Converting from 32-bit floats to signed 16-bit samples
                ByteBuffer buffer = ConversionUtils.convertToSigned16BitSamples(audioPacket.getAudioSamples());
                stream.write(buffer.array());
                audioPacket.decrementUserCount();
            }
        }
        catch(IOException e)
        {
            mLog.error("Error writing converted PCM bytes to output stream");
        }

        return stream.toByteArray();
    }
}