/*******************************************************************************
* sdrtrunk
* Copyright (C) 2014-2016 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.convert;
import audio.AudioFormats;
import audio.AudioPacket;
import audio.AudioUtils;
import net.sourceforge.lame.lowlevel.LameEncoder;
import net.sourceforge.lame.mp3.Lame;
import net.sourceforge.lame.mp3.MPEGMode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.ByteArrayOutputStream;
import java.util.Arrays;
import java.util.List;
public class MP3AudioConverter implements IAudioConverter
{
private final static Logger mLog = LoggerFactory.getLogger( MP3AudioConverter.class );
public static final int AUDIO_QUALITY = Lame.QUALITY_LOW;
private LameEncoder mEncoder;
private ByteArrayOutputStream mMP3Stream = new ByteArrayOutputStream();
private byte[] mMP3Buffer;
/**
* Converts PCM 8kHz 16-bit Little Endian audio packets to Mono, Low Quality MP3 compressed audio.
*
* @param bitRate for converted MP3 audio
* @param variableBitRate (VBR) true or false for constant bit rate (CBR)
*/
public MP3AudioConverter(int bitRate, boolean variableBitRate)
{
mEncoder = new LameEncoder(AudioFormats.PCM_SIGNED_8KHZ_16BITS_MONO,
bitRate, MPEGMode.MONO, AUDIO_QUALITY, variableBitRate);
mMP3Buffer = new byte[mEncoder.getPCMBufferSize()];
}
@Override
public byte[] convert(List<AudioPacket> audioPackets)
{
mMP3Stream.reset();
byte[] pcmBytes = AudioUtils.convertTo16BitSamples(audioPackets);
int pcmBufferSize = Math.min(mMP3Buffer.length, pcmBytes.length);
int mp3BufferSize = 0;
int pcmBytesPosition = 0;
try
{
while (0 < (mp3BufferSize = mEncoder.encodeBuffer(pcmBytes, pcmBytesPosition, pcmBufferSize, mMP3Buffer)))
{
pcmBytesPosition += pcmBufferSize;
pcmBufferSize = Math.min(mMP3Buffer.length, pcmBytes.length - pcmBytesPosition);
mMP3Stream.write(mMP3Buffer, 0, mp3BufferSize);
}
return mMP3Stream.toByteArray();
}
catch(Exception e)
{
mLog.error("There was an error converting audio to MP3: " + e.getMessage());
return new byte[0];
}
}
@Override
public byte[] flush()
{
byte[] lastPartialFrame = new byte[mEncoder.getMP3BufferSize()];
int length = mEncoder.encodeFinish(lastPartialFrame);
return Arrays.copyOf(lastPartialFrame, length);
}
}